8803 500 004 Bus Priority Measures

8803-500-004 Rev.1.00 January 2004 UNDER REVIEW

Design and Planning Guidelines for Public Transport Infrastructure

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Design & Planning Guidelines For Public Transport Infrastructure Bus Priority Measures: Principles and Design PAGE 2 8803-500-004 Rev1.00

Document Issue Approval Name Position Signature Date Prepared by P Johnstone Principal Transport Planner

ARRB Transport Research Ltd 22 Jan 2004

Reviewed by S Brennan Project Manager Public Transport Authority

Approved by M Somerville-Brown Infrastructure Procurement Manager Public Transport Authority

Document Amendment Record Date Revision Amendment comment Affected pages

22 January 2004 1.00 First Issue All

PROJECT ABSTRACT: This document – Bus Priority Measures: Principles & Design – is a best-practice guide for transport planners and town planners, engineers, bus service providers, and others who may be planning and/or providing bus public transport infrastructure and services.

The guide is one of four companion volumes in the series – Design and Planning Guidelines for Public Transport Infrastructure. Three other guides address: - Bus Route Planning & Transit Streets - Traffic Management & Control Devices - Maintenance & Constructability

Bus Priority Measures: Principles & Design is presented in five broad sections: - The Challenge of Providing Priority for Public Transport - Regional-Level Priority - Local-Level Priority - Planning and Justifying Bus Priority - Intelligent Transport Systems (ITS) for Bus Priority The guide also includes a bibliography, several technical appendices and a glossary of terms to assist users of the guide.

This guide is intended to provide examples of best-practice interventions that can provide on-road public transport with priority treatment relative to general traffic, thereby achieving strategic transport systems benefits and/or operational benefits for public transport.

ACKNOWLEDGMENTS This guideline has been prepared in close consultation with representatives from: - Department for Planning and Infrastructure (DPI) - Public Transport Authority (Transperth Group) - Main Roads Western Australia (MRWA) The authors also acknowledge that a number of illustrations of typical on-road public transport facilities have been drawn from the report by PPK and McCormick Rankin Cagney entitled: “Brisbane High Occupancy Vehicle Arterial Roads Study” Final Report for Queensland Main Roads, Queensland Transport and Brisbane City Council, January 2001.


Contents Technical Glossary ......................................................................................................................... 5 1. The Challenge ............................................................................................................................. 6

1.1 Government Transport & Public Transport Policy ................................................................. 6 1.2 Priority for Public Transport .................................................................................................. 6 1.3 Buses & Traffic Congestion ................................................................................................... 6 1.4 An Underlying Premise .......................................................................................................... 7 1.5 Comprehensive & Localised Interventions ............................................................................ 7

1.5.1 Auckland – “Buses First” .............................................................................................................. 8 1.6 Defining “Priority” ................................................................................................................. 9 1.7 Examples of Bus Priority Infrastructure ................................................................................. 9

2. Regional-Level Priority ............................................................................................................ 11 2.1 Transit Malls ......................................................................................................................... 11 2.2 Bus Transitways (Busways) ................................................................................................. 11

2.2.1 Exclusive Bus Transitways .......................................................................................................... 11 2.2.2 Guided Busways .......................................................................................................................... 15 2.2.3 Semi-Exclusive Transitways ........................................................................................................ 16 2.2.4 Non-Exclusive Bus Transitways .................................................................................................. 16

2.3 Bus Lanes ............................................................................................................................. 16 2.3.1 Bus Lane; Concurrent-Flow; Kerb-Side ..................................................................................... 18 2.3.2 Permitted Turns Across Kerb-Side Bus Lane .............................................................................. 19 2.3.3 Bus Lane; Concurrent-Flow; Central Lane................................................................................. 19 2.3.4 Bus Lane; Concurrent-Flow; Median ......................................................................................... 20 2.3.5 Concurrent-Flow Bus Lane Set-Back .......................................................................................... 22 2.3.6 Bus Lane; Contra-Flow ............................................................................................................... 23 2.3.7 Short Bus Lanes at Traffic Signals .............................................................................................. 24 2.3.8 Enforcement of Bus Lanes ........................................................................................................... 25

2.4 Freeway Access Ramps ........................................................................................................ 27 2.5 Transit Lanes ........................................................................................................................ 28

3. Local-Level Priority ................................................................................................................. 29 3.1 Bus Nibs ............................................................................................................................... 29 3.2 Bus Stop Run-Ins and Run-Outs .......................................................................................... 30 3.3 Bus Advance Areas & Pre-Signals ...................................................................................... 30 3.4 Queue Re-Location Bus Lanes and Pre-Signals ................................................................... 32 3.5 Queue-Jump Lanes ............................................................................................................... 32 3.6 Bus-Only Streets ................................................................................................................... 33 3.7 Other Bus-Only Connector Links & Bus Gates ................................................................... 35 3.8 “No -Turning” Exemptions for Buses .................................................................................. 37 3.9 Bus Acceleration Lanes ........................................................................................................ 38 3.10 Supportive Interventions .................................................................................................... 38

3.10.1 No-Stopping Restrictions on Priority Bus Routes ...................................................................... 38 3.10.2 Bus Stop Clearways ................................................................................................................... 38 3.10.3 Priority Route Enforcement, Parking & Infringement Fines ..................................................... 39 3.10.4 Bus Stop Re-Location ................................................................................................................ 39 3.10.5 Reduction in Bus Stopping Time ................................................................................................ 39

4. Planning & Justifying Bus Priority Infrastructure ............................................................... 40 4.1 A Project Prioritisation & Evaluation Model (PPEM) ......................................................... 40 4.2 Objectives & Performance Measures for Bus Priority ......................................................... 41 4.3 Conclusions for the Assessment of Bus Priority Interventions ............................................ 41


5. Intelligent Transport Systems (ITS) for Bus Priority ........................................................... 42

5.1 Passive Signal Priority .......................................................................................................... 42 5.1.1 Reduced Cycle Time .................................................................................................................... 42 5.1.2 Priority Movement Repetition in Cycle ....................................................................................... 42 5.1.3 Green Priority Weighting ............................................................................................................ 43 5.1.4 Phasing Design ............................................................................................................................ 43 5.1.5 Signal Linking for Bus Progression ............................................................................................. 43 5.1.6 Diurnal Phasing Variation .......................................................................................................... 43 5.1.7 Synopsis ....................................................................................................................................... 43

5.2 Active Signal Priority ........................................................................................................... 43 5.2.1 Green Extension .......................................................................................................................... 43 5.2.2 Green Early Start ........................................................................................................................ 43 5.2.3 Special Phase............................................................................................................................... 43 5.2.4 Phase Suppression ....................................................................................................................... 44 5.2.5 Priority Phase Sequences ............................................................................................................ 44 5.2.6 Phase Compensation ................................................................................................................... 44 5.2.7 Flexible Window Stretching ......................................................................................................... 44 5.2.8 Priority Green and B-Lights ........................................................................................................ 44

5.3 Issues in Evaluating Active Priority ..................................................................................... 46 5.4 Generic Techniques to Assign Priority ................................................................................. 46

5.4.1 Selective Vehicle Detection (SVD) ............................................................................................... 46 5.4.2 Automatic Vehicle Location (AVL) .............................................................................................. 48

5.5 Australasian Intelligent Transport Systems (ITS) Bus Priority Examples ........................... 49 5.5.1 SCATS Operations in WA ............................................................................................................ 49 5.5.2 SCATS Operations for Melbourne Tram Priority ........................................................................ 49 5.5.3 Public Transport Information & Priority System (PTIPS), Sydney ............................................. 50 5.5.4 BLISS / RAPID – Brisbane .......................................................................................................... 51

5.6 International ITS Bus Priority Applications ......................................................................... 53 6. Bibliography .............................................................................................................................. 55 Appendix 1: PPEM Framework .................................................................................................. 57 Appendix 2: Case Studies of Approaches to Justifying Bus Priority ....................................... 58

Case Study 1: Potential HOV & Bus Priority Framework (DPI, 1996) ..................................... 58 Case Study 2: Synopsis of Research into Warrants for Bus Lanes ............................................ 59 Case Study 3: Other Bus Warrants & Decision Frameworks ..................................................... 59 Case Study 4: Justifying Bus Priority in Oregon, USA .............................................................. 60 Case Study 5: Gold Coast Hwy. Assessment of Bus Priority..................................................... 61

Appendix 3: Public Transport Information & Priority System (PTIPS) ................................ 62 Appendix 4: Schematic of PTIPS Architecture ......................................................................... 64 Appendix 5: RAPID Bus Priority System Architecture ............................................................ 65 Appendix 6: International ITS & Bus Priority Examples ........................................................ 66 Appendix 7: Recent Public Transport Priority Projects in Perth ............................................ 71


Technical Glossary

AVI Automatic Vehicle Identification

AVL Automatic Vehicle Location

BLISS Brisbane Linked Intersection Signal System

GLONASS Global Navigation Satellite System

GPS Global Positioning System

GSM Global System for Mobile telecommunications

GUI Graphical User Interface

IP Internet Protocol

ITS Intelligent Transport System

LAN Local Area Network

LRT Light Rail Transit

MTS Metropolitan Transport Strategy (Perth, 1995)

PTIPS Public Transport Information and Priority System

RAPID Real-time Advanced Priority and Information Delivery

RTA Roads and Traffic Authority of NSW

SCATS Sydney Coordinated Adaptive Traffic System

SVD Selective Vehicle Detection

TCP Transmission Control Protocol

VID Vehicle Identification

VTS Vehicle Tracking System

UTC Urban Traffic Control system

RTPI/SPS Real Time Passenger Information / Signal Pre-emption System

TRAFFIC CONTROLLER TERMS

Call When a phase is “called”, it will be the next active phase for a set of traffic signals at an intersection.

Cycle The set of phases at a set of traffic signals controlling an intersection.

Phase A part of the cycle for a set of traffic signals at an intersection that provides flow for one set of directions at the intersection.

Priority A controlled change to the normal duration for phases for a set of traffic signals at an intersection. The change is designed to allow a vehicle requiring priority to pass through the intersection unimpeded. Also known as signal pre-emption.

Stretch Phase The primary phase to which any free time is given in the cycle for a set of traffic signals at an intersection. The stretch phase is “stretched” when other phases for which there is no demand are not run. The stretch phase is also the phase during which SCATS achieves coordination between sets of traffic signals.

SCATS ITS Port The component of the SCATS system that allows external (non-SCATS) applications to communicate with SCATS. Thus external applications make requests of SCATS and receive replies from SCATS via the SCATS ITS Port.

Design & Planning Guidelines For Public Transport InfrastructureBus Priority Measures: Principles and Design PAGE 6 8803-500-004 Rev1.00

1. The Challenge 1.1 Government Transport & Public Transport Policy The Metropolitan Transport Strategy (MTS) adopted in 1995, seeks to establish a better balanced and more sustainable metropolitan transport system for Perth. To achieve the MTS objectives, the strategy establishes targets for improving the mode split for public transport, walking and cycling, including doubling the public transport share of all trips from 6% to 12% by 2029.

Better Public Transport: Ten-Year Plan for Transperth 1998-2007, was adopted as the implementation strategy for the Department for Planning & Infrastructure’s charter to achieve the MTS strategic targets.

The Ten-Year Plan guides short- and medium-term planning of the Transperth service network and will see increased public transport service frequencies and more emphasis on local bus services connecting with the rail system.

However, to achieve the ambitious MTS transport system targets, public transport services will need to be made increasingly attractive to a range of existing and potential users. By offering a high quality of safe and reliable service, the public transport sector may achieve its mode-share targets for a significantly expanded proportion of overall metropolitan trip-making.

One of the key means of achieving the necessary high level of customer service will be through the provision of priority to public transport services, especially where they compete in congested conditions with other forms of transport.

1.2 Priority for Public Transport In urban areas, bus travel times can typically be double those of corresponding motor vehicle travel times. To make bus travel times “competitive” with motor vehicle travel times, a range of priority interventions have been selectively applied to bus services over a period of at least 30 years.

One of the basic challenges in urban transport is to ensure a sustainable balance between public and private modes of travel. To achieve this, there is a strong argument that public transport should be favoured over private transport as much as possible, particularly in major urban corridors.

There are two general categories of measures that can be used to achieve the desired inter-modal balance between public transport and automobiles: public transport incentives and automobile disincentives.

The focus in this Guideline Module is on public transport incentives, or priorities, with specific reference to the bus mode. However, automobile disincentives, such as limiting parking capacity, increasing parking charges, introducing road pricing, discontinuing the “subsidy” of car travel, enhanced land use planning, and other initiatives, should form complimentary components of a genuinely comprehensive and integrated approach to sustainable transport systems planning.

1.3 Buses & Traffic Congestion The level of general traffic congestion that impedes the efficient flow of buses determines the potential benefit of bus service facilitation and/or priority measures. Where congestion is high, bus journeys not only take significantly longer than might otherwise be the case. More significantly for passengers, and potential passengers, schedule reliability is adversely affected and the degree of confidence with which passengers can depend upon a timely bus system is eroded.

Indeed, the elasticity of demand for bus services tends to be greater for time and schedule reliability than for price, or bus fare level.

To redress bus travel time problems resulting from ambient traffic congestion, numerous cities have developed plans to facilitate bus services and/or for the provision of active priority for bus services.


1.4 An Underlying Premise It is possible to provide bus services with a significant level of priority without imposing serious delays on other traffic. The capacity of the road network for general traffic is, to a large extent, maintained by ensuring that bus priority measures do not affect capacity at key intersections. In many situations, the introduction of bus priority measures occurs with the qualifying factor that delays for general traffic should not be increased to a point where an intersection approaches capacity saturation.

A philosophy often adopted in continental Europe acknowledges that bus priority measures may reduce road capacity for general traffic and may impose increased delays on non-bus modes. It is accepted that general traffic can, in response, redistribute to other roads, travel at other times, not travel at all, or drivers may switch to the priority mode – bus or train. Increased delays for general traffic are, in effect, accepted as part of the “trade-off” of providing an enhanced public transport system designed to achieve desired and sustainable mode-share targets.

1.5 Comprehensive & Localised Interventions

The value of a two-pronged approach to bus priority employing, as appropriate, (i) coordinated, whole-of-route planning, and (ii) attention to localised bottlenecks, must be emphasised.

In this respect, the Public Transport Authority (PTA) of Western Australia has indicated that significant bus priority benefits will be pursued through bus priority remedies to localised bottlenecks. The introduction of bus priority interventions at the local level, and in denser inner-urban areas like Beaufort Street, Mount Lawley, will be a focus of action for the PTA to achieve the objective of significant bus travel time savings without the need to introduce large-scale, big budget infrastructure projects.

However, major bus priority projects have also been introduced in Perth, where appropriate, including such projects as the Kwinana Freeway Bus Transitway (upgraded from what was previously a dedicated, bi-directional bus lane in the freeway median) and the Rockingham – Fremantle Bus Transitway.

Notwithstanding the opportunities to introduce good “value-for-money”, localised bus priority measures, some examples from the United Kingdom indicate that, occasionally, bus priority measures may be applied on too small a scale to provide the travel time improvements necessary to attract significant passenger increases.

As a result, recently in the United Kingdom, cohesive corridor-wide bus priority plans have been able to elicit the travel time-savings and reliability demanded by a discerning market of bus users and potential bus users.

However, it is emphasised that a combination of integrated, corridor-wide bus priority measures, and localised bus priority measures aimed at specific congestion spots, will both be legitimate and valuable components of bus priority planning.

