LABOUR-SAVING METHODS FOR COUNTING TRAFFIC MOVEMENTS AT THREE- AND FOUR-ARM JUNCTIONS

In order to obtain an automatic count of vehicles making specific turning movements off a highway, observers are usually employed to record the route that each vehicle takes. The article describes a method of obtaining a traffic count by the suitable placing of automatic counters so that the number of observers can be reduced. It is shown that by choice of option and use of local knowledge or historic information, good estimates or even 100% accurate results can be obtained without using one observer per arm of a junction. /TRRL/