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Possible Areas of Research in TE• Develop models to better replicate real traffic conditions• Improve understanding of traffic phenomena• Contribute to a better definition of the role of cars in cities, while assessing
their external costs and impacts• Understand and quantify how different technologies and management
strategies influence the performance of transportation systems• Develop innovative solutions to improve traffic performance and reduce
congestion both in highways and urban networks• Identify new and efficient methods for using in-vehicle and infrastructure
technologies to improve traffic conditions• Optimize the operations of transportation systems from a multi-modal
perspective
TRAFFIC ENGINEERING
• Traffic Characteristics• Traffic Studies and Analysis• Traffic Operations • Planning and Analysis• Geometric Design• Administration and Management
TRAFFIC CHARACTERISTICSTraffic Characteristics
Road User
Physical
Mental
Psychological
Environmental
Vehicular
Vehicle Dimensions
Weight of Loaded Vehicle
Power of Vehicle
Speed of Vehicle
Braking Characteristics
It consists of 1. Human Element2. Vehicular Element
ROAD USER CHARACTERISTICS
• PHYSICAL: Vision, Hearing, Reaction to different traffic situations, Strength
• MENTAL: Knowledge (of Vehicle characteristics), Skill, Intelligence, Experience,
Literacy (w.r.t. Traffic Rules as well as general Literacy)
• PSYCHOLOGICAL: Affect the reactions to the reaction to traffic situations
Reactions to distractions, drivers’ mental status, Emotions
(Attentiveness, anger, fear, impatience, general attitude
towards Traffic Rules & Regulations) and Maturity of Drivers
• ENVIRONMENTAL: Traffic stream Characteristics, Lack of Facilities (like design
of overtaking zones, uneven surface, etc.),
Motivation/Reason for coming/going (in a hurry, casual, etc.)
TRAFFIC CHARACTERISTICS
VEHICULAR CHARACTERISTICS: The criterion for Road Design is to cater for the needs of existing and anticipated (forecasted) traffic. So, the Vehicular Standards should preferably be similar throughout a country (big region), so as to provide ease of Planning and Design of Highway Networks.
TRAFFIC CHARACTERISTICS
Vehicular Characteristics
STATIC
Vehicle Dimensions
Weight of Loaded Vehicle
DYNAMIC
Power of Vehicle
Speed of Vehicle
Braking Characteristics
VEHICULAR CHARACTERISTICS: STATIC
TRAFFIC CHARACTERISTICS
Dimensions
LengthDesign of Horizontal Allignment,
Minimum Turning Radius, Width of extra pavement, Vertical Curves,
OSD, Capacity and Parking Studies
Max Length: 11 m to 18 m
HeightHeight of
Overbridges, underways,
electric lines, etc
Max Height: 3.8 m (single deck), 4.75
(Double deck)
WidthWidth of lanes,
shoulders, parking facilities, Capacity
of Roads
Max Width: 2.50 m
VEHICULAR CHARACTERISTICS: STATIC
• WEIGHT OF LOADED VEHICLE: • Affects pavement thickness and gradient. (though Limiting Gradients are governed by weight and power of the vehicle)Max Gross Weight: 12 tonnes (both axle single tyre trucks)
52.2 tonnes (tractor trailer type 3-3)(6+18+10.2+18= 52.2 tonnes)
TRAFFIC CHARACTERISTICS
TRUCK/TRACTOR TRAILER
Max Weight on Front Axle (FAW)
6 – 9 tonnes 10.2 tonnes (Type 2-2 and above)
Max Weight on Rear Axle (RAW)
6 – 18 tonnes 10.2 – 18 tonnes
VEHICULAR CHARACTERISTICS: DYNAMIC
• POWER OF VEHICLES:
Total Hauling Capacity and Power required to overcome total tractive resistance are used for the determination of Speed and Acceleration
This is useful for Traffic Regulation, Planning and Design
*Total resistance to traction consists of Inertia, Rolling Resistance, Air Resistance and Grade Resistance.
TRAFFIC CHARACTERISTICS
VEHICULAR CHARACTERISTICS: DYNAMIC
• SPEED OF VEHICLE:
It affects the design of
a. Sight Distances
b. Superelevation, Length of Transition Curves and Limiting Radius on Horizontal Curves
c. Length of Transition Curves on Vertical Curves
d. Width of pavements and shoulders
e. Design Gradient
f. Capacity of Traffic Lane
g. Design and Control Measures on Intersections
TRAFFIC CHARACTERISTICS
VEHICULAR CHARACTERISTICS: DYNAMIC
• BRAKING CHARACTERISTICS:
Depend on design and type of braking system (Mechanical, Fluid or Air Brake) and its efficiency.
