TRL and John Fearon Consultancy have been commissioned by ITEA Division of the DfT to review and update the parameters used in the INCA (INcident Cost-benefit Assessment) economic evaluation software. INCA is used in the economic assessment of the effect of road schemes on the delay and journey time variability associated with incidents. This Working Paper is concerned with extending the INCA methodology to all-purpose (AP) roads and in particular with validating the default INCA parameters. Incidents are defined as being unexpected events that physically affect the number of lanes available for traffic. They are classified into a number of types, including accidents (single and multi-lane), breakdowns, debris, major fires, load shedding, spillage and animals. Unplanned emergency roadworks may also be classified as an incident. (Author/publisher)
Abstract