The improvement of bus travel times can be expressed in two dimensions. Bus travel times would be improved if one, or both, of the following dimensions were achieved:

� reduction in total bus journey time

� increase in bus schedule reliability

Many bus priority schemes involve comprehensive packages of measures and focus on bus service enhancement within entire areas, or corridors. In such cases, road planning and design, traffic management, and planning for all modes of transport are “orchestrated” with bus priority as a major, and transparent, objective.

This comprehensive bus priority approach to an area, or corridor, may involve road system planners, traffic managers, bus operators, and bus system planners at both the State and Local Government levels.


The Public Transport Authority of Western Australia applies a holistic approach to the improvement of bus system levels of service and should also include planning for:

� Quality of buses and other public transport infrastructure

� Fares and ticketing integration, including payment systems

� Comprehensive public transport operational integration

� Bus service user information systems

� Bus service promotion and marketing

� Vehicle parking policy, and state and local government planning.

� Road system and traffic management facilities, and state and local government planning.

� Land use planning, and state and local government planning.

� Transport system pricing policies

As an example of the necessary commitment to integrated, corridor-wide public transport system planning, the concept of a “total bus route upgrade” has recently been developed in the United Kingdom. The Traffic Director for London and London Transport Buses, bus operators, the Boroughs, the London Bus Priority Network (LBPN), the Highways Agency and the Police have all been involved. The key components of this initiative were:

� New low-floor accessible buses, running on low-sulphur diesel

� Improved on-bus passenger comfort, with better seating and greater headroom

� High quality bus stop environments, including pedestrian crossing facilities to improve accessibility

� High level of physical priority for buses

� High level of traffic signal bus priority

� Rationalisation of on-street parking and loading restrictions

� High quality of regulatory markings and signs

� High levels of enforcement, using on-bus and roadside CCTV cameras and on-street enforcement officers

� High quality of passenger information including “Countdown” real-time information (London Buses’ real time information system for bus passengers)

� High quality of bus driving and customer care

� High quality of operational management of the service

� High quality running surfaces for buses

� A marketing initiative to promote travel on the new service

It is claimed that the London Bus Initiative (LBI) is the most ambitious bus improvement program for many years. Its implementation complements the congestion charging scheme recently introduced in central London. The LBI commenced in March 2000 on 27 BusPlus routes. Bus Lane Enforcement Cameras (BLEC) have been deployed London-wide, covering 600 bus routes and 700 bus lanes. The LBI initiatives cost £60 million.

However, it must be emphasised that holistic, multi-dimensional, corridor-wide bus priority planning may not always be possible, nor appropriate. In many cases, localised bus priority enhancements may precipitate significant bus travel time improvements for passengers and contribute meaningfully to the achievement of strategic mode-share targets for public transport services.

1.5.1 Auckland – “Buses First” A further example of a coordinated and integrated planning approach to bus priority is provided by the initiatives currently being implemented in Auckland, New Zealand.

In Auckland, bus priority measures are found on eight arterials and motorways. In the Central Isthmus and CBD area, bus priority measures are available on Dominion Road, which is 8 kilometres long, and on Mt. Edam Road. Parking is prohibited during peak hours, and the kerb lane is marked for exclusive bus use. The Dominion Road bus priority lane operates from 7 a.m. to 9 a.m.


and 4 p.m. to 6 p.m. At peak hours, buses run every 3 minutes, and at off-peak hours they run at 15-minute intervals. The bus now saves 6 to 7 minutes along the 8 kilometres, and takes 18 to 19 minutes: by car, the ride is 35 to 40 minutes.

The initial evaluation reveals that the bus on-time performance and reliability has improved significantly through the day. Ridership has gone up and public perception has been generally positive. The bus travel time along Dominion Road was greatly reduced in the morning peak period, but not during the evening peak period. Officials attribute this to the fact that the bus-only lane works well in the morning because businesses are generally not open and parking violations in the bus lanes by commercial and private vehicles is not a problem. In the evening rush hours, bus lanes are often blocked by illegal parking and stopping activities and must merge with adjacent traffic. This degrades the performance of bus priority treatments.

On the strength of their initial success with Dominion Road, the local governments and the ARC want to move forward with more bus priority lanes. This will be done under a process of corridor studies that will bring wide public involvement into the process and product. The ARC has identified 11 additional arterial streets for corridor studies where bus priorities will be examined. The Buses First corridor study program seeks to implement the following seven major concepts throughout the city:

� Bus lanes

� Bus bypasses - special lanes at intersections

� Bus advance areas, or queue jumpers at traffic lights

� Signal pre-emption

� Bus stops in traffic lanes

� Peak-hour parking restrictions (clearways) and intersection upgrades

� Real-time traveller information.

Bus priority measures are designed to complement fare integration and acquiring new low-floor buses in attracting new riders.

1.6 Defining “Priority” The situation, therefore, is that significant improvements to bus travel times and, moreover, significant improvements to all aspects of the bus travel experience, require coordinated planning and action on many fronts. However, the purpose of this Guideline Module is to focus specifically on “bus priority”. In addressing this purpose, a distinction is drawn between genuine bus service “priority” measures designed to provide a special advantage to bus services and to ameliorate the delays caused by traffic congestion and measures implemented to “facilitate” bus services.

Bus service “facilitation” may be defined as the removal of existing road system barriers to efficient bus travel and the inclusion of bus-oriented design principles for new and existing roads. Active bus service “priority” relies on the introduction of road infrastructure and traffic management techniques to positively discriminate in favour of buses.

Moreover, bus priority measures may operate at the “local” level (for example, a short bus lane section in the Beaufort Street – Walcott Street vicinity in Mount Lawley) and/or at the “regional” level (eg. the Fremantle-Rockingham Bus Transitway) within the transport system

1.7 Examples of Bus Priority Infrastructure

To improve the quality of bus operations a number of priority techniques can be implemented, including the following:

Bus lanes: Allocation of dedicated bus lanes – either in the road median lane(s) or in the kerb-side lane(s) to provide priority passage to the movement of buses.

Elimination of bus lane setbacks: Improved benefit for priority vehicles as the bus lane continues to/through the intersection and there is no bus queuing in general traffic


before the intersection. However, this treatment can significantly reduce intersection capacity for other road users.

Bus advance areas: Pre-signals to allow buses to be the first in the queue at a signalised junction, without loss of intersection capacity.

Bus gates: Use of Selective Vehicle Detection (SVD) to permit access by buses only.

Rising bollards: Permit bus access only, by retracting when a bus is detected.

Selective Vehicle Detection (SVD): On detecting a bus, green signal time can be extended, or red time reduced, to eliminate, or reduce, the waiting time of the bus.

Queue relocation: To prevent down-stream blocking, traffic queues can be moved to an upstream section with sufficient capacity to contain the queues. A priority lane on this section will allow buses to overtake the queue, and travel unhindered down the previously congested section of road.

Whole-of-corridor approach: In the past, problem sites and easier sections have been looked at in isolation. The whole-route approach ensures that if bus priority is implemented in one location, dispersed traffic does not adversely affect other parts of the route. Queue relocation methods can be used. An example of this is the route 43 in London, where 12 kilometres of bus priority measures are planned to protect 63% of the bus route: this is combined with SVD signal priority at 34 junctions.

Busways: Complete segregation of buses from other vehicles.

Guideways: Complete segregation of buses from other vehicles, with guide-rails to steer the bus.

Shared-use lanes: These are generally of use on arterial roads and can result in a more efficient use of capacity, particularly if bus frequency is low. Examples of shared use include High Occupancy Vehicle (HOV) lanes and lanes that may be used by designated classes of vehicle, for example, heavy goods vehicles, bicycles and taxis.

Bus nibs: By introducing a bus nib (or boarding area jutting out from the kerb) buses do not need to pull into a stop and are unhindered by parked vehicles. Passengers do not need to step into the road to board the bus. Further, they aid passenger access, particularly on low-floor bus routes, by reducing the step height at the entrance of the bus.

Bus stop clearways & bus boxes: Clearly marked bus stop box, with strict parking restrictions. They may be enhanced by coloured road surfaces.

The foregoing techniques for providing bus priority have been implemented successfully in many bus priority schemes. These, and other, techniques form the focus of this Guidelines Module.


2. Regional-Level Priority 2.1 Transit Malls Transit malls are streets that are transformed to give priority access to buses, eliminate most, or all, private vehicles, and enhance pedestrian environments including waiting areas for bus patrons.

Figure 1: Chicago’s State Street as a transit mall (above) and a mixed traffic street (below).

Figure 2: Transit Mall in Portland, Oregon

2.2 Bus Transitways (Busways)

2.2.1 Exclusive Bus Transitways (Selected information on bus transitways has been drawn from the “Bus Transitway Planning Manual” prepared for the Department for Planning & Infrastructure in January 2002. For further information refer to that Manual)

A “busway” or “bus transitway” may be defined as a dedicated right-of-way for buses, usually constructed as a separate bus facility in a freeway reserve, or on a new alignment through a greenfields area.

Bus transitways are dedicated to line-haul bus services and offer:

� High standard carriageways

� Physical separation from other traffic

In addition, they often provide:

� High-speed design

� Grade-separated access

Busways, whilst relatively uncommon, can offer buses an unimpeded, relatively high-speed environment where bus delays are minimised and schedule adherence is enhanced.

A busway may be grade-separated, or at-grade, or a combination of both. Running times may be decreased by 50%, or more, compared with a conventional bus service. However, costs are relatively high and are dependent on the degree of grade-separation used, the use of traffic signal priority, the number and quality of specialised on-route stopping facilities, and other busway system components.

A transitway that, through its physical design and user regulatory controls, is accessible only to approved buses and emergency vehicles. Design characteristics include:

� Physical barrier-separation from general traffic which prevents entry from adjoining traffic lanes.


� Access to the transitway is limited to approved transitway vehicles operated by approved transitway drivers.

� Vehicle entry and exit often occurs only at designated transitway stations.

� Slip lanes and interchanges provide appropriate acceleration and deceleration lanes.

� Grade separation applies for all transitway crossings by general traffic.

Figure 3: Typical Transitway Grade-Separation

OR

Figure 4: Kwinana Freeway Busway including Bus Transfer Station at Canning Highway

Interchange and Busway Entry/Exit Ramps, Perth, WA

Figure 5: The Barrier-Separated, Two-Lane Kwinana Freeway Busway, Perth, WA


Figure 6: South East Busway, Brisbane, Queensland

Figure 7: Controlled ramp entry to the Woolloongabba Busway, Brisbane, Queensland

The two major examples of busway systems in North America are located in Ottawa, Canada and Pittsburgh, Pennsylvania. The busways carry in the vicinity of 300,000 passengers per day.

Figure 8: Busway facilities in Ottawa, Canada

Figure 9: South Transitway, Ottawa, Canada as seen from the hospital on-line station. The

busway is typically a 2-lane roadway, but branches to 4-lanes approaching busway stops.

Figure 10: Southwest Transitway, Ottawa, Canada at an on-line station built with grade-

separation from a major street above. The transitway system is restricted to buses only.

Figure 11: Ottawa busway showing high-quality bus stop facilities and by-pass lanes for buses

passing stopped vehicles.


Figure 12: Ottawa busway showing grade-separated passenger access facilities and route alignment adjacent to existing general traffic.

Figure13: The First Avenue downtown bus tunnel in Seattle, USA includes direct bus ramps on either

end of the tunnel. Within the tunnel, five on-line stations provide side platforms for up to four buses

to load and unload simultaneously.

Figure 14: The Pittsburgh busway system provides express service between on-line stations at

separations of 0.5 to 1.2 miles. Some stations allow passengers to cross the busway at a

crosswalk. Parallel bus bays are provided from separate lanes on each side of the busway.

Figure 15: Example of a barrier-separated, exclusive busway in the USA

Figure 16: Exclusive section of busway in Curitiba, Brazil with specialised passenger

waiting facilities adjacent to busway.


2.2.2 Guided Busways A variation on conventional exclusive busways (bus transitways) is the Guided Busway, a design concept that developed in several cities from the 1980s.

The Guided Busway combines features of a rail operation, with a purpose-built track that removes the requirement for the bus operator to steer the bus.

Adelaide, South Australia inaugurated a Guided Busway – the O-Bahn – in 1986. The O-Bahn comprises concrete track components used by conventional buses that have been fitted with horizontal, solid rubber guide rollers forming the track guidance system.

Figure 17: Guided Busway Track (O-Bahn) in Adelaide, South Australia

(The guided busway requires less space than other busways. Disadvantages include inability to

bypass a stalled bus and the need for buses to be fitted with horizontal guidance equipment.)

Figure 18: The Adelaide Guided Busway Near a Point Where Buses Exit/Enter the Busway

The advantages of a Guided Busway compared with a conventional busway may include:

� Higher standard of ride comfort

� Reduced engine noise due to less reflection of sound in the absence of conventional road pavement

� Reduced tyre noise

� Reduced busway cross-section

� Potential routing and cost advantages due to the capacity to use narrow rights-of-way

� Reduced driver stress and fatigue

� Passenger approval similar to that for rail-based systems

A major disadvantage is that bus breakdowns may shutdown the entire system until the disabled bus is removed.

Figure 19: The O-Bahn in Essen, Germany in an abandoned tramway alignment.

Figure 20: In Leeds, England, a guided busway has been developed to provide extensive separation of buses from other traffic.


2.2.3 Semi-Exclusive Transitways A semi-exclusive transitway is one that, due to physical design and regulatory controls, can be crossed at-grade by general-purpose vehicles only under controlled conditions prescribed by the road traffic code 2000. General-purpose vehicle entry from adjacent lanes to a semi-exclusive transitway is generally not permitted. Design characteristics include:

� Physical, or barrier-separation, from general traffic that prevents, or restricts, entry from adjoining traffic lanes.

� Access to the transitway is limited to approved transitway vehicles with approved transitway drivers.

� Approved vehicle entry and exit allowed at controlled, “at-grade” intersections as well as at stations and interchanges that provide appropriate acceleration and deceleration lanes.

(Refer to companion guidelines – “Design and Planning Guidelines for Public Transport Infrastructure: Traffic Management & Control Devices”)

� General traffic crosses the transitway at controlled at-grade intersections.

Semi-exclusive transitways may be located in the roadway median kerbside lanes laterally on one side of the roadway, or on both sides of the roadway.

2.2.4 Non-Exclusive Bus Transitways A non-exclusive transitway is a carriageway where the physical design and vehicle access regulations may permit a range of vehicles, other than buses, to enter and travel along the transitway for a limited, or extended, distance.

Design and operational characteristics include the following:

� Physical separation from general traffic is not generally required, or provided.

� Access to the transitway by general traffic and cyclists is permitted at specific locations for specific purposes, for example, in making left or right turns at

intersections and gaining adjacent property access.

� A bus movement, laterally between the transitway and adjacent lanes, is physically unrestricted but may be subject to pre-determined operating procedures.

� General traffic is permitted to cross the transitway where required, including at signalised non signalised at-grade intersections. General traffic is also permitted to enter driveways or kerbside parking bays.

Non-exclusive transitways may be located in the median lane(s), on either kerb lane, or on both kerb lanes, of the roadway.

2.3 Bus Lanes Bus lanes separate buses from other traffic, enabling them to avoid traffic congestion. By using the lanes, buses have shorter journey times and are better able to keep to their timetables.

The lanes are clearly marked (usually) kerb-side lanes and may operate in the direction of the peak traffic flow. Some of the lanes have coloured pavements for easy identification. Parking or stopping on the lanes is prohibited during the times they operate.

