The aim of dynamic traffic management (DTM) is to guarantee optimal use of the existing road infrastructure. A so called `buffer' will be introduced as a potential DTM-tool, the purpose of which is to prevent gridlock on the main motorway network. Congestion occurs in uninterrupted traffic flows when more vehicles enter the upstream end of a road section than can get out at the downstream end. A queue of vehicles will be formed, which may lead to blocking of turning lanes and/or upstream intersections. If vehicles are lined up in a buffer widthwise (with so called `excess lanes') instead of lengthwise as in the existing situation, the queue length will be shortened and blocking effects can be avoided. Specific buffer can be avoided. Specific buffer design criteria for buffer layout in addition to general road design criteria have been developed. Based on traffic flow theory the buffer dimensions and effects on traffic flow can be estimated. For this application acceptable assumptions have been made about the existence of a maximum accepted trip time loss, a linear fundamental diagram and a uniform distribution of intensity and density over lanes. An application example demonstrates that the buffer concept is a promising DTM-option, especially when removal of the bottleneck in the short term is difficult. (A)
Abstract