This report develops a modelling scheme within an urban traffic control (UTC) system so that its performance can be monitored on-line as part of its daily traffic operation. A review is given of the modelling techniques employed for off-line signal optimisation, on-line adaptive traffic control, and on-line performance monitoring. It suggests that a fruitful approach to on-line performance monitoring wou ld be to estimate platoon delays with a TRANSYT-like model within the framework of a control system such as SCATS. The accuracy of TRANSYT was then assessed by validation with floating-car survey data, and by a comparative study with the microscopic model NETSIM. The assessment confirms that TRANSYT modelling techniques would be appropriate for system monitoring. A scheme that makes use of the traffic flow profiles retrievable estimation, and a queue length/delay estimation procedure. This procedure models queue formation and dissipation at a stop line from the predicted arrival profile and the actual stop line departure profiles. The scheme was tested with simulated data, and with SCATS data collected in a field study. Both the queue lengths at the start of a green period, and the maximum back-of-queue that was formed as the head of a platoon joined the stationary queue at a stop line, were recorded. The results confirm the validity of the proposed scheme. The stop line flow profiles were also successfully utilized for automatic incident detection. Lane-by-lane queue length estimation was also found to be feasible. It is recommended that the scheme be employed in a control system for performance monitoring. A scenario of the future of adaptive UTC in the context of dynamic traffic management is also provided.

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  • Accession Number: 00495217
  • Record Type: Publication
  • ISBN: 0 86910 395 4
  • Report/Paper Numbers: SR 43
  • Files: TRIS
  • Created Date: Jul 31 1991 12:00AM