international collaboration on research into strategies for area traffic control has led to the need for a common standard by which schemes tested in one country could be compared with those tested in another. representatives of the united states federal highway administration and the road research laboratory agreed that a suitable common basis for research in the united states and britain would be established by making comparative assessments, both in glasgow and in a us city, of transyt and its american counterpart, sigop, so that either could be used as a standard. this report describes the first part of the co-operative project, the assessment of sigop and transyt in glasgow. two forms of transyt were used, double-cycle transyt where minor intersections run on half the cycle-time of major intersections and single-cycle transyt where all signals in the area have a common cycle. during the mid-day and evening peak, with cycle times between 90 and 120 seconds, average journey-times were the same with sigop and single-cycle transyt. journey times with double-cycle transyt, as normally used in great britain, were 4 to 5 per cent quicker. morning peak results were difficult to interpret but it was probable that there was no difference between the three schemes during this period. a simulation based on the transyt model before the trial predicted differences of 5 to 7 per cent between sigop and double- cycle transyt. (a)

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