CHAPTER 1 Definition of Traffic Engineering
The Institute of Transportation Engineers defines traffic engineering as a subset of transportation engineering as follows
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. The definition represents a broadening of the profession to include multimodal transportation systems and options, and to include a variety of objectives in addition to the traditional goals of safety and efficiency. The traffic or highway engineer must understand not only the basic characteristics of the driver, the vehicle, and the roadway, but how each interacts with the others. Information obtained through traffic engineering studies serves to identify relevant characteristics and define related problems. Traffic flow is of fundamental importance in developing and designing strategies for intersection control, rural highways, and freeway segments. Objectives of Traffic engineering
1. Safety 2. Speed 3. Comfort 4. Convenience 5. Economy 6. Environmental compatibility Most of these are self-evident desires of the traveller. Safety
The principal goal of the traffic engineer remains the provision of a safe system for highway traffic. Driving under the influence (DUI) and driving while intoxicated (DWI) has resulted in lowering of safety .The objective of safe travel is always number one and is never finished for the traffic engineer. Speed
Most of us want our trips to be fast, comfortable, convenient, cheap, and in harmony with the environment. All of these objectives are also relative and must be balanced against each other
and against the primary objective of safety. While speed of travel is much to be desired, it is limited by transportation technology, human characteristics, and the need to provide safety. Comfort and convenience
Comfort and convenience are generic terms and mean different things to different people. Comfort involves the physical characteristics of vehicles and roadways, and is influenced by our perception of safety. Convenience relates more to the ease with which trips are made and the ability of transport systems to accommodate all of our travel needs at appropriate times. Economy
Economy is also relative. There is little in modern transportation systems that can be termed “cheap.” Highway and other transportation systems involve massive construction, maintenance, and operating expenditures, most of which are provided through general and user taxes and fees. Nevertheless, every engineer, regardless of discipline, is called upon to provide the best possible systems for the money. Environmental compatibility Harmony with the environment is a complex issue that has become more important over time.
All transportation systems have some negative impacts on the environment. All produce air and noise pollution in some forms, and all utilize valuable land resources. In many modern cities, transportation systems utilize as much as 25% of the total land area. “Harmony” is achieved when transportation systems are designed to minimize negative environmental impacts, and where system architecture provides for aesthetically pleasing facilities that “fit in” with their surroundings. The traffic engineer is tasked with all of these goals and objectives and with making the appropriate tradeoffs to optimize both the transportation systems and the use of public funds to build, maintain, and operate them.
Function of Traffic Engineer
The functions of traffic engineering include the following 1. Collection, analysis and interpretation of data pertaining of traffic
One of the important functions of traffic engineer is to organize and implement various surveys and studies aimed at collection of data pertaining to traffic characteristics. Such studies include 1. Origin and destination studies 2. Volume counts 3. Speed, travel time and delay measurements
4. Accident statistics 5. Parking characteristics 6. Pedestrian behaviour and use of streets 7. Capacity studies 8. Economic losses due to inferior traffic facilities The data collected by the above studies are analysed by the traffic engineer and interpreted to take advantages of the observed regularities. Accurate understandings of the scientific phenomena behind these irregularities enable the traffic engineer to select appropriate solution to problems
2. Traffic and Transportation planning
The traffic engineer is concerned with the preparation of traffic and transportation plans to ensure a safe, orderly and fully integrated transportation system. This phase of activity concerns itself with the relation of land use with transportation and study of travel characteristics. Based on the analysis of the results of such study, mathematical models are formulated to predict how a system will behave under a given set of conditions. Alternative solutions for the development of street system are then thought out and are evaluated for their comparative merits and demerits. The optimal solution is then selected and implemented.
3. Traffic Design
This part of the traffic engineer’s function concerns itself with geometric design of highway and streets, intersection design, schemes for grade separated inter-changes, design of offstreet and on-street parking facilities and design of terminal facilities for trucks and buses. In the field of geometric design, the functions of the highway engineer overlap and there is need for closer co-operation and consultation between the two.
4. Measures for operation of traffic
For efficient and safe operation of traffic, the traffic engineer has to take recourse to a number of measures such as: Legislation and enforcement measures for regulating the driver, vehicle and road users like the pedestrians, cyclists and motor-cyclists.
Management measures such as one-way streets, prohibited turnings at junctions and tidal flow arrangements, exclusive bus lanes etc. with a view to get the maximum use out of the available street facilities Measures for regulation of parking of vehicles Traffic control devices such as traffic signs, traffic signals, pavement markings and channelization techniques to guide and secure the safe and efficient flow of traffic.
5. Administration
One of the functions of the traffic engineer is to organise and administer the various programmes intended to secure safe and efficient traffic in towns and cities. In this field he is closely associated with the legal and administrative framework of the city department dealing with education and enforcement measures.
Scope of traffic engineering
Road traffic has been growing at a very rapid rate in India during the past three decades. The number of motor vehicles has been growing at a rate of around 10 percent per annum. The growth rate of various vehicles has been as under: Cars: 7- 10 Percent Buses:5-10 percent Trucks:6-15 percent Two wheelers: 15-17 percent The production of motor vehicles has been growing at a rapid rate, as a result of this steep growth of motor vehicle population, the traffic on the roads has been increasing, both in terms of volume and intensity. The investment on roads have not kept pace with the growth of traffic, with the result there is severe congestion on the roads. Speeds are low and vehicle operation costs are high. Accident rate is usually high. Traffic engineering measures provide a valuable tool to understand the problems and evolve suitable measures to overcome the deficiencies.
