Traffic Operation Optimization of Highways with Ramp Metering Employing Mathematical Programming Models

Transportation management on both the supply and demand sides, due to ever increasing traffic problems is nowadays, considered as a crucial issue by transportation planners and engineers even in developing countries. Ramp metering as a transportation supply management measure with noticeable improvements in performance of the existing infrastructure and more effective use of the limited resources with comparatively little cost, is the focus of this paper. A mathematical programming model is designed to optimize the traffic volume on highways and their ramps via controlling the entrance volume of vehicles through different on-ramps, as decision variables. Flow conservation constraints are the major constraints in this model. A section of Sadr Highway is analyzed as the case for empirical study, for which traffic surveys including traffic counts is administered for the whole section under study. Results show that the flow of vehicles in the selected highway section can increase up to about 6 percent. The adversely high effect of Shariati on-ramp on the whole system under study indicates that its traffic flow can be reduced to 13 percent, with still positive effect on the whole system. Modarres on-ramp is the only ramp that is acting below its boundary limit and needs not any metering in the current circumstances.