RAMP METERING SYSTEMS, North Rhine-Westphalia, Germany

, 2001 - 2010


The signal light installation of the ramp metering system is switched off as long as the traffic flows unhindered on the main road. Measurement loops monitor the traffic flow. As soon as the traffic density reaches a threshold value, ramp metering and signal light installation are activated.

Algorithms calculate from the current traffic data the optimal parameters for the signal head control. The time for the "red phases" for the oncoming traffic is regulated according to traffic density.

In order to avoid greater disturbances on the main lane of the motorway, only one vehicle at a time is allowed to pass the ramp metering installation during the green phase. This is realised by a fast reaction upon loop impulse and by short yellow phases.

Project Content

  • 95 Ramp metering installations
  • 129 Road stations
  • Measurement cross-sections with inductive loops on motorway and ramps
  • 54 Prism openers on the accessing roads, partly controlled via radio signals


These ramp metering systems were started in 2001.
Up to now, only the kind of ramp metering systems has been installed in Germany which are according to TLS 2002 standard.
The project ramp metering systems is continuously being extended.


  • Improvement of traffic flow
  • Reduction of congestions and accidents
  • Increase of average speed in dense traffic
  • Better use of motorway capacity