Bus lanes may be differentiated with respect to several major characteristics:

� Location within the roadway (kerb-side; median; or centre-lane)

� Concurrent-flow or contra-flow operation

� Method of separation from general traffic (barrier-separated; line-separated)

� Time of operation (24-hour; 12-hour; peak-period only)

� Vehicle eligibility (buses and emergency vehicles only; or buses and other high occupancy vehicles, including taxis and private cars) (Note: Under the Australian Road Rules, 2000, emergency vehicles can use Bus Lanes)


Figure 21: Typical Layout of Median Bus Lane

Figure 22: Typical Contraflow, Kerb-Lane, Bus Lane

Figure 23: Typical Contraflow, Median-lane, Bus Lane

Figure 24: Typical Single, Reversible, Median Lane, Bus Lane

Figure 25 (A & B): Typical Two-Way, Median Lane, Bus Lanes

(Median Bus Lanes, Causeway Bridge, Perth,

WA)

A

B


2.3.1 Bus Lane; Concurrent-Flow; Kerb-Side

At the strategic level, the provision of dedicated road space for buses permits relatively high speed, unimpeded travel, usually over an extended length of the road network.

A major benefit of bus lanes is the significant additional schedule reliability that they offer. The construction costs will vary considerably depending on whether an existing traffic lane is converted to operate as a bus lane, or whether a new, purpose-built bus lane is constructed.

Concurrent-flow bus lanes are generally located in a kerb-side lane and typically operate during peak-periods such that the lane may be used by general traffic, or for vehicle parking, during non-peak periods.

Figure 26: Concurrent-Flow Bus Lane, George Street, Sydney

Figure 27: Example of a Concurrent-Flow Bus Lane in Paris, France.

Based on work undertaken for the Better Public Transport 10-Year Plan for Transperth, 1998-2007, it was recommended that an

exclusive bus lane could be justified where a bus service carried a minimum of 2,000 passengers, and 40 buses, per peak hour.

Figure 28: Concurrent-Flow Bus Lane in London’s with Bus Stop, Angled Boarders, and

Contrast Coloured Pavement

A number of European cities provide physically separated bus lanes along arterial roads. As an example, Paris has numerous bus lanes on major arterial streets. In figure 29, the right-hand kerb is for bus loading and buses are operating with the flow of adjacent traffic on the left. A parking lane is provided along with a planter to separate the concurrent-flow bus lane from adjacent traffic. Pedestrians are given designated crossings (shown in the foreground). No bus breakdown areas are provided along these lanes that generally extend less than 250 metres through areas where bus service has experienced congestion problems. Buses are not allowed to turn out of the lane.

Figure 29: Separated Arterial Bus Lane, Paris, France


At intersections where arterial bus lanes cross busy streets, pavement markings are often used to alert motorists to oncoming buses. A planter with trees separates the “with-flow” bus lane shown above from adjacent traffic. Bollards are also used to differentiate the bus lane from the footpath.

Figure 30: Bus Lane Identified by Pavement Marking, Paris, France.

2.3.2 Permitted Turns Across Kerb-Side Bus Lane

Where a bus lane continues up to, or through, an intersection, general traffic is typically allowed to enter the bus lane for a limited length of travel (100 metres under the Road Traffic Code 2000 in Western Australia) for the purpose of making a legal left-turn or right-turn. It is also permitted to enter a bus lane for the purpose of legally accessing a driveway. Figure 31 shows permitted turns in relation to the bus lane in Hampton Road, Fremantle.

Figure 31: Permitted Turns for General Traffic: Hampton Road Bus Lane, Fremantle

(Source: Public Transport Authority, WA)

2.3.3 Bus Lane; Concurrent-Flow; Central Lane

For a number of reasons, for example, to position buses efficiently to turn or proceed through downstream intersections, a concurrent-flow bus lane may be located in the centre lane of a roadway, flanked by general traffic lanes on either side.

The following example is from Perth, WA: Figure 32: Bus Lane in Central Traffic Lane,

Fitzgerald Street, Perth (A, B & C)

A


Further examples of bus lanes that have been implemented in centre traffic lanes in city streets exist in many cities. The following two examples in Sydney, NSW and Chicago, USA provide further illustration of the concept.

Figure 33: Bus Lane in the Centre Lane of the Roadway near the Town Hall Bus Station in

Sydney, NSW.

Figure 34: Bus Lane in the Centre of a Street (State Street, Chicago before the street was converted to a bus mall in the early 1980s)

2.3.4 Bus Lane; Concurrent-Flow; Median

Whilst most bus lanes are located in a kerb-side lane, there are many examples of concurrent-flow bus lanes operating in the median lane of a freeway, highway, or arterial roadway.

Bus lanes adjacent to the median generally operate line-haul services where buses do not stop, or stop infrequently. Traffic turning left at intersections, or to gain access to properties does not impede buses.

Other factors that may facilitate a median-lane location include:

� The road has major access control

� Intersection spacing is > 500 metres

As bus passengers need to cross general traffic lanes to access a median bus lane, it is essential to address pedestrian safety issues and bus stop passenger storage issues.

Due to the foregoing factors, median bus lanes generally require higher bus flow warrants than kerb-side bus lanes.

B

C


The Public Transport Authority assesses bus lane warrants by considering the merits of each case. The following factors are priorities to be considered:-

� Volume of buses and passengers perhour

� Delays experienced by buses

� Proximity of services to destinations

� Community benfits of bus lanes

In Perth, WA, as part of the “Access to the City for People” initiatives, new bi-directional, median bus lanes were introduced on the Causeway Bridge providing for bus priority access to/from the Perth Central Business District (CBD).

The bus lane initiative (and other initiatives) was underpinned by construction of the Graham Farmer Freeway and Tunnel, which significantly reduced traffic volumes on the Causeway Bridge, making it possible to introduce the bi-directional bus lanes without reducing road capacity for general traffic.


Figure 35: Median Bus Lanes, with Bus Signals, on Causeway Bridge, Perth, WA



Figure 38: Median Bus Lanes and Bus Transfer Station, Causeway, Perth.


2.3.5 Concurrent-Flow Bus Lane Set-Back

Bus lanes may operate continuously between, and through, intersections. However, where intersection capacity approaches its limit, with significant left-turning traffic, and where bus volumes are not high, the bus lane may terminate before the intersection stop line to permit general traffic to use the bus lane.

As an example of the effects of bus lane set-back conditions, Olfield et al. (1977) researched the optimum set-back for bus lanes in the United Kingdom and concluded that it increases “with increasing degree of saturation and is proportional to the (traffic signal) green-time. It is roughly 2.5 metres


per second of green-time at the 95% level of intersection saturation, and 1.0 metre per second of green-time at the 70% level of saturation.”

However, it is emphasised that, in Australia, general traffic is permitted to enter a bus lane for the purpose of making a turn or to enter a driveway. Therefore, there is no need to truncate a bus lane on the approach to an intersection to make provision for general traffic to enter the lane to undertake a turning manoeuvre.

2.3.6 Bus Lane; Contra-Flow Contra-flow bus lanes allow buses to travel in the opposite direction to the general flow of traffic. In the USA, contra-flow bus lanes are extensively used on freeways. However, in Britain and Europe they are more typically used in conjunction with one-way street operation to avoid the need for deviation of a bus route, or to shorten a bus route.

Where an imbalance exists in the flow of general traffic (ie. a pronounced tidal flow) a traffic lane may be taken from the non-peak direction and allocated to buses travelling in the peak direction. The travel time benefits of contra-flow bus lanes are similar to those for concurrent-flow lanes.

Contra-flow bus lanes on freeways are usually located in a median lane to avoid conflicts with traffic entering or exiting the freeway.

Stand-by incident clearance crews may be required to ensure that a bus breakdown does not block the contra-flow bus lane.

Special consideration should be applied to the potential road safety implications of buses travelling against the flow of adjacent general traffic lanes. This should include clear freeway signage and demarcation of the contra-flow lane. In some cases, moveable barriers have been deployed to safely manage the contra-flow movement and to provide for reversible flow to accommodate alternating directions of peak traffic flow.

Furthermore, on some roads, a contra-flow bus lane may involve pedestrian safety hazards where pedestrians crossing the road may not be aware of the contra-flow

movement of another traffic stream. Pedestrian safety fencing may be required

Contra-flow bus lanes may operate in either kerb-side or median lanes. Operation in a kerb-side lane typically occurs in a one-way street, allowing bus operations counter to the direction of the general traffic flow. Figure 40: Contra-Flow Bus Lane: Layout where

Buses Join a Median Reserved Lane

P E A K F L O WD I R E C T I O N

U N D E R- U T I L I S E DD I R E C T I O N

BUSES

L I N E O F P O S T S

T A P E R E D T OM E D I A N

BUS

Many contra-flow bus lanes are short-length facilities within town centres. However, on major highways or freeways, they may also be employed to provide travel-time benefits over the line-haul section of a bus journey.

Figure 41: Indicative Layout of a Contra-Flow Bus Lane in a Freeway Median. This Lane

Operates as a “Zipper Lane” with Moveable Barrier Separation.


Figure 42: Illustration of Deployment of a Moveable (“Zipper”) Barrier to Facilitate Contra-

Flow Bus Lane Operation

Figure 43: Contra-Flow “Zipper” Bus Lane in Operation in the USA

2.3.7 Short Bus Lanes at Traffic Signals

Short bus lanes are, in effect, a shared left-turn and through-lane at traffic signals, where the left-turn is for all vehicles and is by way of a slip-lane, and the through movement is for buses only. The short section of the through-lane beside the corner island is, therefore, a "short bus lane". These short bus lanes may have a contrast-colour pavement so that all users can easily identify them. Such lanes have been deployed in Perth – for example, on the approach to the Canning Highway Interchange Bus Transfer Station – and in Adelaide, South Australia. (Passenger Transport Board, South Australia, 2002)

The advantages of short bus lanes are that buses can join free-flowing, left-turning traffic to avoid queues in the adjacent through-lanes, before stopping at the intersection stop line.

Short bus lanes can be used in conjunction with "B" lights. This provides for reduced delays for buses, and better schedule adherence and reliability for public transport users. Disadvantages are that a through-lane is not available for other traffic, increasing queue lengths and delays. However this is counteracted to a large degree by the approach lane also acting as a left-turn lane for all vehicle types.

Short bus lanes have generally been quite successful.

A further example of a short section of bus lane allowing access to a bus - rail interchange facility exists at Midland, Western Australia. The following figure identifies: (A) the short section of bus-only lane on the far side of an intersection; (B) the approach to the turn-in to the bus terminus area; (C) the right-turn bus turn-in to the terminus; and (D) a bus utilising the bus lane to reach the bus – rail interchange.

The short bus lane benefits buses because, beyond the turn-in to the bus terminus, a rail level crossing can cause vehicle queues that may block buses arriving at the bus terminus. The bus-only, colour-contrasted bus lane ensures ready access for buses to the bus – rail interchange at all times.

Short bus lanes – and other localised bus priority initiatives – are likely to represent a significant and cost-effective focus for future bus priority intervention in Perth, to achieve benefits for passengers.


Figure 44 (A, B, C, D): Short Bus Lane at Midland Bus – Rail Interchange, Perth, WA

2.3.8 Enforcement of Bus Lanes Priority lanes can only work if respected by other road users. A parked vehicle in the lane forces priority vehicles to enter a non-priority lane and queue with other traffic. This can negate any benefits obtained from the priority measure.

Non-priority vehicles travelling in a priority lane will increase queues at junctions, delaying priority vehicles and reducing benefits. Manual enforcement is costly, though some innovations, including traffic wardens travelling on buses to deal with offenders, have improved bus lane efficiency in the United Kingdom.

Figure 45: Parked vehicle obstructing bus lane operation in London, England.

Automated enforcement systems are now in use in a number of cities. These initiatives increase the level of offence detection and, therefore, offer stronger deterrence. The initiatives include:

� Bus mounted cameras

� Roadside CCTV

� Roadside fixed cameras

A

B

C

D


Figure 46: Camera Enforcement of Bus Lane, Sydney, NSW.

Such systems require initial purchase of equipment, the setting up of an operations centre and route signing, both regulatory and warning.

The importance of enforcement cannot be overstated. It has been claimed that, if all violations of bus lane facilities were eliminated, the efficiency of bus lanes in London could improve by up to 50%.

As part of the London Bus Initiative (LBI) all 700 bus lanes in London will be enforced by on-bus, bus lane enforcement cameras (BLEC). Complementary roadside CCTV camera systems that can be used for enforcement of bus lanes, bus stops, and waiting and loading regulations are also being deployed. (Gardner, 2001)

Figure 47: London’s On-Bus, Bus Lane Enforcement Cameras (“context view”)

Figure 48: London’s On-Bus, Bus Lane Enforcement Cameras (“close-up view”)

Figure 49: On-Street Camera Enforcement - Borough CCTV Camera in London

Self-enforcement design features can make bus priority easier to enforce and reduce the need for other enforcement resources. Features include:

� Physical entry treatments to deter vehicles from accidentally, or deliberately, entering a bus priority lane, eg. chicanes, islands and bollards.

� Conspicuous lane markings and signing to help deter the unauthorised use of priority features.

� Entry to a bus lane direct from a bus stop.

� Entry to a bus lane controlled by features such as bus-activated signals and rising bollards. (Care must be taken to ensure that buses are not delayed or “trapped” by such devices).


2.4 Freeway Access Ramps It is not always feasible, nor beneficial, to allocate an extended bus-only lane on a major highway, or freeway, especially where bus flows are not large, or where the freeway flows are relatively uncongested. However, bus access to the freeway itself may be significantly delayed by traffic congestion on mixed-traffic freeway entry ramps, whether or not ramp-metering devices are in operation to regulate entry flows to the freeway. This may be overcome through the construction of a bus-only ramp, or by providing a bus lane on the freeway access ramp, allowing buses to bypass traffic queues.

Linking city centre bus lanes to freeway entry/exit ramps can also provide significant bus travel time improvements. The Seattle “Blue Streak” project is an example of this type of bus priority. It reduces passenger two-way journey times by about 15 minutes.

Figure 50: Typical Layout of a Ramp Meter Bypass Lane

Figure 51: Example of a Bus-Only Freeway Access Ramp, with General Traffic Held by

Signalised Ramp Meter, USA.

Figure 52: Typical Layout of an Exclusive Ramp

Figure 53: Dedicated Freeway Entry/Exit

Ramps for the Kwinana Freeway Busway (at Canning Highway Interchange)


2.5 Transit Lanes Multi-purpose transit lanes provide enhanced service to eligible classes of high occupancy vehicle (HOV). Transit lanes include access for buses, but are not dedicated to buses alone.

Transit lanes are typically justified as facilities to maximise the person-throughput of a section of the road network.

For the USA, Nuwursoo & May (1988) suggest that Transit Lanes should provide:

� A minimum travel time saving of 2 minutes per 3-4 kilometres

� A minimum total travel travel time-saving of 7 minutes per journey

� A minimum highway level-of-service “B” (ie. max. flow of 1000 vehicles per hour) so that they offer a clear benefit compared with non-Transit Lanes

These service characteristics and benefits are required to make transit lanes sufficiently attractive to compete with private car travel in general traffic lanes. However, enforcement is a major issue for transit lanes, as many non-eligible vehicles seek to use them.

If a sufficiently high level-of-service can be maintained, transit lanes can offer significant benefits to buses, usually in an arterial road environment.


3. Local-Level Priority 3.1 Bus Nibs The importance of the bus stop in the bus (and passenger) journey should not be under-estimated. In terms of journey times the boarding and alighting of passengers at bus stops comprises a significant part of the overall journey time. Also the effectiveness of bus priority measures can be compromised by delays to the bus in moving into and out of bus stops along a route.

Kerb-side parking (often illegal) causes consistent problems for bus operation and can cause significant cumulative delays, especially in busy central business districts and suburban town strips.

A device for alleviating this problem is the bus nib (or bus “boarder” or “reverse embayment”) where the kerb is built out into the roadway making it easier for buses to stop for passengers then move back into the traffic flow. General traffic is required to stop behind a bus that is loading/unloading passengers.

