Abstract
A single short period count is undertaken when an estimate of traffic flow is required at a specific site. This is done for ad hoc studies, such as the investigation of a highway proposal. Such a count is needed, for example, for the economic evaluation of road schemes using the department of transport's computer program COBA. In this report, the efficiency and accuracy of annual flow estimates from short period counts are examined. Recommendations are given for the most appropriate length and timing of counts. These consist of values for the expansion factors used to estimate annual flow, and measures of the accuracy of these estimates. (Author/publisher)