A METHOD OF ASSESSMENT OF DELAYS CAUSED BY ROADWORKS

Roadworks inevitably cause delays to traffic and these are rarely evaluated. As part of the economic assessment of a road improvement scheme, a method of measuring these delays was derived. A model was built that reflected the unrestricted situation in terms of traffic flows and travel time, and the total travel costs were worked out. The model was then changed to represent the effects of major roadworks on the link in question and the total costs re-evaluated; the two costs were then compared to give disbenefits. The model uses deterministic principles and takes account of a balance of traffic volumes queueing on the main route and those that divert. The model was run for the "do-nothing" and "proposed scheme" situations and the difference in the disbenefits assumed as an economic benefit of building the proposed scheme. The benefits calculated constituted over 50 per cent of the total benefits of the scheme.(a) (TRRL)