Highways Agency Reports

TRL have been commissioned by the Network Policy Division of the Highways Agency to monitor network performance on the motorway and all purpose trunk road network in England. The congestion indicator currently used for monitoring network performance is the eight hour indicator, defined as the proportion of the network which is congested for more than eight hours per week. Other indicators have been suggested for monitoring congestion for different purposes. These include vehicle hours delays, kilometre-hours and hours congested. This report defines these indicators and reviews their advantage and disadvantages, including the practical problems of obtaining the data required for their estimation.