Monitoring and modelling of controlled motorways

A microscopic model that simulates the behaviour of vehicles on a multilane carriageway has been developed at TRL for the Highways Agency (HA). The model known as SISTM (Simulation of Strategies for Traffic on Motorways) has been calibrated and validated during its development by using traffic data collected from motorways in the UK. SISTM has recently been further developed for the HA so that it replicates the full functionality of a MIDAS system. The objective of including MIDAS in SISTM is to model the M25 controlled motorway and other MIDAS schemes and recommend optimum MIDAS parameter settings for different operational requirements. SISTM also includes additional performance outputs such as exhaust emissions and fuel consumption. This paper describes some of the key results from the monitoring and their implications for the present system. It provides a summary of how the HA´s microscopic model SISTM has been developed in order to describe the controlled motorway environment more accurately and concludes with a discussion of how the two aspects have been combined