Affects the safety of vehicle operations, stopping distances, spacing between two consecutive vehicles.
Thus, Highway Capacity and Overtaking Sight Distances are also indirectly affected.
TRAFFIC CHARACTERISTICS
VEHICULAR CHARACTERISTICS: DYNAMIC
• BRAKING CHARACTERISTICS:
Braking Test
Measurement of Skid Resistance under prevailing conditions (type of pavement and the desired speed of vehicle).
Assumptions:
After application of brakes and till the vehicle comes to a stop
- Wheels are fully locked, and
- Brake Efficiency is 100%.
TRAFFIC CHARACTERISTICS
VEHICULAR CHARACTERISTICS: DYNAMIC
• BRAKING CHARACTERISTICS:
Measurements required in the Braking Test:
a. Braking Distance (L),
b. Initial Speed (u), and
c. Actual Duration of brake application (t).
Skid Resistance (f), f = or f = {a = Retardation, g = 9.81 m/}Actual Skid Resistance, f’ = ηf {η= Brake Efficiency}
TRAFFIC CHARACTERISTICS
DEFINITIONS:
• Traffic Volume: Number of vehicles passing a point or cross section in a given time period.
• Traffic Density: Number of vehicles (in a lane) occupying a unit length of lane at a given instant of time.
• Rate of Flow: Number of vehicles/persons passing a point in a specified time expressed as an equivalent hourly rate (strictly specified as an hourly rate by convention, conversion to hourly rate is necessary for expressing rate of flow).
• Demand: Number of vehicles desired to travel past a point in a lane.
• Capacity: Maximum rate that is achieved in a short span or point during a time period.
Traffic Volume = (Traffic Density) x (Traffic Speed)
TRAFFIC STUDIES
The following fall under the umbrella of Traffic Studies:
• Traffic Volume Studies
• Speed Studies
• Origin and Destination Studies
• Traffic Flow Characteristics
• Traffic Capacity
• Parking Studies
• Accident Studies
TRAFFIC STUDIES
TRAFFIC STUDIES
MID BLOCK
MID BLOCK
INTERSECTION
Mid Block Counts and
Intersection Counts are done separately
• Period of Traffic Volume Studies: Depends on purpose of study
• Time and cost constraints usually demand use of simpler methods of traffic studies.
• Normally used traffic volume study periods: Peak Hour times (Morning or Evening), 12 Hour, 16 Hour, 24 Hour and 7 days.
• Common counting periods for Mid Block Counts:
1 minute, 5 minutes, 30 minutes, 1 hour (usually 5 minutes and 15 minutes durations are preferred). Normally very small counting periods are not desired as they would result in more error in extrapolating the study for a larger data set.
• Common counting periods for Signalized Intersection Counts:
Duration in multiples of cycle length.
TRAFFIC STUDIES
Data to be collected:
• Occupancy Data,
• Turning Moment data,
• Make or type of vehicles.
Challenges in the process:
• Lack of co-ordination among team members,
• Accuracy in information and Data Recording, and
• Organization of data.
Fixed FEILD DATA SHEETS in fixed format are used.
TRAFFIC STUDIES
Planning of Traffic Volume Study:
• Field Sheets should be planned and designed precisely and with clarity.
- Day Date, Time, Location, Turning Moment, Vehicle Type, etc.
- Counting Period (Duration), Total Period (example: 15 min duration for an 8 hour study)
- Climatic conditions
• Personnel should be properly trained
- How and where to use the equipment,
- Vehicle types
- Purpose of study
• Avoid too many enumerators at one place, so as not to disturb the drivers. Aim of study is to get normal data.
TRAFFIC STUDIES
Planning of Traffic Volume Study: cont…
• Choose task distribution, number of personnel, shift change, etc.
• Data recording should be feasible as per human capabilities
• Supervisors should be present on the site
• For ease of team, Mechanical Counters, Pneumatic Counters can be used.
• Pros and cons of both human and mechanical counting techniques should be known and considered.
• Breaks, whenever taken, should be properly recorded in the Data Sheet and suitable extrapolation of data for a continuous trend of traffic movement and volume should be done properly.
TRAFFIC STUDIES
• It includes Laws and Ordinances, Traffic Regulatory Measures (e.g. speed limits) and traffic control devices.
RA FI© PE® TIONS
Traffic Operations
Traffic Regulations
Traffic Control Devices
RA FI© PE® TIONSDRIVER CONTROLSe.g. Issuing driving licences
VEHICLE CONTROLSe.g. Vehicle Registrations
FLOW REGULATIONSe.g. Speed Limits, one ways, etc.
