§ Mr. David Young
asked the Secretary of State for Transport what was the traffic density and weight density which each motorway in the United Kingdom was designed to carry; how much was actually carried; what was the spare capacity, if any; what his timetable for the future is; and if he will make a statement.
§ Mr. Kenneth Clarke
It is not possible to give the actual design figures used or to say how much traffic has been carried by each and every section of motorway in the country without unjustified expenditure and use of resources.
Before 1974 the number of carriageway lanes was based on the flow of vehicles expected to be using the road 15 years after opening to traffic. After 1974 the design flows were increased to take account of actual experience.
Up to 1970 the design of motorway pavements in the United Kingdom was based on the number of commercial vehicles over 30 cwt. expected to use the road each day 20 years after opening to traffic. After 1970 the design was altered to consider the cumulative traffic load of these vehicles on the near-side lane in one direction during the design life of the road, which was 20 years for bituminous paving and 40 years for concrete pavings.
Actual flows on motorways are published in "Transport Statistics, Great Britain". Fotunately, many miles of motorways have successfully carried much more than the traffic loads and flows for which they were designed.
Our proposals for the future are set out in "Policy for Roads in England—1980"—Cmnd. 7908.