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The Ramp Metering controller releases cars onto the motorway based on the volume of traffic reaching the on-ramp. This avoids the inevitable slowing of motorway traffic that occurs around motorway entrances. Based on our ATSC4 Traffic Signal Controller, the Ramp Metering unit controls 1 or 2 sets of signals on a ramp joining a high speed motorway. The Ramp Metering Controller allows 1 green signal per lane at a time to minimise delays on the motorway due to the joining vehicles being slower than the motorway vehicles.
The Ramp Metering controller must be connected to a SCATS® Adaptive coordination system that also informs the Ramp Metering controller of when it is best to release vehicles onto the motorway. By controlling the number and timing of vehicles joining the motorway, traffic congestion can be minimised. The algorithms and set up of the ATSC4 Traffic Signal Controller as well as the setup within SCATS® must be well coordinated for the algorithms that measure the release of traffic onto a motorway are very different to those needed for coordination. Improper implementation of ramp metering may solve one issue of how best to "release" traffic onto a motorway but may cause a bank-up of traffic on the arterial roads that feed the on-ramp to the motorway.
ATC can provide specialist design and implementation consultancy on deploying these systems, especially where motorways are adjacent to heavily built up arterial roads in urban areas. For more information on implementing a Ramp Metering solution, please contact us.