The Effects of Wheel Clamps in Central London: Comparison of Before and After Studies.

Abstract

This Report compares the results of the Before and After studies of some effects of the introduction of wheel clamps in Central London. Park and Visit and Vehicle Following studies were carried out in both cases, with Registration Number and Business Interview surveys taking place in the Before study only. The two areas of Central London which were studied comprised an area of Mayfair in which wheel clamps were to be introduced, and an area of Bloomsbury in which they were not. The surveys were designed to identify changes related to congestion and ease of access effects and so complement a series of surveys conducted by consultants for TRRL. The report describes each survey methodology, and presents the results of the Park and Visit and Vehicle Following surveys. A significant reduction in journey times is identified in Bloomsbury but not in Mayfair. However, the confidence intervals for Mayfair were too wide to determine whether the change in travel times in Bloomsbury was significantly different from the change in Mayfair. Significant reductions in search time are recorded in both areas, and a significant reduction in search plus walk time in Bloomsbury. An increase in empty meter spaces is identified in Mayfair and these findings from the Park and Visit surveys are supported by evidence from the Vehicle Following survey which suggests a drop in the degree of searching for meter spaces in Mayfair. Note: Further details of the survey are to be found in the associated technical note to this report (May et al, 1984b) and the individual reports on the Park and Visit and Vehicle Following surveys (May et al, 1984a)