Figure 54: Bus Nib in Hay Street (Perth, WA)

Figure 55: Bus Nib in Hay Street (Perth, WA)

Figure 56: Bus Nib, Shenton Park (Perth, WA)

Figure 57: Bus at Bus Nib, Shenton Park (Perth, WA)


Figure 58: Bus Nib (called a “Boarder” in UK) with Marked Box

Figure 59: Bus Loading Passengers at a Bus Stop with Bus Nib (or Boarder) in Europe

3.2 Bus Stop Run-Ins and Run-Outs

Where circumstances permit, buses may be provided with deceleration and acceleration lanes leading into, and out of, embayed bus stops to enhance the standard provision for entry and exit tapers at embayed bus stops. In such cases, run-in/run-out lengths would be greater than standard entry/exit tapers.

3.3 Bus Advance Areas & Pre-Signals

A bus advance area is a priority measure that enables buses to go to the front of the queue at traffic lights. An extra set of traffic lights, with a special bus signal, is installed about 50 metres before the intersection to hold other traffic back while buses go to the front. A bus lane is provided as far as the pre-signals.

The pre-signal and bus advance area effectively re-order the traffic stream by giving buses priority over other vehicles to reach the main intersection traffic signals. The measure is particularly useful for right-turning buses.

Figure 60: Bus Advance Area & Pre-Signal

Figure 61: Bus Advance Area & Pre-Signal


In essence, a bus advance area functions as the converse of a bus lane set-back. A set-back provides for the termination of a bus lane to allow general traffic to use all available lanes at an intersection. In the case of a bus advance area, the general traffic is held back to allow buses priority in occupying any traffic lane at the main intersection.

Providing a bus advance area can also enhance traffic-metering. The bus advance area may be particularly applicable on the approaches to a town centre where, because of constraints such as narrow road width and commercial loading requirements, bus lanes, or busways, cannot be introduced.

Bus advance areas have the advantage that bus journey-time savings can be achieved throughout all periods of the day, 7 days a week or, alternatively, this type of bus priority measure may be operated only when congestion problems occur.

Figure 62: Bus Advance Area – Shepherd’s Bush Green, London, UK

The following images illustrate the effect of traffic-metering, involving pre-signals and bus advance, in protecting buses on the approach to Acton Town Centre in London. The intervention has been recently implemented as part of the London Bus Priority Network (LBPN) scheme on BusPlus Route 207.

Figure 63: Traffic-Metering, with Pre-Signals and Bus Advance, Protects Buses Approaching

Acton Town Centre, London, UK.

(A) Traffic re-located / bus protected by bus lane

(B) Bus travelling through pre-signal to bus advance area (reverse angle to above image)

(C) Pre-signal for bus (on “red” for general traffic) allows bus to “queue-jump”

A

B

C


(D) Bus travels through congested town centre due to pre-signals and bus advance measures

(Source: Gardner, 2001)

3.4 Queue Re-Location Bus Lanes and Pre-Signals

Queue re-location bus lanes are used to provide a concurrent-flow bus lane at a point where there is sufficient space within the roadway rather than at the point where traffic congestion occurs. General traffic is restricted by either being forced to merge following loss of a lane to the buses, or it is restricted by introduction of a set of pre-signals.

Downstream of the merge point, buses and general traffic may be re-combined, or the bus lane may be permitted to continue to the next intersection. In either case, the roadway operates without major delays to buses.

This measure is similar to the Bus Advance & Pre-signals method for bus priority approaching congested intersections. However, the difference is that Queue Re-location Bus Lanes with Pre-signals is a technique applied where mid-block road circumstances are suitable, but where space constraints may prohibit a similar approach near the intersection.

Figure 64: Queue Re-Location with Pre-Signals (“Traffic-Metering”) Hanwell, London

(Source: London Transport Buses)

In the United Kingdom, these traffic- metering techniques reduce congestion on narrower sections of road, allowing traffic to flow more freely. Buses gain from the bus lane on the wider section of the road, and from the freer flowing traffic on the narrower road sections.

Traffic-metering is being applied along whole bus routes in the United Kingdom (end-to-end) as part of a “total route control strategy” providing efficient movement of buses throughout the route, with linked and balanced queue-control locations at regular intervals.

3.5 Queue-Jump Lanes Queue jump lanes provide the opportunity to re-allocate road space to provide genuine priority to buses at major congestion points. Queue-jump lanes are generally much shorter in length than bus lanes and may be achieved by:

� Constructing a new short section of lane for the exclusive use of buses

� Removing kerb-side parking to permit buses to use this section of the carriageway

D


� Forcing cars to merge prior to the congestion point so buses can bypass them.

Guidance in the USA (Texas Transportation Institute, 1996) recommends queue-jump lanes at arterial street intersections in situations where:

� There is a high-frequency bus service with a maximum average headway of 15 minutes.

� Traffic volumes exceed 500 vehicles per hour in the kerb lane during morning or afternoon peak periods.

� The intersection operates at a level of service of D, or worse.

� Cost is acceptable and land acquisition is feasible.

Figure 65: Typical Queue-Jump Lane

OR

Figure 66: Queue-Jump (or By-Pass) Lane, UK.

(Source: London Transport Buses)

Figure 67: Queue-Jump with Signals, The Netherlands

3.6 Bus-Only Streets Where traffic has been completely removed from a street, an exemption for buses, allowing them passage through the otherwise traffic-free street, may be vital to


the provision of good bus services to passengers.

Bus-only streets generally provide access to only to public transport vehicles and pedestrians. However, special classes of vehicle may also be permitted entry, for example, emergency vehicles, taxis and delivery vehicles, perhaps with restrictions on the time-of-day when deliveries are permitted.

The potential applications for this form of bus priority link include:

� Bus mall

� Suburban connector

� Approach to shopping mall, or other major bus trip generator

� Short link that would otherwise entail significant delays or circuitous bus travel

� Typically designed for bus-only

Typical benefits include:

� Limited cost (usually)

� Readily enforced

� Reliable travel time

� Little operational interference from non-priority vehicles

� Small investment can yield substantial benefits

� Benefits bicyclists as well

Figure 68: Typical Bus-Only Street or “Priority Link”

The introduction of bus-only streets tends to be associated with broader city planning and urban design objectives.

Bus-only streets can:

� Provide a city terminus area for visitors to a city centre

� Improve passenger interchange between bus services

� Enhance bus travel time reliability and reduce travel time delays

The design and construction of bus-only streets may need to consider:

� Availability of parallel routes to accommodate displaced traffic (the parallel route need not necessarily be of the same, or adequate, capacity)

� Access for commercial vehicles to adjoining land uses

� Design of entry/exit points to discourage or preclude entry to general traffic

� Reduction of bus speeds to address potential bus – pedestrian conflicts

Whilst many bus-only streets are associated with urban planning objectives for central


city precincts, other types of bus-only street may include:

� An exclusive approach to a bus station, or terminus

� Bus loop for service turn-around and/or access to a bus layover area

� Short connector links to facilitate a direct and continuous bus route.

3.7 Other Bus-Only Connector Links & Bus Gates

Bus-only connector links provide access for buses between residential (or other) land use cells without the same connectivity being also provided to general traffic.

High levels of enforcement may be required for the success of this treatment in relation to general traffic compliance.

Should there be high levels of general traffic non-compliance, a potential counter measure is the installation of a series of speed cushions on the bus link to make non-bus use uncomfortable. Another potential treatment is the use of a “bus gate”.

Figure 69: Layout of Bus Link & Bus Gate

(Source: DETR, 1997)

Figure 70: Bus-Only Rail Crossing at Fitzgerald Street, Perth

Figure 71: Bus-Only Link, Kardinya (Perth, WA)


Figur72: Bus-Only Link, Kardinya (Perth, WA) Showing Restrictive Signage


Figure 72: Two Views of Bus-Only Bridge, Shenton Park, WA

“Bus Gates” are short sections of bus-only, or bus and other permitted vehicle-only, sections of road. Bus access to pedestrian streets gives buses considerable advantages over the car by being able to deliver passengers directly into, for example, shopping areas. Such schemes are widespread in town centres in the United Kingdom and are used successfully as part of area-wide access strategies. The most notable examples are the bus gates introduced in Oxford as part of the Oxford Transport Strategy.

The bus gate allows buses to access a section of the street network, but presents a physical barrier to other vehicles. The “gate”, or barrier, may be in the form of a pit where a track is provided to match the wheelbase of the bus, but not narrower-tracked vehicles such as private cars.

Alternatively, selective vehicle detection (SVD) may be used to lower or raise a barrier that allows the passage of buses.

By using this device, buses may benefit from a less circuitous route through residential areas without encouraging unwanted general traffic movements.

3.8 “No -Turning” Exemptions for Buses

Where general traffic is restricted from turning into a street, the provision of a “no-turning” exemption for buses may ensure bus service continuity without imposing a circuitous route and additional journey time on bus public transport services.

The “no-turning exemption” is a bus priority measure that has been used for many years and is widespread in many countries. (This exemption is addressed under regulation 72 of the Western Australian Road Traffic Code 2000)

Figure 73: Bus-Only, Right-Turn Exemption, Wellington Street (eastbound), Perth, WA

Figure 74: Buses Turning at Right-Turn Exemption, Wellington Street, Perth, WA


3.9 Bus Acceleration Lanes One common source of delay to buses is the requirement to undertake right-turn movements at unsignalised T-intersections.

To reduce this form of delay to buses, traffic management measures such as roundabouts or signals may be introduced at T-intersections. However, such measures are often not feasible due to cost and/or specific site restrictions. As a result, alternative traffic management measures need to be investigated.

The delays incurred in making a right-turn into a divided roadwidth median also affects bus route planning decisions prior to the introduction of services. As a result, bus services may be forced to use routes that are less desirable from a bus passenger perspective because the otherwise preferred route includes a difficult right-turn manoeuvre that may also be potentially unsafe.

A beneficial measure may involve the introduction of acceleration lanes along the central median to allow buses to accelerate easily and join the main stream of traffic once it reaches the central median gap.

However, Main Roads WA’s position with respect to acceleration lanes is that:

� Proposed acceleration lanes should be designed to accommodate all normal types of vehicles, including buses

� Acceleration lanes should be designed in accordance with Austroads Standards unless there are exceptional circumstances that justify an alternative

A study of three intersections, undertaken for the DPI in Western Australia, estimated appropriate acceleration lane lengths for right-turning buses, on the terminating road, and for varying speed environments:

Table 1: Suggested Bus Acceleration Lane Lengths

Speed (km/hr) Desirable Minimum

60 130m 108m

70 180m 165m

80 260m 260m

(Source: Department for Planning & Infrastructure, 2002)

3.10 Supportive Interventions The enhancement of bus travel times requires examination of all time components of the bus journey, especially including bus stopping time. For example, in Australian conditions, about 25% of the bus journey time can be consumed whilst buses are stationary at bus stops. (Ogden & Taylor, 1996)

Therefore, whilst not exclusively a bus “priority” measure, the following traffic and bus service management interventions are supportive of “affirmative action” bus priority measures and may be essential if an investment in bus priority is to achieve tangible improvements in bus travel times.

3.10.1 No-Stopping Restrictions on Priority Bus Routes

Imposing “No Stopping” restrictions can significantly improve bus travel times on high volume, or priority, bus routes.

This approach is successfully employed on the London Red Route Network (LRRN) and the London Bus Priority Network (LBPN).

Restrictions may be applied throughout the day, or as a peak-period bus travel time enhancement measure.

3.10.2 Bus Stop Clearways As with bus lanes, stopping or parking on bus clearways is prohibited during peak traffic times.

Prohibition of the parking or standing of a vehicle at bus stops has been successfully applied in the United Kingdom to avoid conflicts between buses and parked vehicles.

In South Australia, creation of a Bus Zone is considered the preferred intervention, as it is more obvious. (Passenger Transport Board, South Australia, 2002)

Beaufort Street, Inglewood provides a Perth-based example of a Bus Stop Clearway successfully contributing to priority flow for buses.


3.10.3 Priority Route Enforcement, Parking & Infringement Fines

To ensure that vehicle parking/standing prohibitions are effective on designated bus routes and at designated bus stops, appropriate enforcement programs and penalties are required to serve as effective deterrents.

(Refer to Section 2.3.8 relating to enforcement of Bus Lanes.)

3.10.4 Bus Stop Re-Location The siting of bus stops can significantly influence bus travel times and should consider:

� Adjacent land uses

� Traffic volumes

� Passenger demand

� Road geometry

� Existence of bus priority signalisation

Where possible, bus stops should be located down-stream of an intersection, especially an intersection with bus priority signalisation.

3.10.5 Reduction in Bus Stopping Time Advanced fares payment and passenger information services can provide support for the travel-time savings achieved by the introduction of bus priority measures.

For example, research in the United Kingdom (Cundill & Watt, 1973) found that average dwell times for different types of bus operation varied as follows:

� 1 sec./passenger for a 2-person-operated bus

� 2.3 sec./passenger for a 1-person-operated bus with “automatic” fare ticketing machine

� 6.6 sec./passenger for a 1-person-operated bus with “manual” payment of individual fares

Significant dwell-time reductions can be achieved through a combination of operational initiatives, including:

� Improved efficiency of fares payment

� Improved ticketing systems

� Real-time passenger information at bus stops to reduce bus driver queries.

However, it should be recognised that there are many other factors that influence average bus dwell times at bus stops, including:

� Whether the service is operating in a peak or inter-peak period.

� Bus design features, especially doors.

� The type of bus fare ticketing systems used.

� The degree to which information is sought from drivers (this is often greatest in localities that attract many tourists and non-regular users of buses).


4. Planning & Justifying Bus Priority Infrastructure 4.1 A Project Prioritisation &

Evaluation Model (PPEM) The Public Transport Authority (PTA) is responsible for developing and delivering a number of different Bus Priority projects ranging from simpler, smaller-scale, projects like roundabouts, traffic signalisation works, and acceleration lanes to more complex and larger-scale projects, for example, dedicated bus transitways, bus lanes and queue-jump lanes, and public transport interchanges.

To assist the PTA in its activities relating to project justification, specification and implementation, a Project Prioritisation and Evaluation Model (PPEM) has been developed and would be made available by the PTA to assist authorities and organisations in the evaluation of alternative projects for the provision of public transport priority.

Essentially, the PPEM provides an evaluation framework for the before-and-after assessment of potential public transport projects and includes examination of key public transport performance criteria, for example:

� Bus movements

� Bus travel time improvements

� Passenger loading increases

� Passenger time savings

� Passenger benefits

The range of user and operator benefits is compared with the range of incremental net costs to assess project value-for-money and priority for implementation.

The PPEM may be applied to all, or a selection of, bus priority projects under consideration. The framework can be used to:

� Assess the best bus priority option from a range of alternative interventions being considered for a particular location.

� Establish priorities between competing projects to achieve maximum value-for-money.

The evaluation framework includes nine components, addressing:

� Project Evaluation Framework

� Project (or type of intervention)

� Parameters for assessment

� INPUT - Project benefits

� INPUT - Bus operating cost savings

� INPUT - Project costs

� Benefit/Cost Ratio

� Sensitivity

� Externalities

Refer to Appendix 1 for an illustration of the PPEM framework.

Within the PPEM, projects, or interventions, may be either physical infrastructure projects or service developments applying to:

� Discrete sites

� Continuous routes

� Corridors

� Networks

As mentioned, in the interests of enhancing public transport services and infrastructure for the community, the PTA has indicated that it would share the PPEM with stakeholders seeking to determine the justification, value, and priority ranking of potential bus system (or other public transport) interventions.

