Traffic Control in the City of Le Mans

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SEM started the work in 2001, which was scheduled for completion in 2008. The actual construction operations were carried out between 2005 and 2007. The tramway comprises 29 stops spread over two lines. The tramway has the right of way in traffic. Consequently, precise coordination between tramway, the intersection controllers and the traffic signals is required.

The tramway route is 15.4km in length and has 57 intersection controllers. Twenty three tram trains are in operation. The ETDE company, a supplier of integration solutions and subsidiary of the Bouygues Group, took over installation of the network in 2007 in collaboration with a subsidiary of the FAYAT Group, FARECO, the leading company in the field of planning traffic signals with three colored lights.

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The aim of the network is to link the intersection controllers for the tramway to each other to manage the right of way at the traffic signals. The FARECO intersection controllers communicate with each other via Ethernet (native) incorporating the DIASER standard (standard dialog for control systems). This standard, first used in May, 1998, was introduced to ensure the necessary safety in traffic control. The use of Ethernet offers two advantages: the first advantage is the possibility of controlling all the traffic signals from the central location in Antarès over a distance of 15.4km across a monomode fiber-optic network. The second advantage is the ability to ensure the best possible communication of the intersection controllers with each other. The exchange takes place in real time. If one controller recognizes a passing tram train through its detectors, the information about an approaching tram train must be forwarded to the subsequent controllers. The information is transmitted by means of a general “Broadcast”.

Project parameter

  • Broadcasts are administered through the switches
  • Switches must withstand the effects of the environment
  • Switch dimensions must be small
  • The network must provide comprehensive diagnostics
  • The network must be secured

Solution

The quincunx fiber-optic network is designed as a HIPER-Ring with 100 Mbits and 58 switches and with interference tolerance, with the goal of ensuring continuous operation even in the event of a malfunction. The switches used are operational between -40°C and +70°C. To safeguard unused ports, they are equipped with “pro” firmware. As a result, unauthorized penetration of the network is not possible. The quality of service (QoS) of the switches provides the potential for giving preference to specific streams, specifically real-time information about approaching tram trains, for example, as opposed to video streams. The system is equipped with industrial Hivision software which makes it possible to monitor the proper operation of the network even without any knowledge of information technology. The analysis can be performed from all customer locations in the ring. This first loop is the “main artery” of the final complete network. The solution must provide the required quality of service without any restrictions. The use of VLAN (logic networks) is indispensable for this type of project to separate different streams.

Why Hirschmann?

  • Presence in the multi-service tramway network
  • Broad experience in this field
  • Adaptation of switches in their dimensions and to the environment
  • Customer-oriented service through our representative ETN