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Once classified, the urban street is divided into segments for analysis. An urban street segment is a one-way section of street encompassing a series of blocks or links terminating at a signalized intersection. Adjacent segments of urban streeu may be combined to form larger street sections, provided that the segments have similar demand flows and characteristics. Levels of service are related to the average travel speed of vehicles along the urban street segment or section. Travel times for existing conditions are obtained by field measurements. The maximum-car technique is used. The vehicle is driven at the posted speed limit unless impeded by actual traffic conditions. In the maximum-car technique, a safe level of vehicular operation is maintained by observing proper following distances and by changing speeds at reasonable rates of acceleration and deceleration. The maximum- car technique provides the best base for meazuring traffiic performance. An observer records the travel time and locations and duration of delay. The beginning and ending points are the centers of intersections. Delays include times waiting in queues at signalized intersections. The travel speed is determined by dividing the length of the segment by the travel time. Once the travel speed on the arterial is determined, the LOS is found by comparing the speed to the criteria in Table A-IV. LOS criteria vary for the different classifications of urban street, reflecting differences in driver expectations. Table A-11: Functional and Design Categories for Urban Streets C it i Functional Category r er on Principal Arterial Minor Arterial Mobility function Very important Important Access function Very minor Substantial Points connected Freeways, important activity centers, major Principal arterials traffic generators Relatively long trips between major points Trips of moderate length within relatively Predominant trips served and through trips entering, leaving, and small geographical areaz passing through city Crit ion Design Category er Hlgh-Speed Su6ur6an Intermediate Urhon Driveway access density Very low density Low density Moderate density High density Multilane divided; Multilane divided: Multilane divided or Undivided one Arterial type undivided or two- undivided or two- lane with undivided; one way, way; two way, two lane with shoulders shoulders two lane or more lanes Parking No No Some Usually Separate lek-wrn lanes Yes Yes Usually Some Signals per mile 0.5 to 2 Ito 5 4 to 10 6 to 12 Speed limits 45 to 55 mph 40 co 45 mph 30 to 40 mph 25 to 35 mph Pedestrian aaiviry Very little Little Some Usually Roadside development Low density Low to medium Medium to High density density moderate density Source: Highway Capacdy Manuo12000