For further discussion on other approaches to the justification of public transport priority initiatives, refer to Appendix 2.

Whilst other potential approaches exist for determining the justification for, and priority of, a range of public transport enhancement projects, it is recommended that the PPEM framework be used for this task in Western Australia.


4.2 Objectives & Performance Measures for Bus Priority

Whatever the technical details of the approach adopted to justify a public transport priority project, they should be evaluated with respect to transparent transport objectives and measurable performance criteria. For example:

Objective 1:

Increase the people-moving capacity of the existing and planned road system.

Performance Measures:

� Person-flows for bus & general lanes

� Vehicle occupancy levels for bus & general lanes

� Trip times and trip-time reliability for bus and general traffic lanes

� Vehicle average speeds and speed variability for bus & general lanes

Objective 2:

Increase the utilisation and efficiency of road-based public transport.

Performance Measures:

� Public transport person flows

� Public transport service frequency and vehicle utilisation efficiency

� Public transport trip times and trip-time reliability

� Public transport average vehicle speeds and speed variability

Objective 3:

Reduce vehicle emissions per person-trip (improve air quality).

Performance Measure:

� Relative change in emissions per person-trip

Objective 4:

Reduce use of non-renewable fuels per person trip (conserve non-renewable fuels).

Performance Measure:

� Relative change in fuel use / person-trip

4.3 Conclusions for the Assessment of Bus Priority Interventions

There is an extensive “pool” of interventions that may be used to provide priority for on-road public transport with the potential to employ different interventions in different combinations to address specific opportunities.

Bus priority measures should form elements within a comprehensive and integrated people (and goods) movement strategy. Furthermore, public transport priority interventions should be “assessed in the context of a set of strategies which have a time dimension ….”. (Jepson and Ferreira, 1999, op cit.)

Whilst it is useful to undertake “micro-analysis” that may focus on direct, measurable and localised, short-term objectives, such as bus travel time and operating cost savings, it is more difficult to quantify the potential contribution of bus priority measures to the achievement of broader, longer-term, social objectives. These objectives may include a shift to sustainable travel modes, improvements to the quality of human and physical environments, reduction of energy consumption, and so forth.

In addition, individual bus priority measures, introduced in isolation, may be significant in reinforcing a package of travel demand management interventions relating to parking supply and price, ride-sharing initiatives and a range of public transport investment and improvement measures.


5. Intelligent Transport Systems (ITS) for Bus Priority An increasingly significant component of the armoury to enhance bus service quality and to confer priority on public transport vehicles derives from developments in ITS.

In addition to the facilitation and provision of priority to bus services through supportive road infrastructure (design, construction and maintenance) the provision of traffic signal priority can result in significant travel time improvement for buses.

However, the greatest improvements in bus travel times (and perhaps the most effective means to achieve the magnitude of travel time improvements required to substantially influence mode choice) tend to result from integrated plans addressing road infrastructure, traffic signal priority, and parking restrictions over entire areas, or corridors.

Nevertheless, the provision of priority for public transport vehicles at signalised intersections may be a very beneficial intervention that provides assistance to the overall challenge of establishing substantial travel time improvements for on-road public transport.

The approach to traffic signal priority can be either passive or active, and can relate to isolated intersections or linked intersections within an urban traffic control (UTC) system. The major techniques for the provision of priority are as follows:

5.1 Passive Signal Priority Essentially, passive priority techniques vary the average settings for signalised intersections based on differences in “average behaviour” between vehicle categories, for example, buses and cars.

Passive traffic signal priority, therefore, seeks to accommodate the anticipated requirements of buses within the general traffic flow. Passive priority, within a linked traffic signal system, can be achieved relatively easily and at relatively low cost and assigns priority based on the weighting of buses relative to cars. (1 bus = 10 to 20 cars is the weighting generally used in Australia).

The most often applied passive priority techniques include:

5.1.1 Reduced Cycle Time Reducing the cycle time below that dictated by motor vehicle warrants can reduce the delay experienced by buses and reduce service schedule irregularities.

By reducing typical cycle times of, say, 60 seconds (depending on motor vehicle warrants), this technique may be particularly effective where buses are in their own lane and frequencies are high, and where buses need to cross a major street.

5.1.2 Priority Movement Repetition in Cycle

In this case, the movement required by buses would be introduced at more than one point in the signal cycle, thus reducing delays to buses. This technique may be particularly useful at multi-phase intersections and where buses are crossing a major road.


5.1.3 Green Priority Weighting This technique would allocate a prolonged green time for buses on a designated road (or lane) at the expense of increasing red time for the other road (or lane).

5.1.4 Phasing Design Phasing design may reduce bus travel times by introducing, eg. a right-turn phase to relieve congestion that is delaying buses, or by restricting a right-turn to reduce congestion caused by turning vehicles.

Figure 75: Signal Phasing Design for Bus-Only, Right-Turn Exemption at Wellington St., Perth

5.1.5 Signal Linking for Bus Progression

Average bus speeds may, in some road situations, be lower than general traffic. The selection of signal offsets (the staggered delay sequence between signals) in a linked signal network can be established to promote the progression of buses (where they are the slower vehicle category) provided there are no bus stops between linked signals that require buses to stop for passengers.

5.1.6 Diurnal Phasing Variation Traffic signal phasing may be varied by time-of-day to assist bus movements when they are at their peak. In this manner, priority can be assigned to the peak traffic flow direction, which improves traffic flow for all classes of vehicle, including buses and general traffic.

5.1.7 Synopsis Whilst the latest technology developments may be concentrated on automatic vehicle location (AVL), integrated traffic management strategies, bus operating systems, and active signal priority, the role of passive signal priority and other “passive” on-road priority treatments should not be discounted. They can form effective elements within a coordinated action plan for public transport priority.

5.2 Active Signal Priority Where buses operate in mixed traffic, it may be difficult to provide sufficient priority using passive techniques.

Better results are usually achieved with selective vehicle detection (SVD) to influence the operation of signals. The detection of a bus at a given point in the signal cycle can be employed to select an appropriate signal priority response. Techniques for providing active signal priority include:

5.2.1 Green Extension This technique is used to prolong the green phase and to enable a bus, once detected, to clear the intersection.

5.2.2 Green Early Start When a bus has been detected on approach to an intersection and is expected to clear the intersection prior to the normal onset of the signal green phase, the onset of the green phase can be accelerated to provide for passage of the priority vehicle.

5.2.3 Special Phase A special phase may be introduced that is not in the standard signal phase sequence. Following detection, a bus would employ this phase, which may be a bus-only phase, to undertake a movement that would otherwise be prevented. An alternative application of the special phase may be to clear obstructing traffic following detection of a bus, thereby creating the opportunity for passage of the priority vehicle.


5.2.4 Phase Suppression Phase suppression, or omission of a standard phase in the cycle, may occur when a bus priority phase is called. This promotes the allocation of priority to the bus.

5.2.5 Priority Phase Sequences In this case, a priority call may initiate a sequence of phases. For example, a special phase, or a phase extension, may be called to clear traffic from the bus path prior to the actuation of the bus priority phase itself.

5.2.6 Phase Compensation In providing active priority to a designated vehicle, there is often a temporary deterioration of conditions for other traffic streams. It may be desirable to provide active compensation, for example, phase extension, to other traffic following completion of the priority phase for buses.

5.2.7 Flexible Window Stretching This technique provides active priority for buses within a coordinated signal system, or at isolated sites. It is readily implemented within the SCAT traffic signal control system.

The technique identifies a period in the signal cycle within which the cross-street phases occur. The cross-street phases may be varied so that “Priority Green” can be provided to buses at any point in the signal cycle so that they would rarely encounter a red signal. In addition, the amount of unnecessary priority for buses is minimised under this approach.

5.2.8 Priority Green and B-Lights With this signalisation system, buses (and trams where they are used in other States of Australia) are given a head start at intersections; that is, buses get a green light before automobiles.

Because transit vehicles get a “jump” on automobiles queuing at a red light, they merge more easily back into traffic.

In Europe, where this system is common, “priority green” has been effective in reducing public transport travel times but has also had a

negligible effect on increasing private car travel times.

This approach to public transport priority is used successfully in Melbourne, Victoria. It is also used in the United Kingdom, where journey times for trams and buses have been reduced by this priority measure and the speeding up of service (by about 5 kilometres per hour, or 20% - 25%) sometimes means that fewer vehicles have to be deployed to deliver an equivalent transport task, saving resources for the public transport operator. (London Transport Buses Annual Report, 1996)

An enhancement of the “priority green” approach involves the installation of specific Bus-lights (B-lights) at some intersections.

All cities in Australia selectively employ “B-lights”. In Perth, B-lights have been successfully deployed at both approaches to the Causeway Bridge to provide for the advanced movement of buses relative to general traffic.

Figure 76: B-Lights at Eastern Approach to Causeway Bridge, Perth, Western Australia

White B-Light Symbol used in Western Australia

In Adelaide, South Australia, a number of traffic signals have "B" lights for buses.


These are activated through buses being detected in a bus lane on one of the approaches to an intersection.

A long detector loop is used, which is usually set back from the stop line. Signal controller programming provides for the signal sequence to be interrupted at one or more points in the cycle to allow buses to proceed with priority. A "B" light indicates that the bus can proceed through what is a red light for other traffic on the approach.

The advantages of the measure are reduced delays at intersections for buses and, therefore, better schedule adherence and reliability for public transport users. The main disadvantage is that there may be greater delays for other traffic.

"B" lights are usually provided in conjunction with a Bus Lane at an intersection, though this is not always the case. “B” lights are a successful priority measure for public transport. The key issues considered in opting for "B" lights are:

� Bus frequency

� Benefits from reduced bus delays

� Effect on delays for other traffic

A white B display legally permits a bus to move in any direction from the stop line of a bus-only lane. The move must be made with safety for the public and in accordance with any regulatory requirements.

A move in a specific direction (eg. a right- or left-turn) can be made under the control of an appropriate white arrow.

Bus lanterns (B-lights) are often used to control buses in bus-only lanes. A bus-only lane is legally and operationally different from a bus lane. The former is restricted to use by buses (and other eligible vehicles, eg. emergency vehicles) whilst the latter may be entered by general traffic for the purpose of making a legal turn into an intersecting street or a driveway.

Western Australian Requirements

In Western Australia, the WA Road Traffic Code 2000, Part 17 includes the following Regulations:

Regulation 247: Stopping for a Red B-light

Subject to regulation 249, the driver of a public bus approaching, or at, B-lights showing a red B-light shall stop:

(a) (if there is a stop line at or near the B-lights) as near as practicable to, but before reaching, the stop line; or

(b) (if there is no stop line at or near the B-lights) as near as practicable to, but before reaching, the nearest or only B lights.

Regulation 249: Exception to stopping for a red or yellow B light

“…. the driver of a public bus approaching or at B lights showing a red or yellow B light does not have to stop if the traffic-control signal is also showing a white arrow, and the driver is turning in the direction indicated by the arrow.

Regulation 250: Proceeding after Stopping for a Red or Yellow B-light

The driver of a public bus who stops for B-lights showing a red or yellow B-light shall not proceed until:

(a) a white B-light is showing; or

(b) no B-light is showing and traffic-control signals at or near the B-lights are showing a circular green light.

Regulation 251: Proceeding when a Traffic-Control Signal Shows a Circular Red Light and a White B-light or White Traffic Arrow is Showing

(1) The driver of a public bus approaching or at a white B-light at or near traffic-control signals showing a circular red light may proceed straight ahead, or turn, despite the circular red light.

(2) The driver of a public bus approaching or at a traffic-control signal showing both a white arrow and a circular red light may turn in the direction indicated by the arrow, despite the circular red light.


5.3 Issues in Evaluating Active Priority

Numerous theoretical and empirical evaluations of active signal priority have been undertaken throughout the world, indicating varying ranges of, but generally modest, travel time savings for buses as a result of active signal priority.

The increasing sophistication of active bus priority technologies also involves real-time communications between buses, passenger information systems, ticketing systems and UTC systems. This architecture permits the increasingly subtle manipulation of traffic signal phasing to enhance bus progression whilst minimising adverse impacts on other traffic. As a consequence, it has been suggested that the “centrally controlled integration of real-time passenger information, bus timetables, real-time bus progress, general traffic conditions and variable message signs has potential to significantly improve arterial road operations (so that) priority may be given to buses based on their current operational and passenger occupancy status.” (Jepson and Ferreira, 1999, op cit.)

However, it should be recognised that, notwithstanding the evolving sophistication of active signal priority based on SVD – and, increasingly, on AVL – simple, common sense interventions like exemptions from turn restrictions for buses, and the use of bus pre-signals to advance buses at congested and constricted sites, can offer very significant advantages for buses.

Reference should be made to the Public Transport Authority’s companion publication “Design & Planning Guidelines for Public Transport Infrastructure: Traffic Management & Control Devices” for further information about road and traffic management techniques to improve public transport performance.

In this regard, it is important to adopt a broad view and acknowledge the individual components of overall bus journey time so that integrated enhancement strategies can be developed to maximise travel time savings and improve travel time reliability by

harnessing the most appropriate priority measures from a palette of options available.

5.4 Generic Techniques to Assign Priority

5.4.1 Selective Vehicle Detection (SVD)

Historically, selective bus detection has been achieved in several ways through use of in-road inductive loop technologies:

Long Loops

Two adjacent inductive loops are coupled by logic that detects the presence of a long vehicle – not necessarily a bus.

Single Large Loop

A single, large loop is set to respond only to a long vehicle.

Vehicle Profile Detection

The signal from a conventional inductive loop is interpreted by a microprocessor relative to the characteristic inductive profile for a bus.

Figure 77: Typical Layout of SVD and Signal Priority

(Source: PPK & McCormick Ranking Cagney, 2001)

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Advances have been achieved in SVD in recent years resulting in three main families of vehicle detection methods applying:

Point Detection Systems

Vehicles are equipped with “electronic registration plates” or “tags”, which send a message including the vehicle identification to a specialised loop detector able to read this message when the vehicle crosses it. In this case, there is a precise location of a bus at a given time.

Area Detection Systems

An infrared, radar or radio frequency emitter is mounted on the vehicle, and a beacon receives the messages when the vehicle occupies the area covered by this beacon. Messages can include complementary information such as bus stop departure time, ahead/behind of schedule signal, and turning signal.

The quality of signal reception quality may depend upon meteorological conditions.

Integrated Priority Systems

In this case, public transport management is entrusted to an Automated Vehicle Monitoring (AVM) system that collects all bus positions and communicates with a Traffic Control Centre in order to manage the signal priority actions.

These systems also use Automatic Vehicle Location (AVL) systems with different possible localisation techniques. Usually public transport vehicles either use on-board positioning systems (odometry, GPS, GLONASS), which enable them to send their position either in a quasi-continuous way (eg. every 20 seconds) to the public transport control centre, or only when they pass predetermined locations.

Localisation beacons placed along the route enable the drift of odometry-based localisation systems to be compensated.

It should be acknowledged that, where a public transport route crosses a coordinated traffic signal system, the effect of priority measures for public transport may adversely impact on signal linking and system recovery

time for the non-priority direction in circumstances where the intersection is near saturation.

5.4.2 Automatic Vehicle Location (AVL) There are three major types of automatic vehicle location (AVL) systems:

Beacon-Based Systems

Beacon-based bus detection utilises in-road detector loops to identify buses “tagged” with a signal-emitting transponder. It is the most common form of AVL and is relatively reliable.

Research by Hounsell & Landles (1995) in the United Kingdom, suggests that the optimum location for the loop detector is 70 – 100 metres in advance of an intersection. (Hounsell & Landles, 1995.)

