Transportation Engineering Lecture 1: Introduction Dr. Bidisha Ghosh

Lecture /08/2015 Syllabus Traffic Engineering Transport & Environment Transport & Energy

Lecture /08/2015 Reference Material Some of the material for this lecture is taken from course CE 453 Lecture 7http://

Lecture 1 Transportation Engineering The definition by Institute of Transportation Engineers (ITE) : Transportation engineering is the application of technology and scientific principles to the planning, functional design, operation, and management of facilities for any mode of transportation in order to provide for the safe, rapid, comfortable, convenient, economical, and environmentally compatible movement of people and goods. 4 28/08/2015

Lecture 1 Traffic Engineering Transport or transportation is the movement of people and goods from one location to another. Transportation is necessary as there is a spatial distribution of activities & resources. Spatial characteristics generate demand for transport. To fulfil the demand there are different modes of transport. Most predominant is road transport. Traffic engineering is that phase of transportation engineering which deals with the planning, geometric design and traffic operations of roads, streets, and highways, their networks, terminals, abutting lands, and relationships with other modes of transportation. 5 28/08/2015

Lecture 1 Primary Objectives: 1.The principal objective of traffic engineering is to provide a safe system for road traffic including pedestrians and bicycles. 2.Provision of efficient management & operations of road transport network 3.Other objectives can be: –Sustainability –Environmental impacts –Comfort & convenience of the user –Economy 6 28/08/2015

Lecture /08/2015 Traffic System Components: 1.Cars, Buses, Trucks, Taxis --- Vehicular Traffic 2.Motorway, Highway, Urban Arterial, Rural roads --- Road Conditions 3.Young, Drunk, Experienced, Learner’s License --- Driver Characteristics 4.Rainy, Sunny, Foggy, Night-time conditions --- Environmental Conditions 5.Signalised/Unsignalised --- Control Devices

Lecture 1 Vehicle Characteristics Dimension –For road design it is important to have design vehicles having dimensions representative of actual fleet Acceleration performance –The weight-to-power ratios vary significantly for vehicles Braking Performance –Depends on a tire conditions & type, road surface type & condition, and the slope/grade of the road –Important to calculate safe stopping distance 8 28/08/2015

Lecture 1 Vehicle Characteristics Braking Performance Friction is a function of pavement condition (wet, icy), tire, and roadway surface Grade is expressed as a decimal. Frication + grade together determines the deceleration 9 28/08/2015

Lecture 1 Vehicle Characteristics Sight Distances Distance a driver can see ahead at any specific time Must allow sufficient distance for a driver to perceive/react and stop, swerve etc when necessary Different types of sight distances, Stopping Decision Passing Intersection 10 28/08/2015

Lecture 1 Safe Stopping Distances Stopping sight distance (SSD) It is the length of roadway that should be visible ahead of you, in order to ensure that you will be able to stop if there is an object in your path. It is composed of two distances, –Distance traveled during perception/reaction time –Distance required to brake the vehicle 11 28/08/2015

Lecture 1 Vehicle Characteristics Decision Sight Distance When situation is unexpected or driver must make unusual maneuvers or under difficult-to- perceive situations. It does not depend on stopping but on manoeuvring safely and efficiently. Passing Sight Distance It is the length of roadway that the driver of the passing vehicle must be able to see initially, in order to make a passing manoeuvre safely /08/2015

Lecture 1 Driver Characteristics 1 Variable driver types Age, gender, physical condition (people with disability, alcohol, etc.), mental capabilities, skill (self perception of the skill level !!), attitude Overall it can be considered that there is a wide range of users of the road transport facilities 13 28/08/2015

Lecture 1 How to address variability in driver characteristics? Most traffic engineering designs are based on a single characteristics value that can safely accommodate majority of driving population. An 85 th percentile value is chosen for most user related parameters (say, braking reaction time, walking speed etc.) 14 28/08/2015

Lecture 1 Perception/Reaction Time 15 28/08/2015 Driver Characteristics 2 15 PIEV Perception Sees or hears situation (sees deer) Identification Identify situation (realizes deer is in road) Emotion Decides on course of action (swerve, stop, change lanes, etc) Reaction (volition) Acts (time to start events in motion but not actually do action) Foot begins to hit brake, not actual deceleration

Lecture 1 Perception/Reaction Time Range: 0.5 to 7 seconds Environment: Urban vs. Rural/Night vs. Day/Wet vs. Dry Age Physical Condition: Fatigue/Drugs/Alcohol Distractions medical condition visual acuity ability to see (lighting conditions, presence of fog, snow, etc) complexity of situation (more complex = more time) complexity of necessary response expected versus unexpected situation (traffic light turning red vs. dog darting into road) 16 28/08/2015 Driver Characteristics 3

Lecture 1 85 th percentile driver’s reaction time 17 28/08/2015 Driver Characteristics 4

Lecture 1 Visual Acuity: Ability to see fine details Static (stationary objects such as letters) Dynamic (ability to detect moving objects) Depth perception Glare recovery Peripheral vision – Key criteria in determining placement of traffic signs 18 28/08/2015 Driver Characteristics 5

Lecture 1 Road Characteristics Geometric characteristics of road –Horizontal alignment –Vertical alignment –Other geometric elements (water drainage etc.) –Highway Design (no. of lanes etc.) 19 28/08/2015

Lecture 1 Traffic Control Traffic Control Devices To be effective, a device must, 1.Fulfil a specific purpose 2.Command attention 3.Convey a clear simple meaning 4.Command respect of road users 5.Give adequate time for proper response Broad Category of Traffic Control Devices, –Traffic Marking –Traffic Signs –Traffic Signals 20 28/08/2015

Lecture 1 Traffic Control Devices Traffic Markings, –Longitudinal Markings –Transverse Markings –Object Markings and delineators –Word/ Symbol Markings, –Intersection Markings Traffic Signs, –Regulatory Signs –Warning Signs –Guide Signs Traffic Signal Control (covered in details in SS year) 21 28/08/2015