The speed of travel for through movements on urban streets where traffic flow is interrupted due to the presence of signals can be estimated using the speed-flow curves in the Highway Capacity Manual, as a function of signal density and intersection volume-capacity (v/c) ratios. Figure 5.3 shows one such speed-flow curve for class II urban streets. The signal timing and street design assumptions used in developing these curves are provided in the footnotes. Similar curves for different sets of assumptions and classes of urban streets available in the Highway Capacity Manual can be used to determine the average speed at such section as a function of signal density. For example, using Figure 5.3, the travel speed on a 6-mile urban street with three isolated signalized intersections per mile and peak direction v/c ratio of 0.6 is approximately 20 mph.