§ Mr. LansleyTo ask the Secretary of State for the Environment, Transport and the Regions what are his latest estimates of the degree of over-capacity usage of the A14 between Huntingdon and Cambridge. [55429]
§ Ms Glenda Jackson[holding answer 19 October 1998]: A number of factors govern the absolute capacity of a road, including the spread of peak hour usage throughout the day and the proportion of the traffic flow that is composed of heavy commercial vehicles. A measure of capacity has been produced which is called the congestion reference flow (CRF). The CRF of a section of road is estimated of the 24 hour Annual Average Daily Traffic flow (AADT = total annual traffic divided by 365) at which the carriageway is likely to be "congested" in 1097W the peak periods of the average day. The CRF for the dual-two lane section of the A14 between Huntingdon and Cambridge has been calculated as 78,371 vehicles per day (vpd). Current average traffic flows on this section of road are up to 68,000 vpd (87% of the CRF). Traffic flows on this section of A14 are high, therefore, but not beyond its capacity in terms of the road's calculated CRF.