An on-line procedure for estimating current capacity

In this report the development and off-line testing of a procedure for estimating the current capacity at a motorway cross-section are described, the adjective "current" referring to prevailing roadway and weather conditions. Such a procedure is important for dynamic traffic management applications, such as ramp metering and rerouting which crucially depend on reliable estimates of current capacity. The procedure is based on the combination of an on-line estimation of the "current" Fundamental Diagram, with the maximal occupancy of a loop detector that may be acieved at a cross-section under free-flowing conditions. Suitable representations for the Fundamental Diagram and the maximal occupancy are investigated using a large set of data. The on-line procedure itself is developed and tested for different sets of weather conditions. The procedure seems to respond well to changing weather conditions (dry/wet). A special version of the procedure is presented which is suitable for road-side implementation: both the representation of the Fundamental Diagram and the maximal occupancy (which may be location specific) can be estimated on-line.