Since 1994 the Traffic Director for London has funded a series of innovative studies to investigate the benefits from using existing signal control 'strategies' in traffic situations that they were not originally designed to address. The studies have been carried out on a 6-km section of the A12, an arterial road in the eastern suburbs of London, containing six traffic signal junctions. In the previous study, the effectiveness of the MOVA strategy for isolated junction control was compared to the use of TRANSYT fixed-time plans. Significant benefits were found from switching between strategies as were reported in the January 1996 issue of this journal. In a more recent study, MOVA has been compared with the SCOOT strategy, which is used worldwide for co-ordinated adaptive control. The delay savings varied between junctions, with some giving smaller delays with SCOOT and some with MOVA. Selecting the best strategy for each junction at each time of day does give benefits. A best estimate of the average value of these is £170 000 per annum, of which E126 000 is statistically significant, against the cost of installing SCOOT of £150 000. This could be improved by changing strategy at the correct point for the current conditions, rather than for a manually-defined time period and so, as the next part of this series of studies, the Traffic Director for London is now implementing a real-time strategy selection system that is also described in this paper. This strategy selection system will provide the network manager with real-time information on the effect on traffic of the current and alternative signal control 'strategies'. It will use specifications developed in the Department of the Environment, Transport and the Regions' Urban Traffic Management and Control (UTMC) research programme, to build on these existing results within a comprehensive research and development framework.
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