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Traffic Flows

Volume 264: debated on Thursday 19 October 1995

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To ask the Secretary of State for Scotland what is the legal upper limit for the daily flow of traffic on single carriageways in Scotland. [36409]

There is no legal limit to the level of traffic flow on a single carriageway. Capacity of a road can be influenced by factors such as the quality of the road, the percentage of heavy goods vehicles or how hilly the road is. Research by the Transport Research Laboratory suggests that the maximum sustainable two-way flow for a high-quality standard single carriageway could range between annual average daily traffic flows of 14,000 to 19,000 with 0 to 30 per cent. HGVs and 21,000 to 28,000 for a similar wide single carriageway with the same range of HGVs. These figures inform the design guidance on which the assessment of new roads is based.