In this chapter the "capacity" of a transportation facility is defined as the maximum number of vehicles (or pedestrians) that can reasonably be expected to use the facility in a given time period under prevailing roadway, traffic, and control conditions. The concept of "level of service", first introduced in the 1965 Highway Capacity Manual, comprises a set of defined operating conditions for each facility type. The maximum amount of traffic that can be accommodated while maintaining the defined operating conditions is termed the "service volume" for that level of service. There are three primary activities that traffic engineering professionals perform and that depend on capacity and level of service analyses. First, when new facilities are being planned or when existing facilities are to be expanded, the size in terms of width or number of lanes must be determined. Second, when existing facilities are to be upgraded using traffic operational improvements or when it is desired to maintain or achieve a given level of service without resorting to capital intensive projects, the operational characteristics of the facility must be studied within the framework of level of service. Finally, it is becoming more common for the traffic engineering profession to contribute to economic and environmental analyses when considering public or private improvements. This study of operating conditions and level of service provides base values for road-user costs, fuel consumption, air pollutant emissions, and noise.
Samenvatting