Advanced Transportation Engineering – 1

PEC 2

What is Traffic

Road Safety audit (RSA) is a formal procedure for assessing accident potential and safety performance of

• Existing road
• Future road
• Traffic related project or
• Project, which interacts with road users
• It qualitatively estimates and reports on potential road safety issues and identifies opportunities For improvements in safety for all road users

Course Outcomes:

After learning the course, the students should be able to:

1. Explain traffic stream characteristics and relationships between speed, flow, and density.
2. Demonstrate data collection methods for speed, volume, parking, and accident studies.
3. Illustrate different types of intersections.
4. Estimate the optimal signal timings using Webster‘s method for improved traffic flow.
5. Explain urban transport planning steps and basic demand modeling techniques.
6. Explain the role of ITS and AI in improving transportation.

Unit and Content

Unit and Content

Add a Slide Title - 3

FA-1 & FA-2

Add a Slide Title - 2

FA-1

• MCQ with Proper Reasonings

FA-2

• Poster Presentation

Add a Slide Title - 2

FA-1

• Open Book Test

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FA-2

• Poster Presentation

UNIT-1

Introduction, Objectives and Scope of Traffic Engineering; Components of Road Traffic – Vehicle, Driver and Road; Road User and Vehicle Characteristics and their effect on Road Traffic; Traffic Manoeuvres. Traffic Stream Characteristics- Relationship between Speed, Flow and Density,

Traffic Engineering & Study of its elements:

KEY TOPIC

Introduction, Objectives and Scope of Traffic Engineering

• Traffic Engineering is a specialized branch of transportation engineering concerned with the planning, design, operation, and management of traffic on roadways to ensure the safe, efficient, comfortable, and economical movement of people and goods.
• It focuses on the interaction between:
• Road users
• Vehicles
• Road infrastructure
• Traffic engineering applies scientific principles and engineering techniques to analyze traffic behavior and to develop measures that reduce congestion, delays, and accidents while improving overall road performance.

Introduction, Objectives and Scope of Traffic Engineering

The main objectives of traffic engineering are:

Safety Improvement

• To reduce road accidents and conflicts
• To enhance safety for all road users including pedestrians and cyclists

Efficient Traffic Flow

• To minimize travel time and delay
• To ensure smooth and uninterrupted movement of traffic

Optimal Use of Road Infrastructure

• To maximize capacity utilization of existing road facilities
• To reduce the need for unnecessary road widening

Traffic Regulation and Control

• To provide effective control using traffic signs, signals, and markings
• To regulate traffic movement systematically

User Comfort and Convenience

• To reduce driver stress and fatigue
• To improve travel reliability and comfort

Introduction, Objectives and Scope of Traffic Engineering

The scope of traffic engineering is broad and includes the following aspects:

• Traffic studies and surveys (volume, speed, delay, parking)
• Analysis of traffic flow characteristics
• Design of intersections and traffic control devices
• Traffic operation and management techniques
• Parking planning and management
• Road safety analysis and accident prevention measures
• Traffic regulation and enforcement support
• Application of modern tools such as Intelligent Transportation Systems (ITS)

Traffic engineering plays a vital role in urban transportation planning, highway operations, and sustainable mobility development.

Introduction, Objectives and Scope of Traffic Engineering

“Traffic engineering deals with the systematic planning, design, operation, and control of road traffic to ensure safe, efficient, and economical transportation while optimizing the use of existing road infrastructure.”

Components of Road Traffic – Vehicle, Driver and Road

• Primary components of the traffic system:
• Vehicles: Motorised (passengers cars, trucks, heavy vehicles, buses)
• Road users: Driver (drivers, pedestrians, bicyclists, passengers)
• Road: Streets and Highways (horizontal and vertical alignment)
• Traffic control devices, traffic management

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COMPONENTS OF TRAFFIC SYSTEM

ROAD USERS

HUMANS

Involved - drivers, pedestrians, bicyclists, passengers

bicyclists

pedestrians

passengers

drivers

Components of Road Traffic – Vehicle, Driver and Road

HUMANS FROM THE POINT OF VIEW OF TRAFFIC ENGINEERING

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• Active part or traffic system
• Human response is a major component of planning and design of transportation systems
• Human beings have a wide range of characteristics that influence the driving task (vision, reaction time, hearing, physical strength. personality)
• A major task is to find how to give drivers right informations in a clear and effective way with proper responses.
• Engineering designs generally accommodate the abilities of 85% of users

Components of Road Traffic – Vehicle, Driver and Road

HUMANS FROM THE POINT OF VIEW OF TRAFFIC ENGINEERING

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Which characteristics of drivers are most important in transportation?

