Business Logistics 420Public Transportation

Lecture 20: Transit System Design

Lecture Objectives

• To understand the basic elements of transit system design

• To appreciate the different transit system route configurations

• To know the basic principles of good route design

• To understand other aspects of system design such as schedules, stop location

Elements of Transit System Design

• Overall system -- route interrelationship

• Individual route design

• Scheduling

• Stop locations

• Vehicle Selection

System Considerations• Service area definition• Location of major generators• Route pattern -- network

– Radial -- circumferential

– Grid -- rectangular

– Combination

– Irregular

• Route spacing• Transfers -- inter and intra modal• Marketing considerations

Chicago Loop -- Grid Network

Washington Metro -- Radial

CATA -- Radial System

ATA -- Bradford, Pa -- Irregular

Route Design Guidelines

• Use direct routing where possible

• Through routing is preferred to cycle routing

• Reverse or loop routing should be used sparingly

• Routes should begin and end at major generators

Route Design Guidelines (Continued)

• Routes should be spaced about 1/2 mile apart

• Routes should provide direct service -- circuity ratio (actual route miles/direct auto travel) should not exceed 1.33

• Initial route design assumes average speed of 12 miles per hour

CATA - P Route -- Through Routing

CATA C Route -- Poor Circuity

CATA -- CS Route --Reverse or Loop Routing

Factors Influencing Route Design

• Demand– spatial arrangement– special generators

• Urban environment– street network (one-way streets)– congestion

• Management Considerations– driver scheduling– labor rules

Factors Influencing Route Design (Continued)

• Intermodal Coordination– Rail/bus/paratransit– Intercity facilities (rail, bus, air)

• Political Considerations– Equity– Pressure

Scheduling Considerations

• Two major issues– Headway – time between vehicles Ex: 15 minute

headway represents four buses per hour

– Timing of arrivals at points along the route

• Factors to consider– quality of service (frequency)

– transfers

– easy memorization

– driver labor requirements

Scheduling Considerations (Continued)

• Setting headways– Maximum headway (fewest minutes between

vehicles) set based on capacity needed to meet demand

– Minimum headway based on policy decisions, e.g., all routes should have no less frequent service than 30 minutes in the peak and 60 minutes off peak

Scheduling Considerations (Continued)

• Setting arrival times– Independent scheduling

• Most common approach

• OK if short headways, but may cause transfer problems if long headways

– Pulse scheduling – timed transfers• Attractive approach for systems with long headways

• Improves service quality

• Hard to implement due to space constraints at stops and variability of travel times

Stop Locations• Operations

– location (Near side, far side, mid block)– peak number of buses at stop at any given time

• Quality of service– near destinations– spaced 750 ft or more apart to maintain

operating speed– adequate waiting area -- shelter

Stop Locations (Continued)• The urban environment

– parking restrictions– turns

• Special concerns in “Edge City,” “big box” environment– bus stop near store entrances rather than across

sea of parking– circuity concerns if store too far from road

Vehicle Selection

• Size of vehicle– Peak loads (goal to provide 5 sq ft/psgr so 8 x

40 ft bus = 320 sq ft or 64 passengers max.– Traffic conditions

• street width

• turning radius

• Number of vehicles– Peak hour requirement plus 10% spares

Miscellaneous System Design Issues

• Special service types– “freeway flyers”– skip stop operation– local vs express

• New service types– service routes (fixed-route with deviations)– paratransit feeder services

Study Questions• What are the major aspects of transit system

design?

• What are the basic types of transit route network configurations?

• What are the basic route design guidelines?

• What are “good” route designs? What are “poor” designs?

• What factors influence scheduling decisions?

Study Questions (Continued)

• What factors are important when selecting vehicle size and numbers?

• Pick up a CATA Ride Guide in the HUB, Kern, or inside the doors to Willard (“new” building side on Pollock Rd.) to serve as reference for this lecture