M25 Managed Motorways J16 - Highways Agency

4.1 Do Nothing Baseline ie ExistingThe Do-Nothing Baseline, or existing situation, is a dual four lane carriageway tomotorway standard (D4M) with the MIDAS system (Motorway Incident Detection andAutomatic Settings). MIDAS is a system comprising of inductive loops buried in thecarriageway surface which detect the presence of stationary or slow moving traffic. Thisinformation is transmitted to computers which will then provide written warnings andadvisory speed limits upstream of the congestion event. The warnings and advisoryspeed limits are provided via variable message signs which are mounted oncantilevered mast arms above the carriageway. The purpose of the system is tominimise the risk of collisions between fast moving upstream traffic and the slow movingor stationary traffic detected by the loops.23