Level of Service

Level of service is a measure by which transportation planners determine the quality of service on transportation devices, or transportation infrastructure. Whilst the motorist is, in general, interested in speed of his journey, LOS is a more holistic approach, taking into account several other factors. As a result LOS is regarded a measure of traffic density (or a measure of congestion), rather than overall speed, of the journey. It is however it is closely linked to transportation time (the shorter, the better). Level of service may be used for other public facilities as a tool to measure changes in condition or availability, such as water supply.
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1) A set of characteristics that indicate the quality and quantity of transportation service provided, including characteristics that are quantifiable and those that are difficult to quantify. 2) For highway systems, a qualitative rating of the effectiveness of a highway or highway facility in serving traffic, in terms of operating conditions. 3) For paratransit, a variety of measures meant to denote the quality of service provided, generally in terms of total travel time or a specific component of total travel time. 4) For pedestrians, sets of area occupancy classifications to connect the design of pedestrian facilities with levels of service. (TRB1)