Application of an on-line procedure for estimating capacity under prevailing roadway and traffic conditions

The development and offline testing of a procedure for estimating the current capacity at a motorway carriageway are described. The procedure is specifically aimed at estimating capacity while the traffic is still free-flowing. It is based on the combination of an online estimate of the current fundamental diagram, and the maximal occupancy of a loop detector that may be achieved at a carriageway under free-flowing conditions. Suitable representations for the fundamental diagram and the maximal occupancy are based on investigations using a large set of data. The online procedure itself is developed and tested for different sets of weather condition. Good responses of the procedure to changing weather conditions (dry/wet) have been obtained. It is concluded that the procedure offers promising perspectives for eventual application in dynamic traffic management systems. Suggestions for future research are given.