In 1997, in response to growing concern about the problem of inappropriate speed and its contribution to child pedestrian accidents, The Society of Chief Officers of Transportation in Scotland (SCOTS), invited Scottish Local Authorities to participate in a national trial programme of advisory 20mph speed limits in residential areas. Site selection criteria were issued, and 27 Councils submitted sites for consideration in the programme, with a total of 75 individual sites being accepted for inclusion in the trial. In order to monitor and evaluate the operation and outcome of the trial The Scottish Executive and SCOTS commissioned Halcrow Fox to conduct a three-year programme of research. The research assessed the impact of these trial 20mph speed limits, some 18-24 months after the initial installation, considering limited data from all 75 trial sites, and intensive data from 8 sample sites. The primary aim of the study was: “to monitor and evaluate the operation and outcome of the 20mph trial zones in order that conclusions can be drawn on their effectiveness and whether the scheme should be extended. A central aim therefore is to establish whether the trial zones are meeting their objectives”. This involved the consideration of quantitative measures of impact (vehicle speeds, flows and accidents) and also the attitudes and perceptions of the local community to the scheme, and to the process of implementation. The aim emphasised the need for the survey to capture a wide range of trial projects so that robust conclusions can be drawn about the merits (or demerits) of the scheme. This will allowed meaningful guidance on the implementation of 20mph speed limits without engineering measures to be developed.
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