Satellite Global Positioning Systems (GPS)

Satellite GPS is capable of continuously tracking the location of a bus. It does not require that a bus be selectively identified by travelling through a specific detection zone. GPS technology is relatively expensive, but advances in the technology are bringing GPS within reach for many bus systems.

Land-Based Radio Beacon Systems

This system involves deployment of microwave equipment on buses to allow the detection of buses by roadside readers. Information is then relayed to the UTC centre to facilitate traffic signal priority for buses.

Figure 79: Example of an AVL Configuration with a Low Degree of Coupling

(Source: Houston Metro)


5.5 Australasian Intelligent Transport Systems (ITS) Bus Priority Examples

5.5.1 SCATS Operations in WA In Western Australia, SCATS (Sydney Coordinated Adaptive Traffic System) is used to control 743 signalised intersections

SCATS is a proprietary system developed and distributed by the Roads & Traffic Authority (RTA) of NSW.

The following characteristics apply to the operation of SCATS in Western Australia:

� As at October 2003, all 743 permanent traffic signal installations in WA were connected to SCATS. (The 40 country signalised sites are presently connected through the SCATS dial-up system rather than the permanent connection mode used for sites in the Perth metropolitan area.)

� Although all sites are monitored, not all sites are coordinated. The number of traffic signal sites that are coordinated varies according to traffic volume and flow, and time of day, from approximately 350 sites during peak periods to less than 20 sites during the middle of the night.

� Main Roads WA operates SCATS Version 6.3.0.0 using 9 regional computers that communicate with a SCATS Central Manager using a Local Area Network (LAN) architecture.

� Therefore, the Main Roads WA SCATS architecture and operating version are fully PTIPS - and RAPID-compatible. (Refer to Sections 5.5.3 & 5.5.4 for discussion of PTIPS and RAPID, respectively.)

� Main Roads WA has conducted an initial trial of RAPID; however, neither RAPID nor PTIPS are currently operating in WA.

� Within PTIPS, the Main Roads WA SCATS function is fully configurable with respect to the type of priority that can be afforded to buses.

� Prospects exist for a trial of PTIPS in Perth; however, additional pilot project development will be required to determine

the level of priority that will be provided to buses, the detection methodology that will be used, and the method of implementation of PTIPS that would be appropriate in Perth.

5.5.2 SCATS Operations for Melbourne Tram Priority

Introduction

The Melbourne SCATS approach is an example of both passive and active public transport priority in a centralised Urban Traffic Control (UTC) system.

In Melbourne, SCATS controls 250 kilometres of tram tracks and 180 sets of signals. SCATS adjusts signal plans based on traffic conditions at critical intersections. These critical intersections control coordination within sub-systems and sub-systems coordinate with other sub-systems as traffic demands vary. Sub-systems can include from one to ten intersections.

Control Strategy Description

On detection of a tram approaching a junction, priority phases can be called to either clear the queue ahead of the tram or to provide a phase extension. Flexibility is provided allowing priority to be given or not depending on the time of day, tidal flow determination based on traffic flows or on how congested the intersection is.

Detection Methods

The trams are detected using two selective tram detectors on each approach. One detector loop is placed approximately 200m from the stopline; the other is at the stopline.

Benefits

A evaluation of Melbourne SCATS operation on a small network of two parallel main routes and three crossing routes showed (in peak conditions) travel-time savings to trams of between 6% and 10%, with benefits to private cars between 1% and 7%. On the crossing routes, results for private vehicles varied between 41% travel-time saving and 13% travel-time disbenefit, depending on signal coordination and tram priority circumstances.


There are further developments relating to bus priority at signalised intersections using selective vehicle detection (SVD) in several major Australian cities. These include:

5.5.3 Public Transport Information & Priority System (PTIPS), Sydney

The Roads and Traffic Authority (RTA) of NSW has developed a Public Transport Information and Priority System (PTIPS) as a basis for the enhancement of bus travel times. The development of PTIPS will also provide public transport fleet operators with information about the status/location of vehicles and will provide public transport passengers with real-time information about services.

Architecture & Operation of PTIPS

PTIPS has been developed to:

� Track public transport vehicles

� Predict arrival times of public transport vehicles at intersections and bus stops

� Generate traffic signal priority requests for public transport vehicles

� Provide user information for operators of public transport fleets

� Provide real-time passenger information for users of public transport

To achieve this, it should be emphasised that traffic signal priority for buses requires, at least, SCATS version 6.0, or a more recent version. This requirement exists because the SCATS ITS interface, through which priority requests are passed from PTIPS to SCATS, is only available on later versions of SCATS.

PTIPS tracks public transport vehicles by:

� Locating public transport vehicles using a suitable positioning system, for example, GPS-based, odometer-based or beacon-based AVL systems are feasible.

� Using spatial descriptions of public transport service routes to determine the relative locations of vehicles with respect to their route.

This capability allows PTIPS to be functionally independent of the nature of the

AVL systems that may be used by various public transport fleet operators.

For the prediction of vehicle travel times, PTIPS uses:

� Relative location of the vehicle.

� Estimates of route link travel speeds.

� Status of the traffic signals at the next few intersections along the vehicle’s route (obtained from SCATS).

� Traffic information in the vicinity of where the vehicle is located (obtained from SCATS).

PTIPS generate priority requests for public transport vehicles in the following manner:

� Determining the arrival time of the vehicle at the next intersection(s).

� Generating requests for “green windows” at these intersections.

� Specifying the required “green window” – the phase type (phase extension or early recall), start-time, and duration that best supports the vehicle movement.1

� Resolving conflicts between different priority requests.

Further system developments to access public transport operator timetables will provide the capability to determine whether a vehicle is late or early and the amount of this deviation from the schedule. This information could be used to selectively prioritise the vehicles at signalised intersections and to feed real-time passenger information attributes of PTIPS.

The major users of the PTIPS are:

1 – PTIPS Administrators

� Start up and shut down PTIPS

� Enable/disable priority requests

� Configure PTIPS and its connections

� Monitor the operation of PTIPS

� Configure other users’ profiles

1 Where possible, an extension of a phase is preferred, as it is less disruptive to the operation of the signals.


2 – Public Transport Operators

� Track individual public transport vehicles

� Track public transport route services

� Edit the spatial details of the routes

� Analyse fleet service performance

3 – SCATS Users

� Monitor the interaction between SCATS and PTIPS

� Disable, or enable, PTIPS connections based on traffic conditions

(Jarjees, NSW RTA, personal communication, June 2003)

Trials of PTIPS

Trials of PTIPS on the Sydney Airport Express Bus Service in 2001 were undertaken with PTIPS using a GPS-based bus location and priority platform.

Buses were equipped with a Global Positioning System (GPS) receiver and a GSM (Global System for Mobile telecommunications) modem, including a Vehicle Tracking System (VTS) software package that displayed the locations of tracked vehicles on a map to an accuracy of 10 metres.

The trials indicated that PTIPS reduced both mean travel times (up to 21%) and variability of travel times (up to 49%) for buses. (Mehaffey & Jarjees, 2001)

Figure 80: Improvements in Bus Travel Times on Trial Route Sections due to PTIPS

050

100150200250300350400450

MeanTravelTime

(seconds)

293-346 346-293 681-2526 2526-681

Sub-Section

Mean Sub-Section TravelTi

No-priorityPriority

-0.8%-0.8%

21.3%21.3%

12.8%12.8%20.7%20.7%

(Source: Traffic Systems Branch, NSW RTA)

Figure 81: Improvements in Bus Travel Times on Trial Route Sections due to PTIPS

0102030405060708090

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293-346 346-293 681-2526 2526-681

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No-priorityPriority

48.7%48.7%

33.2%33.2%

43.0%43.0%

28.1%28.1%

(Source: Traffic Systems Branch, NSW RTA)

Refer to Appendix 3 for further details regarding PTIPS and to Appendix 4 for an illustration of the PTIPS Environment.

5.5.4 BLISS / RAPID – Brisbane

Introduction

In Brisbane, BLISS (Brisbane Linked Intersection Signal System) is used to coordinate traffic flows on specific parts of the Brisbane road network.

BLISS is a PC-based UTC system. The road network is divided into regions, each under the control of a single PC. Each PC can coordinate up to 63 sets of traffic signals. A system master (also a PC) providing effective control over all the signals within a city supervises the whole system.

Brisbane currently has 650 signalised intersections under the control of a single system master PC and 11 regional master PCs.

Brisbane City Council has developed an active bus priority system known as RAPID, which operates within the BLISS Urban Traffic Control system. (Campbell & Moriandi, 1997)

As well as being capable of providing priority to buses, RAPID can also give priority to emergency vehicles.


Figure 82: Bus Lane Priority, Brisbane

Development & Functionality of RAPID

The RAPID bus priority system initially provided public transport priority at 14 signalised intersections in a trial on Waterworks Road, Brisbane commencing in November 1996. The trial was successful and led to the system being extended. The RAPID system is also operating in Auckland, New Zealand.

The BLISS local coordination module forms the basis of the RAPID bus priority and passenger information system. The RAPID system operates independently of the traffic control system. However much of the same infrastructure is used. Therefore, whilst RAPID is highly integrated into the BLISS system in Brisbane, it can also run alongside an alternative traffic system where BLISS is not used for traffic control.

Selective priority for buses occurs within the architecture of the traffic signal coordination system based on the application of several decision criteria:

� Current schedule-adherence of the bus

� Number of passengers

� Current status of signal phasing

� Other current demands on the Urban Traffic Control (UTC) system

These criteria are then assessed using algorithms that allocate conditional priority to buses, ie. priority conditional upon the satisfaction of programmed requirements for the UTC system.

Bus Priority Interventions

The permitted interventions to promote bus priority at intersections include:

� Starting a phase early

� Extending a phase

� Not skipping a phase because a bus is known to be approaching

The priority phase is cancelled if the bus is detected at the stop line and it has a green signal, or if the bus is detected further downstream, or after a time-out period has elapsed.

If a phase is extended in the current signal cycle, then it is shortened in the next cycle by the same duration. All interventions are recorded and stored in a database.

If there is a priority conflict at an intersection, a decision has to be made about which vehicle gets priority. For buses, a priority level based on the number of passengers on the bus and the level of lateness determines this. Normally the bus with the most recorded passenger boardings gets the priority.

Existing Detection System

A vehicle identification tag (known as a VID tag) is fitted to the underside of each bus. When the bus drives over a loop in the road, the tag transmits a message, via the loop, to be decoded by the VID receiver in the traffic signal controller cabinet. The message is then relayed to the BLISS system using existing communications infrastructure.

Each tag on the bus is interfaced to its electronic ticketing machine (ETM). The message transmitted by the tag consists of a static component and a dynamic component. The dynamic component is provided by the ETM and consists of the bus service number, the scheduled start-time, and the passenger loading. The static component identifies the bus operator (company) and the bus number.

GPS Hardware

For RAPID, the tracking of buses, using GPS-based technology, is supported by a digital odometer to offer real-time tracking. This allows the buses to monitor their own position


to within a few metres, even in urban “canyons” and tunnels. Operators can see the disposition of their fleet and can select individual vehicles for more detailed tracking.

In duress situations the bus can be continuously monitored and traffic control staff alerted to minimise response times.

RAPID to SCATS Interface

As is the case with PTIPS, the RAPID public transport priority system requires SCATS version 6.3.0, or later versions.

Passenger Information

Algorithms within RAPID combine historic travel data with current travel times to predict bus arrival times for the passenger information system. Real-time (AVL-based) positions of buses are applied to provide information for passengers at bus stops.

“Next stop” displays keep on-board passengers informed about bus progress.

Figure 83: Real-Time Passenger Information System, SouthEast Busway, Queensland

Figure 84: Real-Time Passenger Information at

Bus Stop, Brisbane.

(Refer to Appendix 5 for an illustration of the system architecture for RAPID.)

5.6 International ITS Bus Priority Applications

The United Kingdom has extensive experience in the development and implementation of bus priority programs. Evaluation of bus priority has identified some potentially significant improvements in travel time.

The following figure provides examples of travel time reductions (in minutes) achieved with bus priority on a 10-kilometre journey on five routes surveyed in the UK.

Figure 85: Examples of Bus Travel Time Reductions for Trials of Bus Priority, UK


(Source: The Department of the Environment, Transport & the Regions, UK, Traffic Advisory

Leaflet 06/01: Bus Priority)

To identify and compare a range of vehicle priority schemes, the UK Department of Environment, Transport and the Regions (DETR) sponsored the project UTMC-01: Selected Vehicle Priority in the Urban Environment (SPRUCE) to determine the state of the art in selective vehicle priority. http://www.its.leeds.ac.uk/projects/spruce/

The project considered developments across the full range of applications for selective vehicle priority within urban traffic signal networks, including bus priority and Light Rail Transit (LRT) priority.

For further discussion of selected, international ITS bus priority applications, refer to Appendix 6.


6. Bibliography

Bly, P.H., Webster, F.V., & Olfield, R.H., “Justification for Bus Lanes in Urban Areas”, Traffic Engineering & Control, February, 1978

BSD Consultants, High Occupancy Vehicle and Bus Priority Framework: Stage 1, Final Report, November 1996, for Transport WA

Campbell, J & Miorandi, J, “Waterworks Road Bus Priority Pilot”, Proceedings of the 3rd International Conference of ITS Australia, Brisbane, March 1997.

Cranshaw, V. and Shaw, M.J. (1995) “Vehicle Detection in Norwich”, Highways & Transportation, October 1995.

Cundill, M.A. & Watt, P.F., “Bus Boarding and Alighting Times”, Transport & Road Research Laboratory, Report No 521, 1973

Department for Planning & Infrastructure, Western Australia, “ Metropolitan Transport Strategy, 1995”.

Department for Planning & Infrastructure, Western Australia, “Better Public Transport: Ten-Year Plan for Transperth 1998-2007”.

Department of the Environment, Transport and the Regions (DETR), United Kingdom “Keeping Buses Moving”, Local Transport Note 1/97, 1997

Gardner, K. “Quality Bus Corridors: Initiatives To Attract Passengers”, UITP Conference on Innovation in Road Public Transport, Maastrict, 8th February 2001

Henry J.J. and Farges, J.L. (1994) “PT Priority and PRODYN”, in Proceedings of the First World Congress on Applications of Transport Telematics and Intelligent Vehicle-Highway Systems, Paris, Nov/Dec. 1994.

Hounsell, N.B. & Landles, J.R., “Public Transport Priority at Traffic Signals in London: Progress and Opportunities”, 2nd World Conference on Intelligent Transport Systems, Vol. 1, 1995, Yokohama

Jepson, D. & Ferreira, L, “Enhancing Bus Operations on Arterial Roads: Some Lessons from an Australian Case Study”, 1998.

Jepson, D & Ferreira, L “Assessing Travel Time Impacts of Measures to Enhance Bus Operations – Part 1: Past evidence reviewed”, Vol 8 No 4 1999 Road & Transport Research

London Transport Buses Annual Report, 1996

Mauro, V. and Di Taranto, C. (1989), "UTOPIA", CCCT'89, AFCET Proceedings, September 1989, Paris, France.

Mehaffey, A, Jarjees, G & Berghold, L, “A Public Transport Information and Priority System – PTIPS: An Overview”, Proceedings of the 8th World Congress on Intelligent Transport Systems. Sydney, Australia. 30 September – 4 October 2001.

Mehaffey, A. and Jarjees, G. “Preliminary Trial Results of the Public Transport Information and Priority System (PTIPS)”, Proceedings of the 8th World Congress on Intelligent Transport Systems. Sydney, Australia. 30 September – 4 October 2001.

