during july 1972, the transport and road research laboratory undertook a study of the effects on traffic of surface-dressing work on trunk road a2 in kent. a number of methods of traffic control were used during the study, each of which restricted the traffic stream in one direction to a single lane. for each of the traffic control schemes, the traffic delays and capacity of the site were measured. the merge on the approach to the single lane section appeared to limit the traffic throughput with the result that no appreciable differences in the performances of the traffic control schemes were observed. on each day of the study, during the periods of peak traffic flow, long queues of traffic built up on the approaches to the site, with the result that the traffic delays over the five days of the study amounted to 17 300 vehicle-hours. a method of traffic control is described which would have reduced the delays by a factor of 10 by maintaining two lanes of traffic in each direction. the results of the traffic flow observations suggested that the maximum throughput of traffic which could be obtained when a queue of vehicles was present on the approach to the site was 10 per cent less than the maximum achieved when the system was flowing freely.(a)

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