§ Mr. Nicholas Wintertonasked the Secretary of State for Transport, pursuant to his reply of 24 November, Official Report, column 71, why the design flow figure given of 91,000 vehicles per day for dual three-lane motorways differs from the figure of 85,000 vehicles per day given on 24 February, Official Report, column 501; and if he will make a statement.
§ Mr. Peter BottomleyThe design flows for dual three-lane motorways are specified in Department of Transport standards, which are revised from time to time. During the period when most of the M25 was being planned 85,000 vehicles was specified as the maximum design flow for 16 hours on an August day. The figure of 91,000 is the corresponding flow for a 24-hour August day. In the current Departmental standard, issued in November 1985, the flow is expressed as an annual average daily flow (24 hours) of 79,000. Allowing for seasonal variations in traffic volume this corresponds to the peak month figures mentioned above.