Existing Traffic
Conditions
One of the study tasks is
to provide a snapshot of existing traffic conditions throughout
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,