Abstract
This report is intended to indicate some of the difficulties which are likely to be encountered in survey studies of urban bus services, when the objective is to measure the changes in passenger waiting times which are brought about by an operational change. Methods of determining waiting times that have been used in previous work, and their limitations, are described. The day to day variability of bus operations, which acts as a source of 'random errors' in such work, is illustrated by measurements from surveys carried out by TRRL and London transport. (Author/publisher)