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VISION and REACTION TIME

Note:

There are other important characteristic – hearing (i.e. horns, sirens), physical strength (steering, braking – not actual in passengers cars), personality or psychology of the driver (very difficult to quantify)

COMPONENTS OF TRAFFIC SYSTEM

ROAD USERS

VISUAL FACTORS

FIELDS OF VISION

Static (observation of stationary objects)

• depends on brightness
• increases with an increase in illumination
• depends on contrast
• time of focus (0.5 to 1.0 second)

Dynamic (detection of moving objects):

• clear vision cone 3 to 10°
• fairly clear vision cone 10 to 12°
• peripheral vision is the ability of people to see objects beyond the cone of clearest vision (160 °). Can see objects but no details and color are clear.

AFFECTS:

PLACING OF TRAFFIC SIGNS (places, height, distances, design),

SPEED ESTIMATION (important for pedestrians on pedestrian crossings or drivers within iintersections)

1. Visual acuity (is the ability to see fine details of an object)

COMPONENTS OF TRAFFIC SYSTEM

ROAD USERS

VISUAL FACTORS

2. Visual Acuity:

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• The 6/6 fraction is the globally recognized standard for visual acuity.
• The numerator (6) represents the testing distance between the patient and the eye chart, which is six meters.
• This distance is used because light rays are nearly parallel when entering the eye, allowing the eye’s focusing muscles to be at rest.
• The denominator (6) represents the distance at which a person with standard vision can read the same line of letters.
• Achieving 6/6 vision means the individual can clearly read a line at six meters that an average person is also expected to read at six meters.
• This establishes a baseline for the eye’s ability to resolve fine details.�

COMPONENTS OF TRAFFIC SYSTEM

ROAD USERS

VISUAL FACTORS

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2. Color vision: (the ability to determine one color from another)
1. Color blindness is the deficiency of this ability
2. The eye is more sensitive to the combinations of black and white and black and yellow

COMPONENTS OF TRAFFIC SYSTEM

ROAD USERS

VISUAL FACTORS

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2. Color vision: (the ability to determine one color from another)

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In India, color vision testing is required to ensure that a road user can correctly recognize traffic signal colors (Red–Yellow–Green) and important road signs.

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Ishihara test: The Ishihara test is a color vision test for detection of red–green color deficiencies. The test consists of a number of Ishihara plates, which are a type of pseudoisochromatic plate. Each plate depicts a solid circle of colored dots appearing randomized in color and size.

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https://enchroma.com/pages/normal-color-vision-test-result?v=2&lv=&l=100&m=100&s=100

COMPONENTS OF TRAFFIC SYSTEM

ROAD USERS

VISUAL FACTORS

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2. Color vision: (the ability to determine one color from another)

COMPONENTS OF TRAFFIC SYSTEM

ROAD USERS

VISUAL FACTORS

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3. Glare recovery: (the ability of a person to recover from the effects of glare after passing the light source)
1. From dark to light: 3 sec and from light to dark: 6 sec

ZEISS Online Vision Screening - Five effective vision screening checks

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https://youtu.be/gjXiG-G_srA

COMPONENTS OF TRAFFIC SYSTEM

ROAD USERS

VISUAL FACTORS

4. Depth perception: (the ability of a person to estimate speed and distance)
1. Very important for passing maneuvers in two-lane roads
2. Traffic control devices are standardized to aid in distance estimation

COMPONENTS OF TRAFFIC SYSTEM

ROAD USERS

VISUAL FACTORS

OTHER VISUAL FACTORS

COMPONENTS OF TRAFFIC SYSTEM

VISUAL FACTORS

1.

2.

3.

4.

5.

6.

7.

All of above factors can affect most drivers at particular time. Than

drivers have reduced perception of the roadway.

It is important to provide drivers with as many clues as possible as to what lies ahead of them. This is

critical for geometric elements –

drivers should never be suddenly faced with the unexpected problems.

ROAD USERS

COMPONENTS OF TRAFFIC SYSTEM

VISUAL FACTORS

1.

2.

3.

4.

5.

6.

7.

All of above factors can affect most drivers at particular time. Than

drivers have reduced perception of the roadway.

