Turbulent traffic on motorways - the impact on safety and capacity

Subject

The impact of motorway design on turbulence in the traffic stream, and its impact on safety and capacity.

Scientific challenges

Turbulence is a complex combination of many different elements, which are hard to assess as a whole. Only few data is available and the available microscopic simulation models are not accurate enough. Therefore new data needs to be collected, existing models need to be improved or new models need to be developed.

Societal relevance

The general hypothesis is that the level of generated turbulence by motorway ramps is effected by certain conditions, such as road design, traffic characteristics such as volume and speed. These conditions have an effect on driving behaviour. The resulting manoeuvers drivers take have an effect on traffic safety and operation. The theoretical background of our current motorway design guidelines are unclear. This is a problem in two ways:

1. It is unclear if the current design guidelines lead to an optimal design;
2. The exact impact of deviating from the guidelines on safety and operation is unclear.

From an economic and a land use point of view deviating from guidelines might be beneficial. For a good trade-off there is a need for a method to assess the (expected) level of turbulence of a design, or an existing situation. This method should be able to quantify the resulting level of turbulence and its influence on traffic safety and traffic operations.