OPTIMIZING THE EXISTING INFRASTRUCTURE BY CONTROLING CONGESTION AND TRAFFIC FLOW ON A HEAVY TRAFFIC MOTORWAY : THE SUCCESSFUL CHALLENGE OF ASF

Traffic volume on the A7 motorway, in the Rhone Valley, keeps on increasing so much that it causes a significant and recurrent worsening of traffic conditions even out of the major summer migrations context. Deterioration in the level of service provided by the A7 motorway is closely linked to the current capacity of the corridor. Given this situation, and in the face of very few possibilities of widening the motorway, ASF has undertaken to improve its operating methods in order to face the worsening of traffic conditions along this corridor. To do so, ASF launched in 2003 several prospective studies aimed at setting up innovative road operation devices in order to best manage the highest trafficked areas of its network. Among these studies, ASF started up some reflections on various matters such as ramp metering, dynamic pricing, ban on overtaking for heavy vehicles and speed control. The A7 motorway, facing more than 75.000 veh/day (AADT) and almost 165.000 veh/day during peak-periods, is a preferential axis for the implementation of such devices. Thus ASF experimented, in summer 2004, with a dynamic speed control device on a 90 km long section of the northbound A7 motorway, being the most sensitive part of the axis. After positive evaluation results, it was perpetuated then extended, in summer 2005, to the other direction (equating to 250 km under speed control in total). For the covering abstract see ITRD E139491.