Queue Delay Surveys
Queue delay surveys involve the notation of sample vehicle arrival times at an intersection, and then their departure times, as they cross the stop line on the green phase. A variety of techniques can be used to collect queue delay data; generally a manual observation technique is used. In a single cycle, a single observer may track a number of sample vehicles.
Global positioning systems can also be useful tools in obtaining delay data as part of in-car travel time surveys. Operator identifiers can be added to indicate the joining of a queue, but the lack of movement detected by the GPS can also reasonably demonstrate queue formation.
Queue Length Surveys
A typical queue length survey involves recording the number of vehicles in a queue just prior to the red signal changing to green for one or more legs of an intersection. When there are multiple lanes, the number of vehicles in the longest queue only, or in each lane separately, can be recorded.
Another variation is to have pre-set distance makers and record the times at which the queue meets that marker.
In situations where queues do not clear within a single traffic signal phase, the volume of vehicles remaining at the start of the new red phase can be collected.