GENERAL CONTROLSe.g. Legal Framework
Traffic Regulations
• DRIVER CONTROLS
Includes Licences, driving tests, financial responsibility (in case of an accident), civil liability (citizens should follow traffic rules)
• VEHICLE CONTROLS
Vehicle registration, vehicle requirements, necessary equipment and accessories, maximum dimensions and weight for loaded vehicles (trucks), fitness of vehicles (engine, brakes in proper condition, etc.)
• FLOW REGULATIONS
Regulations for turning, overtaking, etc. Regulatory signs like one-way, pedestrian control, speed limits, etc.
• GENERAL CONTROLS
Laws in case of accidents, violation of traffic rules (Indian Motor Vehicle Act, 1939)
RA FI© PE® TIONS
These control, regulate and guide traffic.
Requirements of Traffic Control Devices• Should attract ATTENTION • Should be MEANINGFUL• There should be enough Time To Respond to those signs
Types of Traffic Control Devices• SIGNS• SIGNALS• MARKINGS• ISLANDS
RA FI© PE® TIONSTRAFFIC CONTROL DEVICES
RA FI© PE® TIONS
•Stop & Give way - Prohibitory•Speed Limit - Restriction Ends•Compulsory Direction Control - No Parking
REGULATORY
•RH or LH Curve - Steep Ascent or Descent•Hairpin Bend - Narrow Bridge or road ahead•Reverse Bend - Railway CrossingWARNING•Direction & Place Identification - Parking Signs•Facility Information - Flood Gauge•* Facility: Hospital, Petrol Pump, Food Joints, Resthouses, etc.
INFORMATORY
SIGNS
TRAFFIC CONTROL DEVICES
RA FI© PE® TIONS
TRAFFIC SIGNALSThe crossing streams of traffic are separated by TIME & SEGREGATION.
Alternatively direct traffic to stop and proceed at intersections using Red, Amber and Green lights.
Requirements:
• Draw attention
• Provide meaning
• Time to respond
• Minimum wastage of time
Factors for planning traffic signals• Volume of traffic entering the intersection • Crossing Movements
TRAFFIC CONTROL DEVICES
MARKINGS• Lines, patterns, words, symbols or reflectors on the pavements, kerbs,
sides of islands or surrounding fixed objects within or near the roadway.
• They intend to control, warn, guide or regulate the traffic.
• Their dimensions, colour, contrasts and brightness should be such that they are easily seen/identified by the road users.
• They should be installed or placed at places such that the road users have enough time to react to and follow them.
NOTE:
• Refer the PPT made by Roll Numbers 11 to 20 for road markings. It is a part of your reading material.
RA FI© PE® TIONSTRAFFIC CONTROL DEVICES
The four types of markings are
• Pavement Markings White or yellow lines on roads for division, flow directions like Centre line, lane lines, stop lines, No Passing zone markings, etc.
• Object Markings Markings on Physical Obstructions lying in and near to the traffic flow, like supports for bridges, level crossing gates, traffic islands, narrow bridges, signs and signals, etc.
• Kerb Markings Markings on kerbs and edges of islands, etc.
• Reflector Unit MarkingsUsed as hazard markers and for facilitating night visibility. Visible from a very large distance
RA FI© PE® TIONSTRAFFIC CONTROL DEVICES
TRAFFIC ISLANDSThey are raised areas constructed within the roadway to act as a physical channel through which the vehicular traffic my be guided.
They are classified as
• Divisional Islands (Dividers on roads- facilitate one way traffic)
• Channelizing Islands (at intersections- circular roundabouts, etc)
• Pedestrian Loading Islands (on bus stops (not bus stands))
• Rotary
RA FI© PE® TIONSTRAFFIC CONTROL DEVICES
ChannelizingIslands
The kerb markings are also shown here
Black & White StripsBlack & Yellow Strips
DivisionalIslands
Pedestrian LoadingIslands
Intersections are the areas where two or more continuous lanes cross each other.
Therefore, they act as areas where traffic streams merge, diverge and cross each other.
The probability of accidents are very high on intersections. Both Vehicle-Vehicle conflicts as well as Vehicle-Pedestrian conflicts.
