§ Mr. Buchanan-Smithasked the Secretary of State for Scotland what level of traffic density justifies the incorporation of a dual carriageway when a new road is constructed; and whether the type of vehicles as well as the number is taken into account.
§ Mr. McElhoneThe upper and lower design flow figures necessary to justify the construction of a dual carriageway, expressed in terms of 16-hour average daily flow for the month in which the heaviest traffic occurs, are as follows:
TYPE OF ROAD AND NUMBER OF VEHICLES PER 16-HOUR DAY Dual 2-lane all-purpose with 7.3 metre wide carriageways 45,000–17,000 Dual 3-lane all-purpose with 11.0 metre wide carriageways 60,000–35,000 The recommended flows allow for a proportion of heavy vehicles equal to 15 per cent. The maximum figures could be reduced, possibly substantially, depending
222Wminating or breaking its journey in Stonehaven is not available.
upon the flow characteristics of a particular road.