The development of Intelligent Transport Systems (ITS) and the application in traffic management, control and information, help make more efficient use of the existing road infrastructure and reduce congestion and externalities. Micro-simulation can provide a more effective tool than traditional traffic model for the assessment of the effectiveness of ITS, which often requires interaction between individual vehicles and the new systems to be modelled. Micro-simulation can be used to develop new ITS systems, optimise their effectiveness and provide realistic training for system operators and users prior to operation in the real world.
The SMARTEST project was directed towards modelling and simulation at micro level of dynamic traffic management problems caused by incidents, heavy traffic, accidents and road works. The SMARTEST application areas are incident management, intersection control, motorway flow control, dynamic route guidance and regional traffic information.
The SMARTEST specific objectives were to:
- review current micro-simulation models and identify gaps;
- investigate how the existing models can be enhanced to fill the identified gaps;
- incorporate the findings into a best practice manual.
The state-of-the-art review has revealed the existence of fifty-seven micro-simulation models, which mostly use a time stepping approach and simple car following, lane changing and gap acceptance laws to govern vehicle movements. Most of the models have animation capabilities but very few a graphical network builder. Most provide outputs that allow efficiency indicators to be assessed, about half allow environmental objectives to be assessed, very few produce outputs to measure safety or comfort.
The gaps which have been identified between existing capabilities and users' requirements are: a need for incident management, adaptive signal control, public transport priority, ramp metering, variable message signs, dynamic route guidance, public transport stops, vehicle detectors, roundabouts, parking and traffic calming measures. Better user interfaces and more work on validation of the existing models is also needed.
Generic models and procedures have been developed to fill the most important gaps. Improvements have been made to four models: AIMSUN2, DRACULA, NEMIS, SITRA-B+.
The best practice manual, which covers all the SMARTEST application areas, includes:
- methodology for defining scheme objectives and relating them to performance indicators;
- guidelines for selecting a suitable micro-simulation model;
- calibration and validation procedures;
- procedures to help ensure that scheme evaluation tackles issues such as robustness of conclusions, introducing variability and statistical significance;
- recommendations concerning when and how micro-simulation should be used.
The SMARTEST project has provided road network managers with an improved set of tools and procedures to assess the impacts of road transport schemes and interventions. Considerable economic savings can be made, as the assessment will be possible without field experiments. The assessment of the usefulness of improved urban traffic control, and information and guidance systems can lead to new industrial developments. Improved micro-simulation tools will result in better knowledge and understanding of mobility, traffic flows, their interactions and interdependencies. Further developments are expected in the assessment of environmental and safety impacts.