It is important to provide drivers with as many clues as possible as to what lies ahead of them. This is

critical for geometric elements –

drivers should never be suddenly faced with the unexpected problems.

ROAD USERS

COMPONENTS OF TRAFFIC SYSTEM

Traffic Signs

• The traffic signs have been divided in to three categories with the objective regulating, warning and guiding the road users.
• Mote vehicle act 1988 and IRC Traffic signs or Road signs are classified in to three caatogories
• 1 . Regulatory Signs
• 2. Warning Signs
• 3. Informatory signs

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COMPONENTS OF TRAFFIC SYSTEM

Traffic Signs

• 1. Regulatory Signs
• Definition
• Regulatory signs are mandatory signs that regulate and control traffic movement. Road users must obey these signs; violation is a punishable offence under traffic rules.
• Purpose
• To maintain order and discipline on roads
• To regulate speed, direction, and movement of vehicles
• To prevent accidents and conflicts
• Design Specifications
• Shape: Circular
• Background: White
• Border: Red
• Symbol: Black

COMPONENTS OF TRAFFIC SYSTEM

Traffic Signs

• Special Shapes:
• STOP: Octagonal, red background, white letters
• GIVE WAY: Inverted triangle, red border, white background
• Compulsory Direction: Circular, blue background, white symbol
• Examples
• Stop
• Give Way
• No Entry
• Speed Limit
• No Parking
• One Way
• Compulsory Left / Right Turn
• Importance
• These signs ensure legal compliance and safe traffic operation, especially at intersections and busy corridors.

COMPONENTS OF TRAFFIC SYSTEM

Traffic Signs

• 2. Warning Signs (1/2)
• Definition
• Warning signs (also called cautionary signs) alert road users in advance about potentially dangerous road conditions or hazards ahead.
• Purpose
• To warn drivers about geometric features or roadside hazards
• To encourage speed reduction and cautious driving
• To reduce crash risk
• Design Specifications
• Shape: Equilateral Triangle
• Background: White
• Border: Red
• Symbol: Black

COMPONENTS OF TRAFFIC SYSTEM

Traffic Signs

• 2. Warning Signs (2/2)
• Examples
• Right / Left Curve Ahead
• Hairpin Bend
• Narrow Bridge
• Road Widening Ahead
• Pedestrian Crossing, School Ahead, Men at Work
• Importance
• These signs play a vital role in accident prevention, particularly on highways, curves, construction zones, and rural roads

COMPONENTS OF TRAFFIC SYSTEM

Traffic Signs

• 3. Informatory Signs (1/2)
• Definition
• Informatory signs provide useful guidance and information to road users regarding directions, destinations, and available facilities.
• Purpose
• To guide drivers along correct routes
• To inform about nearby facilities and services
• To reduce confusion and unnecessary stops
• Design Specifications
• Shape: Rectangular
• Background: Blue
• Text / Symbol: White

COMPONENTS OF TRAFFIC SYSTEM

Traffic Signs

• 3. Informatory Signs (1/2)
• Definition
• Informatory signs provide useful guidance and information to road users regarding directions, destinations, and available facilities.
• Purpose
• To guide drivers along correct routes
• To inform about nearby facilities and services
• To reduce confusion and unnecessary stops
• Design Specifications
• Shape: Rectangular
• Background: Blue
• Text / Symbol: White

COMPONENTS OF TRAFFIC SYSTEM

VISUAL FACTORS

COMPONENTS OF TRAFFIC SYSTEM

VISUAL FACTORS

• A sign is required to be put up asking drivers to slow down to 30 km/h before entering Zone Y (see figure). On this road, vehicles require 174 m to slow down to 30 km/h (the distance of 174 m includes the distance travelled during the perception-reaction time of drivers). The sign can be read by 6/6 vision drivers from a distance of 48 m. The sign is placed at a distance of x m from the start of Zone Y so that even a 6/9 vision driver can slow down to 30 km/h before entering the zone. The minimum value of x is _______ m.

ROAD USERS

COMPONENTS OF TRAFFIC SYSTEM

VISUAL FACTORS

ROAD USERS

COMPONENTS OF TRAFFIC SYSTEM

VISUAL FACTORS

ROAD USERS

COMPONENTS OF TRAFFIC SYSTEM

PIEV Theory (Driver Reaction Time Model)

REACTION TIME INVOLVE 4 PHASES:

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PIEV stands for the four phases involved in a driver’s perception–reaction process:

P – Perception (Detection)� The object or hazard enters the driver’s field of vision.

