Existing Traffic Conditions


One of the study tasks is to provide a snapshot of existing traffic conditions throughout Boone County. Roads that were considered in this analysis include all interstates, U.S. routes, state routes, plus key County-maintained roads. Information on road geometry, functional classification, traffic control, posted speed limits, and daily traffic volumes was obtained from the Kentucky Transportation Cabinet and Boone County.


Level of Service


A Level of Service (LOS) analysis was performed to provide a description of typical morning and evening peak hour traffic conditions on key streets and roads throughout the county. Level of Service[1] is a quality measure describing operational conditions within a traffic stream, generally in terms of such service measures as speed and travel time, freedom to maneuver, traffic interruptions, and comfort and convenience. Six levels are defined. Letters designate each level, from A to F, with LOS A representing the best operating conditions and LOS F the worst. Traditionally, a facility is considered to have reached capacity at LOS E. Each level of service represents a range of operating conditions and the driver's perception of those conditions. Safety is not included in the measures that establish service levels.


Level of service measures vary, depending on facility type. For interstates and divided highways, LOS is determined as a function of density; that is, the number of vehicles per lane per mile of roadway. For arterial streets, LOS determination is based on the average travel speed of the vehicles traveling the defined section. At intersections, both signalized and unsignalized, LOS is a function of delay. For two-lane highways, level of service is determined according to two measures percent time spent following (which represents the freedom to maneuver and the comfort and convenience of travel) and average travel speed.


LOS methods can be applied at varying levels of complexity planning, design and operations. In a planning application such as the Boone County Transportation Study, the analysis is used to answer a fundamental question: Does a particular road have sufficient through-lane capacity to adequately serve the demand?


[1] Source: 2000 Highway Capacity Manual, Transportation Research Board, National Academy of Science, Washington, D.C.