The software products used to monitor the performance of the Controlled Motorway Scheme between Junctions 10 and 16 of the M25 motorway, UK, are described. The scheme is an automated variable speed limit system developed by the Highways Agency. It operates using the Motorway Incident Detection and Automatic Signalling (MIDAS) system. The controlled section has looped detectors buried under the road every 500m to collect real-time traffic data. Signal gantries automatically display mandatory speed limits in response to the MIDAS traffic data and limits are enforced using speed detector cameras. TRL has monitored the scheme since 1995. Details are given of TRL's role as operational technology support body for the scheme. The Motorway Traffic Viewer (MTV), the traffic analysis tool developed by TRL, is described. MTV is used to plot the whole stretch of the carriageway. It is a data visualisation tool that uses a database that contains information on the location of MIDAS loops, junctions and signal gantries along the motorway. MIDAS Health Check (MIDAS HC) is a graphical tool used to determine how well the MIDAS loops are functioning and to help in the diagnoses of MIDAS loop faults.
Abstract