I – Intellection (Identification)� The driver recognizes and understands what the object/hazard is and gathers relevant information (speed, distance, direction, etc.).

E – Emotion / Evaluation (Decision)� The driver analyzes the situation and decides what action to take (brake, steer, accelerate, or do nothing).

V – Volition (Response)� The physical response of the driver occurs (applying brakes, steering, gear change).

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Design values: 1.5 s – 2.5 s (which involves braking reactions)

REACTION TIME OF THE DRIVERS

(PRT – PERCEPTION REACTION TIME)

ROAD USERS

COMPONENTS OF TRAFFIC SYSTEM

ROAD USERS

REACTION TIME OF THE DRIVERS

FACTORS AFFECTING THIS PROCESS

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• Environment: Urban vs. Rural, Night vs. Day, and Wet vs. Dry
• Age: Young / Elder
• Physical Condition: Fatigue and Drugs/Alcohol
• Medical condition
• Visual acuity
• Ability to see (lighting conditions, presence of fog, snow, etc)
• Complexity of situation (more complex = more time)
• Expectancy: drivers will react more quickly to situations they expect to encounter as opposed to those that they do not expect to encounter

COMPONENTS OF TRAFFIC SYSTEM

ROAD USERS

Median Driver Reaction Time to Expected and Unexpected Information

85th-Percentile Driver Reaction Time to Expected and Unexpected Information

REACTION TIME OF THE DRIVERS

COMPONENTS OF TRAFFIC SYSTEM

BASIC CHARACTERISTICS OF THE PEDESTRIANS

Most of interactions between pedestrians and vehicles occur as pedestrians cross the roads at intersections or mid – block locations.

WALKING SPEEDS

Pedestrian walking speed in pedestrian crossing is the most important factor in the consideration of pedestrians in SIGNAL TIMING.

Note that traffic lights are designed not only to allowed vehicles to pass through the intersection but also to allowed pedestrian to cross.

Desing values could vary from 1 – 1.5 m/s.

15 m

Walking speed = 1.5 m/sec

Total time to cross the street =?

ROAD USERS

COMPONENTS OF TRAFFIC SYSTEM ROAD USERS

BASIC CHARACTERISTICS OF THE PEDESTRIANS

GAP ACCEPTANCE OF THE PEDESTRIANS

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Time intervals between vehicles arriving to the unsignalized pedestrian crossing and the behaviour of pedestrians in accepting them to cross through.

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Desing values could vary from 35 – 50 m.

Note:

A traffic light is designed not only to allow vehicles to pass through the intersection but also to allow pedestrian to cross.

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If no gap is available within an intersection or on street then alternatives arrangements such as pedestrian signals may be considered.

COMPONENTS OF TRAFFIC SYSTEM

Involved –

passengers cars, trucks, buses, motorcycles, bicycles – ALL TYPES OF VEHICLES

DESIGN VEHICLE

Design vehicles are used for setting up turning roadways, intersection curbs and lane widths. Desing vehicle is the largest vehicle which could operate on designed roadway and has three basic characteristics:

• Static characteristics:
• Weight , Size ,Turning radius
• Kinematic characteristics:
• Acceleration
• Dynamic characteristics:
• Power/weight ratios , Braking Distance

VEHICLES

COMPONENTS OF TRAFFIC SYSTEM VEHICLES

STATIC CHARACTERISTICS OF THE VEHICLES

SIZE, WEIGHT

This characteristics depends on legislation in each country (max sizes and weights of vehicles)

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Usually are vehicles divided into three or four main categories:

• Passenger cars
• Buses
• Trucks
• (special vehicles)

COMPONENTS OF TRAFFIC SYSTEM

VEHICLES

STATIC CHARACTERISTICS OF THE VEHICLES

SIZE, WEIGHT

AASHTO - US

COMPONENTS OF TRAFFIC SYSTEM VEHICLES

STATIC CHARACTERISTICS OF THE VEHICLES

SIZE, WEIGHT

CZECH STANDARD

COMPONENTS OF TRAFFIC SYSTEM

• STATIC CHARACTERISTICS OF THE VEHICLES TURNING CHARACTERISTICS
• LOW SPEED
• NEEDED FOR ESTIMATING THE MINIMUM TURNING RADIUS
• Low – speed turns are limited by the steering mechanism in vehicles
• speeds below 30 km/h

