Multi-toll-type motorway stations optimal layout

摘要

The objective of this paper is to develop a toll station layout optimisation methodology based on toll plaza circulation safety analysis. Then we propose a mathematical model assessing the expected level of traffic safety associated with the toll station layout, actual or planned, due to a given configuration for toll gate types and positions. The model has been conceived in order to let the planner be able to decide the proper sequence of gate types which minimises the risk of accidents. The decision variables are mainly related to the assignment of a gate type - manual gate with operator, ETC gate, semiautomatic or short stop gate -to each gate position in the station. The resulting multi-toll-type assignment model, or MTTA, takes into account the probability of interaction between pairs of traffic streams originated from the different lanes of the highway and directed to specific gate types; different severity and risk indices are associated both with vehicle types and with destination gate types. The computational tests have been performed on observed data collected during several hours of video-camera images recorded in five different motorway multi-type toll plazas located in Tuscany (Italy). Our results support the evidence that gates associated to higher risk traffic flows, e.g. traffic directed to ETC gates which approaches the toll station at speeds significantly above the average, should be locate in a central position with respect to other gate types. Moreover, the experimental results disagree with the general operations practice of many Italian motorway Agencies, which usually place ETC gates on the far side of the toll plaza.