Nuwursoo, C.K. & May, A.D., “A Technical Memorandum for Planning HOV Lanes on Freeway”, Working Paper No. UCB-ITS-WP-88-3, University of California, Berkeley, 1988

Olfield, R.H., Bly, P.H. & Webster, F.V. “With-Flow Bus Lanes: Economic Justification Using a Theoretical Model”, Transport Road Research Laboratory, Report No. 809, 1977

Panter, David “RAPID Bus Priority Discussion”, Saab ITS Pty Ltd, 2002.

PPK and McCormick Rankin Cagney “Brisbane High Occupancy Vehicle Arterial Roads Study” Final Report for Queensland Main Roads, Queensland Transport and Brisbane City Council, January 2001.

Ritchie, S.G., “Arterial Bus Lane Warrants”, Civil Engineering Working Paper 78/9, Monash University, September 1978

Sinclair Knight Merz, “Right-Turn Bus Acceleration Lanes at T-Junctions”, July 2002, for Department for Planning & Infrastructure.

Taylor, M.A.P., “Planning and Design for On-Road Public Transport” in Traffic Engineering & Management, edited by Ogden, K.W. & Taylor, S.Y., Monash University, 1996


Texas Transportation Institute. TCRP Report 19, “Guidelines for the Location and Design of Bus Stops.” TRB, National Research Council, Washington, DC, April 1996

Transport Research Board, Highway Capacity Manual, Special Report 209, 3rd Ed., 1994

Vuchic, V.R., “Urban Public Transportation: Systems and Technology” Prentice Hall, Englewood Cliffs, N.J., 1981.

Western Australian Road Traffic Code 2000, Part 17.


Appendix 1: PPEM Framework

Figure 86: Framework for the Project Prioritisation & Evaluation Model (PPEM) PTA

DEFINE OBJECTIVES ANDLIMITS OF EVALUATION

(PROJECT)

BCA EvaluationQuantifiable

Confirm EvaluationParameters

(PARAMETERS)

Define Base CaseOption

Define ProjectOptions

Capital Costinc. Design((INPUT –

COSTS)

Operating costseach year(INPUT –

OPCOSTS)

Communitybenefits

(INPUT –BENEFITS)

Maintenancecosts each year

(INPUT –COSTS)

For the Base Case and each of the Project Options provide…

Passengers

Journey Time

DiscountedCommunity Benefits,

base + options

DiscountedLifecycle Costs,base + options

Value of Time

Benefit Cost Ratio(BCR)

Externalities

Air QualityNoise

VibrationWater QualitySpecial AreasVisual Impact

Community SeverancePsychological distressCommunity PoliticsLocal Government

Other(EXTERNALITIES)

Non Quantifiable

Key(BCR) – Model worksheetand manual section heading


Appendix 2: Case Studies of Approaches to Justifying Bus Priority Case Study 1: Potential HOV & Bus Priority Framework (DPI, 1996) In 1996, the DPI examined a decision framework for the assessment and justification of HOV priority projects, including bus priority. (BSD, 1996)

Decision criteria are required to promote sound judgements about prospective HOV schemes, including bus priority schemes. These criteria may include the following:

� Traffic volumes

� Road system level-of-service

� Traffic speeds

� Bus and bus passenger numbers

� Number of traffic lanes

� Congestion on parallel road routes

� Travel time, reliability, cost, and convenience improvements

� Peak bus lane demand

� Impacts on general traffic lanes

� Benefit - cost ratio

A comprehensive decision framework for justifying and planning a bus priority project may include the following stages within a systematic decision hierarchy:

Stage 1 Statement of Objectives

Stage 2 Strategic Planning Stage

Stage 3 Programming Stage

Stage 4 Delivery Stage

Stage 5 Monitoring Stage

Stage 6 Modification / Improvement Stage

With respect to indicative values assigned to prospective project justification criteria, research indicated that the following values might be appropriate:

Decision Criterion

Indicative Threshold Value

Traffic Volumes � Freeway: min. 1500 veh. / lane in peak hour

� Arterial: min. 1000 veh / lane in peak hour

Road Level-of-Service

� Level-of-Service “D”, or worse (1)

Traffic Speeds � Freeway: average less than 50 km/h in peak hour

� Arterial: average less than 40 km/h in peak hour

Number of Buses

� 45 buses per peak hour (lane take) (2)

� 20 buses per peak hour (lane addition) (3)

Number of Bus Passengers

� 2,250 passengers / peak hour (lane take) (2)

� 1,125 passengers / peak hour (lane addition) (3)

Number of Traffic Lanes

� Generally 3 in each direction

Travel Time Savings

� Minimum of 8 -10 minutes

General Traffic Lanes

� No significant loss of service

(1) Austroads Level of Service “D” is defined as a situation of unstable flow. All drivers are severely restricted in the selection of their desired speed and in being able to manoeuvre within the traffic stream.

(2) In seeking to justify the introduction of a Bus Lane, the “lane take” threshold approximates the bus and passenger levels at which it may be reasonable to take a lane from general traffic to dedicate to Bus Lane operations. Notwithstanding this threshold being satisfied, it may be regarded as “politically” inappropriate, to remove a traffic lane from general use despite the benefits to public transport.

(3) The “lane addition” threshold does not imply that, at this (lower) level of bus and passenger throughput, it would be justifiable to construct a new, dedicated Bus Lane. Rather, the threshold is likely to relate to a situation where roadway widening is already planned, or where the introduction of kerbside parking restrictions makes a lane available as a Bus Lane. In such a case, the introduction of bus priority may be justifiable at a lower level of bus throughput than would be required if bus priority were introduced in a manner that would displace existing traffic from a traffic lane.

However, where a lane is being added to a roadway, or kerbside parking prohibited to assist traffic flow, a threshold of 20 buses and 1,125 passengers in the peak hour is unlikely to be sufficient to justify exclusive restriction of the lane to buses. At relatively low levels of bus demand, joint usage of a dedicated lane by buses and HOV cars may be acceptable.


Case Study 2: Synopsis of Research into Warrants for Bus Lanes A considerable amount of research has been undertaken over several decades to determine appropriate justifications and warrants for the introduction of bus lanes and other bus priority facilities.

Olfield et. al. (1977) suggested that, in the United Kingdom, a bus flow of more than 120 buses per hour may be required to justify a bus lane with no set-back at a signalised intersection.

With respect to travel timesavings for buses in bus lanes, it has been suggested that significant benefits arise where traffic saturation levels exceed 90%. However, it is also recognised that bus lanes may be justified at lower saturation levels. (Bly, Webster & Olfield, 1978)

For the American context, the Transportation Research Board (1994) has indicated that bus lanes would be warranted at minimum, one-way bus volumes of 30 – 40 buses per peak-hour and with passenger volumes of approximately 1200 passengers per peak-hour.

A further perspective has been offered by Vuchic (1981) who proposed that bus lanes would be warranted where they carry as many people as the remaining general traffic lanes.

This proposal is likely to be a conservative approach to bus lane provision, as it makes no acknowledgment of social, environmental and strategic transport objectives.

However, the application of such a criterion produces the following warrant:

Bus flow rate = q r / (N – 1), where:

q = flow rate of general traffic N = total number of lanes r = ratio of mean car and bus occupancy

With respect to bus lane justification warrants, Jepson & Ferreira (1999) note from comparative research, that bus lane justification warrants show a range of values “without (defining) a single overall bus flow rate which can be used universally.”

Moreover, it could be argued that, for Australian conditions, and in the context of strategic transport planning objectives to achieve longer-term mode-shifts favouring public transport, the justification for bus lane interventions may be established at lower bus flow levels than may be reflected in warrants derived in the United Kingdom or the USA. Therefore, whilst the determination of bus lane warrants appropriate for Australian conditions may assist planners in identifying opportunities to enhance public transport service, warrants should be used only as a broad guide for possible bus priority interventions, not as a rigid pre-requisite.

Case Study 3: Other Bus Warrants & Decision Frameworks Richie (1979) identified a range of arterial bus lane warrants and in so doing, provided some valuable insights into the use of warrants as justification criteria for bus lanes.

In this respect, whilst many bus lanes have been successful in improving bus travel times, the cost-effectiveness of isolated schemes, measured in terms of passenger time and vehicle cost-savings, has often been quite modest. However, integrated schemes, deployed throughout a corridor, can offer significantly enhanced benefits. Furthermore, planning for bus priority interventions should embrace social and environmental objectives.

The bus flow warrants derived by Ritchie were based on the following assumptions:

� The priority deployment was an exclusive, with-flow bus lane on an arterial road link between two successive signalised intersections

� Benefits were assessed only in terms of savings in passenger travel times and vehicle operating costs

� Operation of the down-stream signals was fixed-time with standard cycle length of 86 seconds

� Turning traffic was assumed not to affect intersection capacity


Min. Hourly Bus Flow for Bus Lane on 2-Lane Approach with Optimum Set-Back of Bus Lane

Intersection Degree of Saturation

Proportion of green

time

Bus Passenger Occupancy

60 50 40 30 20

0.7

0.3 62 68 74 82 92 0.4 63 69 77 86 98 0.5 63 70 78 88 102

0.8

0.3 49 54 60 67 77 0.4 59 65 72 82 94 0.5 68 76 84 96 111

0.9

0.3 25 28 32 37 44 0.4 49 55 62 71 83 0.5 69 76 85 97 113

0.95

0.3 10 12 13 16 19 0.4 20 23 26 31 37 0.5 40 45 51 59 71

0.97

0.3 5 6 7 8 10 0.4 5 6 7 8 10 0.5 15 17 20 24 29

Min. Hourly Bus Flow for Bus Lane on 3-Lane Approach with Optimum Set-Back of Bus Lane

Intersection Degree of Saturation

Proportion of green

time

Bus Passenger Occupancy

60 50 40 30 20

0.7

0.3 54 59 67 76 88 0.4 54 60 68 78 92 0.5 54 61 69 80 94

0.8

0.3 44 50 56 64 76 0.4 50 55 63 73 86 0.5 59 66 75 87 104

0.9

0.3 30 34 39 45 54 0.4 45 50 57 67 80 0.5 59 67 76 88 105

0.95

0.3 15 17 20 24 29 0.4 30 34 39 46 55 0.5 45 51 58 68 82

0.97

0.3 5 6 7 8 10 0.4 15 17 20 24 29 0.5 25 29 33 39 48

Whilst the foregoing tables of warrants were developed as a guide for planning bus lanes, it was acknowledged that “it may not be desirable to use a set of warrants based only on economic considerations because other non-quantifiable aspects may make bus priority worthwhile. All situations are different and warrants cannot be equally applicable to all cases.” (Ritchie, op. cit. p9)

This leads to the position that satisfaction of a warrant is not, in itself, sufficient justification for the implementation of a bus priority measure and, conversely, the non-satisfaction of a warrant is not, in itself, justification for not implementing a bus priority measure.

It should also be acknowledged that the application of bus flow warrants like those listed above does not provide an authoritative basis for considering whole-of-corridor justification (because such warrants are focused on individual road links) or for incorporating broader social, environmental, and strategic transport system objectives. Bus priority interventions should be evaluated in the context of a range of transport and non-transport options that seek to manage travel demand and optimise the efficiency and effectiveness of transport system services and infrastructure.

Case Study 4: Justifying Bus Priority in Oregon, USA A further example of criteria used to evaluate bus priority schemes (and other HOV schemes) is the approach taken in Oregon, USA.

www.hov.odot.state.or.us

The assessment and justification criteria used in Oregon include:

� Total Person Throughput. This is a measure of how many people move past a point in a given period of time. Traditionally transport agencies measure only the number of vehicles, but on HOV lanes they measure the number of vehicles, number of people per vehicle, and the number of people using transit. Increased person throughput and higher average vehicle occupancy are goals.

� Travel Times. Transport agencies measure travel time to determine how long it takes HOVs, SOVs and freight vehicles to travel on roads with HOV lanes. No net increase in travel times during the afternoon rush hour is a goal.

� Safety. Agencies measure the accident and incident rates on sections of highway before and after HOV lanes are established. No increase in incident and crash rates is a goal.


� Enforcement. This is a qualitative measure of how enforceable a HOV lane is. Agencies will track the number of tickets issued, the HOV lane violation rate, and observations of police enforcing the lane. Minimal violation rate and maximum perception that users obey HOV rules is a goal.

� Beginning and Ending Transitions. The beginning and ending of an HOV lane can create weaving movements or other traffic flow problems. Agencies monitor the traffic operations to evaluate how HOV lanes affect traffic flow.

� Traffic Diversion. Excessive delays in general purpose lanes may cause traffic to divert to parallel routes. Traffic counts are taken before and after HOV lanes are established to determine if significant traffic is diverted. The goal is to minimise traffic diversion.

� HOV Lane Utilisation. This is a measure of how many vehicles are using the HOV Lane in a given time period relative to the maximum capacity of the lane.

� Transit Ridership. Agencies track how many people ride transit during peak periods when the HOV lane is in service.

� Increase in Transit Service. Agencies measure the increase in transit service and compare it to the increase in transit ridership. This permits an understanding of the increase in transit ridership due to the HOV project compared to normal increases in ridership that result from an increase in transit service without an HOV facility.

� Number of People Per Vehicle. Agencies observe traffic to determine the number of people per vehicle during peak periods.

� Park & Ride Use, Van Pools & Employer Programs. Agencies track the use of the Park & Ride and vanpools.

� Public Perception. Agencies survey commuters and compare responses before and after HOV lanes are established.

Case Study 5: Gold Coast Hwy. Assessment of Bus PriorityJepson & Ferreira (1998) have undertaken an evaluation of a range of bus priority treatments and criteria for justification based on a case study of the Gold Coast Highway, Queensland.

Potential bus travel timesavings of up to 20% were identified from an approach that established initial “person throughput” objectives as the basis for optimising investment in the 4-lane highway.

A methodology, using the following equation, was developed for various combinations of traffic conditions (traffic flows, signal settings, vehicle occupancies, and road layouts) to determine the minimum number of passengers required to justify possible bus priority measures (bus lanes, signal priority, transit lanes, busways, ticketing systems, bus stop siting, and passenger information systems): Min(bus) = (dcar1*Vcar*OCCcar) – (dcar2*Vcar*OCCcar)

__________________________________ Vbus * (dbus2 – dbus1)

Where: Min(bus) = min. bus pax. to justify bus priority dcar1 = av. delay to cars if no bus priority Vcar = volume of cars (excluding buses) OCCcar = av. occupancy of cars dbus1 = av. delay to buses if no bus priority Vbus = volume of buses OCCbus = av. number of pax. in buses dbus2 = av. delay to buses with bus priority dcar2 = av. delay to cars with bus priority

It is suggested that the formula provide “rule-of-thumb” guidance for the selection of priority interventions for a 4-lane arterial road with signalised intersections at 250-m. spacing.

Given the possible variance in the number of lanes on a given arterial roadway (including turning lanes at intersections) and signal spacings at other than 250 metres, the “rule-of-thumb” caveat should be emphasised when applying the approach more generally.

However, some flexibility is offered as the parameters used can be:

� Existing traffic volumes / bus occupancy � Forecast traffic volumes / bus occupancy � Target traffic volumes / bus occupancy


Appendix 3: Public Transport Information & Priority System (PTIPS) The PTIPS initiative combines several systems that operate in conjunction with PTIPS to provide real-time passenger information and on-road public transport priority. These systems comprise the PTIPS environment.

The PTIPS Environment The AVL Bridge Public transport operators may use different types of AVL (Automatic Vehicle Location) systems. Therefore, PTIPS is separated from different AVL systems by an AVL Bridge, which provides vehicle positioning information in a standard format via a standard channel – a Transmission Control Protocol/Internet Protocol (TCP/IP) port.

Spatial Database The Spatial Database contains information that describes each public transport route, divided into individual link paths between consecutive intersections.

The database also specifies the movement of public transport vehicles on routes, the location of bus stops.

