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APPENDIX A LEVEL OF SERVICE The description and procedures for calculating capacity and level of service (LOS) are found in Transportation Research Board, Highway Capacity Manual 2000. Highway Capacity Manual 2000 represenu the latest research on capacity and quality of service for transportation facilities. Quality of service requires quantitative measures to characterize operational conditions within a traffic stream. LOS 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 of service are defined for each type of facility that has analysis procedures available. Letters designate each level, from A to F, with LOS A representing the best operating conditions and LOS F the worst. Each LOS represents a range of operating conditions and the driver's perception of these conditions. Safety is not included in the measures that establish service levels. A general description of service levels for various types of facilities is shown in Table A-I Table A-1: Level of Service Description Uninterrupted Flow Intercupted Flow Facility Type Freeways Multi-lane Highways Two-lane Highways Urban Sweets Signalized Intersections Unsignalized Intersettions Two-way Stop Control All-vrey Stop Control LOS A Free-flow Very low delay. B Stable Flow. Presence of other users noticeable. Low delay. C Stable Flow. Comfort and convenience starts to decline. Acceptable delay. D High-density sable flow. Tolerable delay. E Unstable flow. Limit of acceptable delay. F Forced or breakdown Clow. Unacceptable delay Source: Highway Capacity Manua12000 Urban Streets The term "urban streeu" refers to urban arterials and collectors, including those in downtown areas. Arterial streeu are roads that primarily serve longer through trips. However, providing access to abutting commercial and residential land uses is also an important function of arterials. Collector streets provide both land access and traffic circulation within residential, commercial and industrial areas. Their access function is more important than that of arterials, and unlike arterials their operation is not always dominated by traffic signals. Downtown streeu are signalized facilities that often resemble arterials. They not only move through traffic but also provide access to local businesses for passenger cars, transit buses, and trucks.