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- Technicnl Procedures I <br /> <br /> 7 LEVEL OF SERVICE METHODOLOGY FOR <br /> INTERSECTIONS <br /> <br /> Level of Service is the primary measure of effectiveness to be used in <br /> evaluating traffic operations at intersections on Basic Routes. All participating jurisdictions <br /> must use the adopted Level of Service methodology in developing their General Plan Growth <br /> Management Element, monitoring of Level of Service at Reporting Intersections, and preparing <br /> Traffic Impact Studies. If a jurisdiction elects to use another method for calculating Level of <br /> Service, it must be used in addition to the adopted methodology described in this section. <br /> <br /> Action Plans for Routes of Regional Significance may also include Level of <br /> Service as a quanti~able measure of effectiveness for Regional Routes. In these cases, the <br /> adopted Level of Service methodology shall also be used. <br /> <br /> The Level of Service methodology will be used to evaluate actual signalized <br /> intersection levels of service given traffic count data. It will also be used to evaluate future <br /> levels of service given traffic projections. The adopted method is similar to the Circular 2 12 <br /> Planning Method except that through movement capacity has been increased from 1,500 <br /> vehicles per hour to 1,800 vehicles per hour. Level of Service is calculated by critical <br /> movement with lower capacities assumed for turning movements. <br /> <br /> 7.1 SATURATION FLOW RATES <br /> <br /> The saturation flow rate is the basis for determining the capacity of an <br /> intersection. It represents the maximum number of vehicles that can pass through an <br /> intersection under prevailing traffic conditions. The CCTA has modified the Circular 2 12 <br /> Operations and Design Method by assuming a saturation flow rate of 1,800 vehicles per hour, <br /> (rather than 1,500 vehicles per hour). <br /> <br /> Saturation flow rates were measured at four intersections in Contra Costa <br /> County in February, 1990 to verify the appropriateness of this saturation flow rate. The <br /> method for collecting saturation flow rate data described in the 1985 Highway Capacity Manual <br /> was used. The results are summarized in Table 8. Considerable variation in saturation flow <br /> rates were observed at each intersection. The data suggested that the operations and design <br /> capacities based on the 1,800 vehicles per hour saturation flow rate are frequently achieved <br /> within Contra Costa County. <br /> <br />-- I <br /> <br /> <br />