SCATS Priority Extender (SPE) This application operates in the background and accesses SCATS information in the SCATS central Manager, through the SCATS ITS Interface.

The SPE also contains state of all intersections on the public transport routes. The SPE functions by receiving, and responding to, a PTIPS request for the traffic signal phase status of an intersection. (In future, the SPE could also receive and pass on information about the traffic conditions in the vicinity of designated intersections.

PTIPS Data Agent This is a CORBA- (Common Object Request Broker Architecture) based server application that maintains public transport system entities,

such as companies, services, vehicles. PTIPS updates the status of these objects based, for example, upon the receipt of a new AVL message from a public transport vehicle.

PTIPS GUI (Graphical User Interface) Three types of PTIPS users have been identified:

� The PTIPS Administrator (starts, closes and operates PTIPS)

� The transit user, usually the representative of a public transport operator

� The SCATS user, who monitors the interaction between SCATS and instances of PTIPS.

The PTIPS GUI is a map-based CORBA client application that works with the PTIPS Data Agent to facilitate the functions of the three user types.

SCATS & SCATS Central Manager SCATS has a hierarchical structure in which a regional computer control a number of intersection traffic signal controllers. These regional computers can be connected to a Central Manager that permits SCATS users to monitor, and intervene in, the operation of the intersections controlled by regional computers.

(Figure 87, in Appendix 4, illustrates the architecture of PTIPS)

PTIPS Principles of Operation Vehicle Tracking System (VTS) The locations of public transport vehicles are conveyed to PTIPS via an AVL (Automatic Vehicle Location) Bridge. A positioning message includes a “time stamp”, vehicle identifier, route identifier, and a location identifier.

Once the relative en route location of a bus has been determined, relevant information outputs can be generated, including:

� Distance to next intersection(s)

� Traffic characteristics of the route links to the next intersection(s), eg. average travel speeds

� Signal phases to support bus passage at the intersection(s)


� Distance to next bus stop(s) on the route

� Other relevant information

Prediction of Bus Arrival Times After determining the distance to the next intersection(s), PTIPS interrogates the SPE for traffic signal status at the intersection(s). PTIPS then uses an Estimation of Plausible Trajectories Algorithm (EPTA) to estimate potential route trajectories and their probability and to provide a basis for accurate, short-term signal pre-emption to enhance public transport vehicle travel.

The capacity to perform longer-term arrival time predictions is also being developed to support real-time passenger information that responds to variable traffic conditions.

Generating Priority Requests for Public Transport Vehicles After estimating the arrival time of the public transport vehicle at the next intersection(s), PTIPS generates a request for “green windows” at the next intersection and determines the required signal priority adjustment (eg. green phase extension, early green recall, etc.), the time that the phase should be actuated, and its duration.

Updating the PTIPS Data Agent PTIPS updates the state of each public transport vehicle in the PTIPS Data Agent every time it receives a positioning message for that vehicle.

Performance of PTIPS Trials of PTIPS on the Sydney Airport Express Bus Service in 2001 indicated that PTIPS reduced both mean bus travel times (up to 21%) and the variability of bus travel times (up to 49%).

However, in one section of the trial route, PTIPS revealed a slight increase in bus travel times. Assessment indicated that priority requests appeared to be ineffective due the traffic queuing at intersections on this part of the trial route. In such circumstances, priority requests issued by PTIPS could expire before the arrival of the bus at the intersection.

This result provides evidence to support the need for integrated, multiple intervention

approaches to bus priority tailored to specific locations, corridors and traffic circumstances.

Conclusions PTIPS represents a functional, modular tool for the provision of priority for on-road public transport vehicles and (when developed) real-time passenger information.

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Appendix 5: RAPID Bus Priority System Architecture

Figure 88: RAPID System Overview (Source: “RAPID Bus Priority Discussion”, Saab ITS Pty Ltd – David Panter)

Figure 89: RAPID to SCATS Interface

Traffic SignalController(s)

SCATSRegionalManager

RAPIDRAPIDPriority

Component

SCATSITS Port

PriorityRequests Requests

Replies

SCATSCentral Manager

SCATS Interface

Status

Traffic SignalController(s)

SCATSRegional

Manager(s)


Appendix 6: International ITS & Bus Priority Examples Technical Acronyms

AVL Automatic Vehicle Localisation

BLISS Brisbane Linked Intersection Signal System

BALANCE Balancing Adaptive Network Control Method

LRT Light Rail Transit

MOVA Microprocessor Optimised Vehicle Activation

SCOOT Split, Cycle and Offset Optimisation Technique

SPOT System for Priority and Optimisation of Traffic (Sistema per la Priorità e lìOttimizzazione del Traffic)

SPRINT Selective Priority Network Technique

SPRUCE Selected Vehicle Priority in the UTMC Environment

SVD Selective Vehicle Detection

UTC Urban Traffic Control

UTMC Urban Traffic Management and Control

UTOPIA Urban Traffic Optimisation by Integrated Automation

To identify and compare a range of vehicle priority schemes, the UK Department of Environment, Transport and the Regions (DETR) sponsored a review project; UTMC-01: Selected Vehicle Priority in the UTMC Environment (SPRUCE) to determine the state of the art in selective vehicle priority. http://www.its.leeds.ac.uk/projects/spruce/

The project considered developments across the full range of applications for selective vehicle priority within urban traffic signal networks, including bus priority and Light Rail Transit (LRT) priority.

This review examined the core principles on which alternative systems of priority allocation are based and considered the benefits afforded to priority vehicles and the disbenefits to other users.

The development of bus and tram priority has been on-going in the U.K. and Europe for many years within a variety of fixed-time (passive) and dynamic (active) urban traffic control strategies, for example:

� SPRINT (fixed-time)

� SCOOT v3.1

� MOVA (isolated intersection control)

� BLISS

� BALANCE

� SPOT / UTOPIA

Within the UK, most recent experience has been obtained with SCOOT, which grants priority to buses through green time extensions and stage recalls, coupled with a variety of possible compensation strategies. Priority is considered for an individual node only.

The UTMC-01 research project examined the full range of systems developed within the U.K. and overseas, and examined the impact of their different characteristics, including:

� The base UTC system which forms the vehicle for providing priority

� Rules applied to the application of extension, recalls and compensation mechanisms

� The time horizon considered for modelling and granting priority


� Effect of data transmission delays

Selective priority systems were categorised under three headings:

� Bus priority, where priority is only given to buses, usually travelling along with other traffic

� Tram/trolley-bus/guided-bus priority, where priority is given to public transport vehicles that are constrained in their movements by tracks, overhead wires, or a guideway and which often move along segregated carriageways. (Sometimes these priority schemes are also integrated with bus priority schemes.)

SCOOT - Leeds, Leicester, London, Norwich, Southampton

Introduction

SCOOT is a centralised system in which information from SCOOT detectors on traffic flows and occupancies at the upstream end of each link is transmitted from each junction to the SCOOT computer every second over standard telephone lines. SCOOT optimises network cycle times every 2½ to 5 minutes, offsets between nodes every cycle, and green splits at each intersection at every stage. These timings are implemented on-street with the philosophy of small but frequent stage changes to react to changing traffic conditions without compromising network traffic stability. The Department of the Environment, Transport & the Regions (UK) Traffic Advisory Leaflet Traffic Advisory Leaflet Bus Priority in SCOOT® 8/00 (website: www.scoot-utc.com)

Characteristics

The SCOOT ® UTC system has a number of facilities that can be used to provide priority to buses or other public transport vehicles.

“Passive” priority can be given using the split and offset weighting parameters that can be applied to give priority to links or routes. “Passive” priority does not differentiate between vehicles. As all vehicles on the weighted link receive a similar benefit, the level of priority that can be given is generally quite low.

SCOOT ® Version 3.1 and subsequent versions incorporate a facility to provide “active” priority. For “active” priority to operate, buses need to be separately detected and priority is then given to the individual bus. This is accomplished as follows:

Bus Detection

The SCOOT ® software allows for buses to be detected either by selective vehicle detectors (SVD), ie. using bus loops and bus-borne transponders, or by an automatic vehicle location (AVL) system.

Bus loops, or AVL systems where bus detection points can be specified, have an advantage as they can be placed in optimum positions. The best location for detection is usually a compromise between the need for detection as far upstream as possible and the need for accurate journey time prediction. Also, bus detectors need to be located downstream of any bus stop, as SCOOT ® does not attempt to model the time spent at bus stops.

Depending on site conditions, a location giving a bus journey time of 10 to 15 seconds to the stop line is recommended.

Optimisation

The signal timings are optimised to benefit the buses, either by extending a current green signal (an extension) or causing succeeding stages to occur early (a recall). Extensions can be awarded centrally, or the signal controller can be programmed to implement extensions locally on-street (a local extension).

For example, for the three stage junction illustrated in “Situation A”, below, if a bus is detected towards the end of Stage “1” (which is a green period on Link “A”) it will receive an extension (ie. Stage 1 is extended) as shown in “Situation B”


Situation A

Situation B

If the bus is detected during a red period eg. Stage “2”, it will receive a recall (ie. Stage 2 and Stage 3 are shortened so that Stage 1 starts earlier), as shown in “Situation C”.

Situation C

Local Extension

Extensions awarded in the controller can be advantageous, as they eliminate 3 to 4 seconds transmission delay between out-station and in-station. That allows the system to grant extensions to buses that arrive in the last few seconds of green-time. The feature is especially important where link lengths are short, or where bus stops are located near to the stop line.

Local extensions are permitted by SCOOT® only when the saturation of the junction is sufficiently low. Techniques for programming

the signal controller have been developed and implemented in London.

Recovery

Once the bus has passed through the signals, a period of recovery occurs to bring the timings back into line with the normal SCOOT ® optimisation. Several different methods are available for use. “Situation D” is an example of how recovery might work after an extension, and “Situation E”, after a recall.

Situation D

Situation E

Likely Benefits of Bus Priority

The benefit to buses gained through providing ‘active’ SCOOT ® priority varies considerably, and is dependent on the scope for increasing or decreasing the lengths of signal stages. At junctions where the non-priority stages are already at or close to their minimum length, there is little scope for providing priority through recalls. Assuming that stages are not running close to their minimum length, the benefits of priority are then very dependent on the traffic conditions.

Reductions in delay as high as 50% are achieved when the degree of saturation is low whereas, at high degrees of saturation, the reduction in delay is around 5% to 10%.


The increase in delay to general traffic is similarly dependent on the degree of saturation. At low degrees of saturation the increase in delay to other traffic is small and insignificant, whereas at high degrees of saturation the increase in delay to general traffic can be large.

The disruptive effect of providing priority by recalls is much greater than by extensions. Giving recalls to buses on a side road can be particularly detrimental as it reduces the green time as well as disrupting the coordination along the main road.

The number of buses receiving priority is also an important factor, particularly at higher degrees of saturation. Benefit per bus decreases as bus flow increases, due to competing/conflicting priority calls, but total passenger benefit remains substantial at bus flows as high as 120 buses/hour/intersection.

Providing priority also offers a small but significant improvement in the schedule reliability of buses. Providing priority only to those buses that are behind schedule can increase the benefits to schedule reliability. Providing priority to late buses only, and therefore to fewer buses, will also tend to increase the level of benefit to those late buses. However, considering all buses, the total benefit is likely to be reduced.

Bus priority systems have also been developed which provide extensions and recalls for buses, but which are not integrated into the SCOOT UTC system. When a bus is detected, the SCOOT system is overridden to give priority to the bus at the upcoming junction. All that SCOOT does in this case is attempt to ameliorate the delay such actions cause to other traffic once the bus has passed through the junction. Such systems have been tried in Bedford and Norwich (Cranshaw and Shaw, 1995)

Control Strategy Description

The approach of a bus can trigger a green extension or stage recall depending on the current stage. To limit the disbenefit to non-priority traffic, users can set target degrees of saturation for non-priority stages, which if likely to be exceeded will inhibit the granting

of priority. Higher targets allow greater priority and more potential disruption to other road users. The duration of the extension is varied according to the journey time for the bus to pass the stop line, predicted by the traffic model.

While priority extensions and recalls are applied, the original SCOOT timings continue to operate in the background. On completion of the priority sequence, the timings are re-synchronised with the background plan using one of a range of user selectable strategies. The priority strategy contains no specific logic to compensate phases that are penalised when priority operates. However, the SCOOT split optimiser will work to redress any imbalance in queues remaining once priority ends.

For safety, a constraint is applied to the granting of recalls to ensure that no stages are skipped. For multi-stage junctions, this rule slows the introduction of the priority stage.

Priority for buses at mid block pedestrian facilities is not an option.

Variability of journey times and the presence of bus stops mean that, typically, buses are detected within approximately 100 metres of the stop line. The priority strategy is local to the node under consideration as no reference is made to the imminent arrival of buses from upstream links or to coordination with downstream signals.

Communications delays (from street to centre to street) are typically 4 to 5 seconds which effectively shifts the detection point closer to the stop line and reduces the benefits from priority. A non-centralised architecture is possible that places some logic for granting extensions within the out-station facilitating an immediate response when granting extensions.

Conclusions

Various Selective Vehicle Priority systems have been developed and implemented in many cities around the world.

Systems that can give priority to buses are the most common. Very few of the selective priority systems do more than provide an opportunity for intervention by the local traffic controller on detection of a vehicle requiring


priority. Notable exceptions are the UTOPIA system in Torino (Mauro and Di Taranto, 1989) and PRODYN in Toulouse (Henry and Farges, 1994). In both of these adaptive Urban Traffic Control (UTC) systems, Automatic Vehicle Location (AVL) is used to continuously track public transport vehicles. Predictions of delay to the public transport vehicles are used when optimising the signal settings.

Most of the priority schemes are based on a handful of possible interventions. These are:

� Extensions, where a green is extended to allow the priority vehicle through the junction

� Recalls, where a stage giving green to the priority vehicle is brought in early

� Queue jumping, where a special stage which gives priority vehicles a chance to start ahead of other traffic is triggered

� Queue management, where queues of traffic are cleared to allow the priority vehicle a clear run through a junction

� Triggering green waves, where a progression through a series of junctions is triggered by the arrival of a priority vehicle

Many of these interventions are made directly by the local controllers on the street and no attempt is made to compensate non-priority vehicles for the extra delay incurred by the passage of the priority vehicle.

However, more recent schemes attempt to make some compensatory adjustments. These usually result in lost green time being returned to stages where it has been cut, in the cycle following the passage of the vehicle.

Schemes have also been developed to be selective about giving priority in congested conditions: “conditional priority” schemes. Priority is not given if it would cause any arms of the junction to become over-saturated; resulting in queues that would not be cleared. Limits can also be placed on how often priority requests are allowed, to avoid continual shortening of opposing phases.

Technologies used to detect priority vehicles are varied. Of the selective vehicle priority schemes examined in the UTMC-01 project,

“loops and tags” was the most common method applied.

Figure 90: Vehicle Detection Technologies

0

1

2

3

4

5

6

7

8

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Some of the methods are only able to provide the information that a priority vehicle has been detected, whilst others are able to also provide extra information about the priority vehicle which can be used to make priority requests more selective.

The most common use of this information is to determine whether a public transport vehicle is adhering to its schedule, then to only give it priority if it is running late. Conflicts, where public transport vehicles on opposing stages both request priority at the same time, can also be resolved by giving first priority to the vehicle with the most passengers or the vehicle that is most behind schedule.

It is also common to have a combined public transport and emergency vehicle priority system, where emergency vehicles get a higher level of priority than public transport vehicles. In this case, there is a need to discriminate between the two different classes of vehicle.

Des

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te

E

ffect

ive:

17

May

200

4

Documents

8803 500 004 Bus Priority Measures