Optimizing the Existing Infrastructure by Controlling 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. The objective of the experiment conducted by ASF during summer 2004 was to assess both the performance and feasibility of a life-size speed control system over a heavy traffic section. The goal was to better grasp the impact of this type of system on the flow of traffic and to quantify the gains achieved with respect to capacity, safety and comfort. With respect to infrastructure capacity, the objective aimed more specifically at delaying the occurrence of congestions on the controlled section by anticipating traffic destabilization regimes. In addition to the speed control system, a campaign to raise drivers’ awareness of their speed sought to promote compliance with the speed limits set by the system and thus reinforce the expected effect of the speed control system on the traffic load carrying capacity of the corridor. With respect to safety, the lower speed limit sought to reduce the speed differentials between the vehicles on the same traffic lanes thus limiting the risk of rear-end collisions. Likewise, standardizing the speeds driven on the different lanes also aimed at limiting the appeal of the fast lanes, thus reducing accident-causing lane changes during heavy traffic situations. The addition of the awareness-raising information on the speeds in use aimed at reinforcing compliance with the prescribed speeds and thus reducing the number of vehicles driving over the speed limit. With respect to driver comfort, a more subjective criteria, improved traffic fluidity reduces the “stop and go” effect and the drivers’ driving load. The objective of improving driving conditions was to promote less aggressive driving behavior by reducing the “infrastructure use conflicts”. This was reinforced by the presence of the awareness-raising information on the speeds actually being implemented.

• Corporate Authors:

  World Road Association (PIARC)

  La Grande Arche, Paroi Nord, Niveau 5
  F-92055 La Defense Cedex,   France 
• Authors:
  • Lisbonis, M
• Conference:
  • Choice for Sustainable Development. Pre-Proceedings of the 23rd PIARRC World Road Congress
  • Location: Paris , France
  • Date: 2007-9-17 to 2007-9-21
• Publication Date: 2007

Language

• English

Media Info

• Media Type: CD-ROM
• Features: Figures;
• Pagination: 8p
• Monograph Title: The Choice for Sustainable Development. Pre-Proceedings of the 23rd PIARC World Road Congress

Subject/Index Terms

• TRT Terms: Freeways; Infrastructure; Level of service; Speed control; Summer; Traffic congestion; Traffic flow; Traffic speed; Traffic volume
• Uncontrolled Terms: Peak loads (Traffic)
• Subject Areas: Highways; Operations and Traffic Management; Planning and Forecasting; I72: Traffic and Transport Planning;

Filing Info

• Accession Number: 01081050
• Record Type: Publication
• Files: TRIS
• Created Date: Nov 26 2007 9:54AM