SCOOT version 4.2 : use of flared links as a pragmatic traffic engineering solution as an alternative to expensive engineering construction.

Traffic Congestion is a major problem in most urban areas throughout the world, which has arisen from an increasing number of vehicles using the existing highway network, which cannot cater for modern demand. A combination of high cost and environmental considerations has led to the rejection of major engineering construction as the only solution to urban transportation problems and to the development of controlling movement of vehicles in urban areas. One of the Solutions of achieving improved network management is through the use of Urban Traffic Control (UTC) systems. For the majority of UTC systems in the United Kingdom (UK) and a continuing expanding number of systems throughout the world, this is achieved through the use of the SCOOT (Split Cycle and Offset Optimisation Technique) programme. In release 4.2 of the SCOOT system, the following enhancements have been incorporated: (1) Ability to model Flared Links - The modelling of flared links, which have additional lane capacity at the downstream end, is more flexible. Parameters are established to allow for the extra lanes in terms of the number and length. Validation of the saturation occupancy for the link is then by the same process as usual. (2) Recovery from Absolute Priority; (3) Reduced detection modelling. This paper will concentrate on the issues associated with the ability to model flared links.