VEHICLES

HIGH SPEED

• NEEDED FOR ESTIMATING THE MINIMUM CURVE RADIUS
• High – speed turns are limited by the dynamics of side friction between roadway and tires, and by the superelevation
• speeds above 30 km/h

DISCOVER AUTOTURN

COMPONENTS OF TRAFFIC SYSTEM VEHICLES

STATIC CHARACTERISTICS OF THE VEHICLES TURNING CHARACTERISTICS

Minimum Turning Paths of Design Vehicles

The principal dimensions affecting design are: the minimum centerline turning radius (CTR), the out-to-out track width, the wheelbase, and the path of the inner rear tire (effects of driver characteristics such as the speed at which the driver makes a turn and of the slip angles of wheels are minimized by assuming that the speed of the vehicle for the minimum turning radius is less than 15 km/h [10 mph]).

COMPONENTS OF TRAFFIC SYSTEM VEHICLES

where:

v_n is design speed [km/h], v_i is initial speed and v_f is final speed [km/h],

g_n is normal gravitational acceleration 9,81 m/s², a is acceleration rate m/s² f_v is breaking force coefficient (wet pavement, tire profile 1,6 mm),

s is longitudinal slope [%], D_B is breaking distance,

DB=

Vn or (Vi –Vf)

2a

2

V

D_B = ⁿ ,

Basic equation:

Derived equation:

KINEMATIC AND DYNAMIC CHARACTERISTICS OF THE VEHICLES

BRAKING AND DECELERATION, ACCELERATION

Critical characteristic – express the ability of the vihicle to stop or decelerate

deceleration considered

as 1,7 - 2 m/s² acceleration considered as 1,2 m/s²

COMPONENTS OF TRAFFIC SYSTEM

VEHICLES

KINEMATIC AND DYNAMIC CHARACTERISTICS OF THE VEHICLES

BRAKING AND DECELERATION, ACCELERATION

Acceleration and deceleration rates of vehicles are often critical parameters in determining highway design. These rates often govern the dimensions of such design features as intersections, freeway ramps, climbing or passing lanes, and turnout bays for buses.

For lower performance vehicles

COMPONENTS OF TRAFFIC SYSTEM

STREETS AND HIGHWAYS

DEFINITION OF ROADS:

Roads, streets and motorways are

materially demarcated traffic connections, designed previously for nonrail means of transport, eventually for passenger movement.

Divided roads: Undivided road

s:

WHAT IS FUNCTION OF ROADS?

COMPONENTS OF TRAFFIC SYSTEM

STREETS AND HIGHWAYS

Road Functions

Mobility

Accessibility

FUNCTION OF ROADS

COMPONENTS OF TRAFFIC SYSTEM

STREETS AND HIGHWAYS

DIVISION OF ROADS (GENERALLY)

COMPONENTS OF TRAFFIC SYSTEM

STREETS AND HIGHWAYS

TYPICAL REPRESENTATIVES

Representative rural freeway (highway, motorway, freeway – different term in USA, EU and CR)

Representative of two lane rural road

COMPONENTS OF TRAFFIC SYSTEM

STREETS AND HIGHWAYS

TYPICAL REPRESENTATIVES

Urban communication

COMPONENTS OF TRAFFIC SYSTEM

TRAFFIC CONTROL DEVICES, TRAFFIC MANAGEMENT

• traffic signs – horizontal marking
• traffic signs – vertical signs
• traffic control devices
• other restrictions

COMPONENTS OF TRAFFIC SYSTEM

TRAFFIC CONTROL DEVICES, TRAFFIC MANAGEMENT

INTELLIGENT TRANSPORTATION SYSTEM

An intelligent transportation system (ITS) is an advanced application which aims to provide innovative services relating to different modes of transport and traffic management and enable users to be better informed and make safer, more coordinated, and 'smarter' use of transport networks.

Some of these technologies include calling for emergency services when an accident occurs, using cameras to enforce traffic laws or signs that mark speed limit changes depending on conditions.

Included: wireless communications, computational technologies, floating car data/floating cellular data, sensing, inductive loop detection, video vehicle detection, bluetooth detection, radar detection, emergency vehicle notification systems, automatic road enforcement, variable speed limits, collision avoidance systems, cooperative systems on the road, smart transportationp, payments and billing flexibility

COMPONENTS OF TRAFFIC SYSTEM GENERAL ENVIRONMENT

VILLAGE vs CITY

FORREST vs DESERT