road traffic
Introduction
Highway traffic operations are influenced by the behavior of drivers. A highway can be used by a finite number of vehicles, and the driver perceived safe distances between vehicles determine this limit. For a given speed, as distances become shorter, more vehicles can use the highway. Both the volume of drivers choosing to use the highway (demand) and the maximum volume that can be served (supply) depend on driver behavior. Congestion results from too many people attempting to reach their destinations at the same time using the same highways. The combination of demand, capacity, and certain infrastructure features (traffic control devices) determines how drivers perceive the traffic conditions. Transportation agencies strive for economical solutions to congestion that satisfy a majority of highway users.
A traffic signal installation is a power-operated device which informs motorists or pedestrians when they have the right of way at a particular intersection. The first traffic signal was installed in London in 1868 and used semaphore 'arms ' together with red and green gas lamps. Unfortunately, it exploded, putting an end to this sort of control for 50 years. However, in 1918 the first three colored light signals were installed in New York and in 1925 they started to be used in Great Britain. At the beginning of the 1930 's an attempt at making the signals more `intelligent ', or vehicle responsive, was tried in America, using microphones at the side of the road, requiring drivers to sound their horns.
This was obviously not too popular and the first traffic detectors - electrical and pneumatic were invented. Traffic signals are now used throughout the world, using the three light signals of Green, red and amber. Also, by convention, these are normally arranged vertically with the red signal at the top and the green light at the bottom. This also helps people who are colour blind - both drivers and pedestrians to identify the
Highway traffic operations are influenced by the behavior of drivers. A highway can be used by a finite number of vehicles, and the driver perceived safe distances between vehicles determine this limit. For a given speed, as distances become shorter, more vehicles can use the highway. Both the volume of drivers choosing to use the highway (demand) and the maximum volume that can be served (supply) depend on driver behavior. Congestion results from too many people attempting to reach their destinations at the same time using the same highways. The combination of demand, capacity, and certain infrastructure features (traffic control devices) determines how drivers perceive the traffic conditions. Transportation agencies strive for economical solutions to congestion that satisfy a majority of highway users.
A traffic signal installation is a power-operated device which informs motorists or pedestrians when they have the right of way at a particular intersection. The first traffic signal was installed in London in 1868 and used semaphore 'arms ' together with red and green gas lamps. Unfortunately, it exploded, putting an end to this sort of control for 50 years. However, in 1918 the first three colored light signals were installed in New York and in 1925 they started to be used in Great Britain. At the beginning of the 1930 's an attempt at making the signals more `intelligent ', or vehicle responsive, was tried in America, using microphones at the side of the road, requiring drivers to sound their horns.
This was obviously not too popular and the first traffic detectors - electrical and pneumatic were invented. Traffic signals are now used throughout the world, using the three light signals of Green, red and amber. Also, by convention, these are normally arranged vertically with the red signal at the top and the green light at the bottom. This also helps people who are colour blind - both drivers and pedestrians to identify the
References: 1. UNIVERSITY OF AFRICA- Road Structure and Traffic Control Device module - 2013 (extract from Road maintenance Hand Book Volume iv). 2. BENT THAGESEN : Highway and traffic engineering in developing countries 3. Cannell, A. E. R. and Kaestner, C. Some Aspects of Area Traffic Control in Semi-Developed Countries. 4. Traffic engineering acrd Control. 1983. Companhia de Engenharia de Transito -CET. 5. Department of Transport. Junction Layout for Control by Traffic Signals. Highway, Safety and Traffic Advice Note TA 6. Gardner, G, Fouracre, P.R. and Jacobs, G.D. Traffic Management. 7. SCOOT: Traffic Responsive Method of Coordinating Signals. TRRL Report 1014. Transport and Road Research 8. Willumsen, L.G. and Coeymans, J.E. Research into the Value of Area Traffic Control Techniques in a Developing Country.