This study collated all the readily available information from fully operational road tunnels throughout the United Kingdom of length greater than 150 metres. Seven of these were subaqueous crossings. Data were collected between October 1983 and September 1984 during visits to all the tunnels considered in the report; available records and the physical installations were examined and additional information obtained from tunnel personnel. In many cases further information was available from published sources and from the firms of consulting engineers responsible for the design and construction of the tunnels. The results were summarised in tabulated form. There were very strong correlations between the two lane kilometre length of tunnel and the total operating cost, which in turn was a function of the staffing complement and complexity of the operation. The interdependence of physical features, operating standards and costs was a complex relationship between the nature of the tunnel and the policy of the operation. This was complicated further by a consideration of environmental standards and benefits produced by the tunnel. Even when a cost-benefit analysis alone did not favour tunnel construction the increased environmental benefits might prove sufficient grounds for the selection of a tunnel option.

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