The factors to be considered in design of intersections are:
• Relative Speed (depend on magnitude of velocity of vehicles as well as the angle between the lines of movement of the vehicles)
• Manoeuvre Areas (areas in traffic flow where two or more traffic streams merge, diverge, weave or cross each other)
PLANNING, ANALYSIS & DESIGN INTERSECTIONS
Intersections
Intersections at Grade
Channelized
Unchannelized
Rotary
Grade Separated Intersections
Over-pass
Under-pass
Interchanges
PLANNING, ANALYSIS & DESIGN INTERSECTIONS
Kindly refer Pics circulated on Whats App & e-mails for
Intersections
Or see Fig. 5.34, 5.35, 5.36, 5.37, and 5.39 in
Khanna & Justo
• Increase in the number of vehicles as well as infrastructure (offices, shopping arcades, malls, etc.)
• Absence of proper parking facilities and improper mindset of people results in faulty parking practices which results in congestion, decreased road capacity and increased probability of accidents
PLANNING, ANALYSIS & DESIGN PARKING FACILITIES
PARKING FACILITIES
ON-STREET (KERB)
ANGLE
PARALLEL
OFF-STREET
PARKING LOTS
PARKING DEMAND• The number of vehicles which park at or near to a certain location either
from morning to evening or for some period of time is parking demand for that area/location.
• Methods to compute parking demand• Record the number of vehicles in peak hour duration
Parking Demand = Volume of Traffic Entering – Volume of Traffic leaving the area
(used if parking demand is more than space available)• Count number of vehicles parked at that location w.r.t. time and duration
The count should include number of vehicles parked at different times of the day
along with the duration for which they were parked• Interview people in that area about the parking requirements and parking problems
PLANNING, ANALYSIS & DESIGN PARKING FACILITIES
PARKING CHARACTERISTICS• Study of current parking practices and general problems related to
parking.• Parking patterns (parallel or angle parking) is very important for kerb
parking as it interferes with smooth flow of traffic as well as increases the risk of accidents and also decreases the capacity of the road.
PARKING SPACE INVENTORY• Using the data of parking surveys, a map is prepared for planning places
suitable for kerb parking (along with the parking pattern), for off street parking.
• Balance between Traffic Capacity & Parking Demand is important and necessary for especially metropolitan cities.
PLANNING, ANALYSIS & DESIGN PARKING FACILITIES
ON STREET PARKING
• Parallel parking and Angle parking are decided as per the space requirements available.
• Where the length of parking lot is more, parallel parking is preferred.
• But, if length is not very much, then Angle Parking is preferred. 30˚ Parking is good when Width is less and Length is ok. 60˚ Parking is good when Width is ok and Length is relatively less (but, length is more than the width always, length over here means that it is compared to the requirement).
• 45˚ Parking is optimal from both Length and Width point of view.
• Refer Fig. 5.40
PLANNING, ANALYSIS & DESIGN PARKING FACILITIES
OFF STREET PARKING
• Read about OFF STREET Parking from book.
• Its provided where space is available at lower costs.
• That is why parking lots are in the basement or nowadays the multi-storeyed parking lots are becoming popular due to less availability of land.
• Types of Parking Lots: Self Parking and Attendant Parking (read them from the book)
• Operations in a parking lot
Entrance Acceptance Storage Delivery Exit
PLANNING, ANALYSIS & DESIGN PARKING FACILITIES
PLANNING, ANALYSIS & DESIGN TRAFFIC & TRANSPORTATION PLANNING
Changes in India over the past decade
Traffic Growth
Population Growth
National ProductivityGrowth
Require ImprovementIn Traffic Facilities
Problems
TrafficCongestion
Accidents
Causes
Improper Planning ofRoad Networks and Roadway Facilities
Poor Traffic Planning
TRAFFIC & TRANSPORTATION PLANNING
• Objectives for planning are specified
• Land use and transportation plans are developed
Plan preparation & Evaluation
• Trips between two O&D places are assigned a definite route
• Best route chosen from all routes available e.g. Google Maps- Get Directions
Traffic Assignment• Total
assumed trips are divided between public transportation and private transportation mode
• Socio-economic criterion used for assumption of % division between public and private mode
Model Split
• Trips “generated from” and “attracted from” a zone are distributed to other zones
Trip Distributio
n
• Travel demand Forecasting
• Total Trips from and to a zone are identified
Trip Generation
• Information collected regarding land use, economic activity, population, traffic characteristics and transportation facilities
Inventories
PLANNING, ANALYSIS & DESIGN
• Read/Self Analyse about jobs Divisions of Traffic Engineering units (Field Studies, Accident Analysis, Traffic Control Devices, Design & Planning, Special Investigation, Economic Analysis & Decision Theory in Engg Design and Administration)
• Kindly read the topics of slide 41 from book in detail• Also read about Highway Lighting from book