The Summit 18 Corridor Study will consider Levels of Service (LOS) throughout the study corridor as one means of identifying problem locations for improvement. LOS is a rating that basically refers to the ability of a roadway segment, interchange ramp or intersection to efficiently carry current (2006) or future (design year 2030) traffic volumes. Similar to a report card grading system, LOS ratings (shown below) vary from A to F with LOS A indicating efficient traffic movement with no congestion and LOS E and LOS F indicating service at or near failure with substantial congestion and travel delay.
LOS A
Represents the best operating conditions and is considered free flow. Individual users are virtually unaffected by the presence of others in the traffic stream.
LOS B
Represents reasonably free-flowing conditions but with some influence by others.
LOS C
Represents a constrained constant flow below speed limits, with additional attention required by the drivers to maintain safe operations. Comfort and convenience levels of the driver decline noticeably.
LOS D
Represents traffic operations approaching unstable flow with high passing demand and passing capacity near zero, characterized by drivers being severely restricted in maneuverability.
LOS E
Represents unstable flow near capacity. LOS E often changes to LOS F very quickly because of disturbances (road conditions, accidents, etc.) in traffic flow.
LOS F
Represents the worst conditions with heavily congested flow and traffic demand exceeding capacity, characterized by stop-and-go waves, poor travel time, low comfort and convenience, and increased accident exposure.
