HC Deb 15 January 1997 vol 288 cc243-4W
Mr. Chidgey

To ask the Secretary of State for Transport if the road damage calculations quoted in the recent consultation document, "Lorry Weights", are based upon static conditions on a level surface; and what estimates have been made of road damage characteristics associated with typical dynamic conditions taking account of speed, uneven road surfaces and the variable quality of vehicle suspensions. [10906]

Mr. Watts

The dynamic effect of a given axle weight is dependent upon a number of factors including road surface, axle spacing, tyre and suspension type. The fourth power rule was derived from a series of dynamic tests in which different types of lorries were run repetitively over sections of road surface. The best approximation between road wear and lorry weight was found to be the fourth power of the static axle load.

Further work has been carried out in Germany and at the Transport Research Laboratory to take greater account of vehicle suspension and road types. But these effects are relatively small and static axle load remains the dominant factor. The TRL is currently participating in a European programme to determine the road wear effects of different tyre types.

Mr. Chidgey

To ask the Secretary of State for Transport what provisions there are to seek an extension of the derogation from EC directive 96/53 admitting 40-tonne lorries to Britain; and what plans he has to do so. [10904]

Mr. Watts

None. Under the terms of the original directive, 85/3/EEC now consolidated as 96/53/EEC, the United Kingdom would have been obliged to accept 40-tonne lorries on international journeys from July 1986. The Government negotiated a derogation from this requirement which expires on 1 January 1999.

Mr. Chidgey

To ask the Secretary of State for Transport what assessment he has had made of how much greater damage will be caused by the drive axles of 40-tonne lorries to road pavements when fully laden than is caused by 38-tonne lorries. [10905]

Mr. Watts

The 11.5 tonne axle weight of 40-tonne lorries would cause about 45 per cent. more road wear than the 10.5 tonne drive axle weight of 38-tonne vehicles, assuming in both cases that the axles are fully laden.