§ Mr. Russell
asked the Secretary of State for Scotland why Tunnel No. 1 under the River Clyde at Glasgow is costing nearly double the amount estimated at the time its construction was authorised.
§ Mr. Maclay
The estimated cost of building Tunnel No. 1, on which a limited scheme was authorised early in 1955, was a preliminary one based on outline information only. The amount of the accepted tender, which forms the basis of the cost of the scheme as it is being undertaken, was decided some two and a half years later after much detailed investigation of the problems involved. The difference reflects the technical development of the scheme, the difficulties encountered and the movement in costs of materials and labour in the intervening period.