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produces traffic volume levels which are somewhat higher than at other times of the year. Currently, the peak hour volume on Austin Road adjacent to the site is about 120 two-way vehicles per hour while the two-way PM peak hour volumes on Arch Road and Mariposa Road west of Austin Road are 58 and 435 vehicles per hour respectively. All local roads are operating well under capacity with existing volumes. The present proportion of trucks in the traffic volume on Mariposa Road is approximately nine percent, based on recent afternoon peak hour classification counts taken for this analysis. Arch Road, just west of Austin, has approximately six percent trucks, and Austin Road has approximately five percent trucks north of Arch Road and 11 percent trucks south of Arch Road. For the purpose of this analysis, trucks are defined as motor vehicles with more than two axles or dual tires on at least one axle. Intersection aeration The projected summer 1988 peak hour traffic volumes at the two unsignalized intersections nearest the site have been analyzed based on the 1985 Highway Capacity Manual unsignalized intersection methodology. In this procedure, the side street STOP sign controlled turn movements and the left turn to the STOP sign controlled street are graded according to a scale called Level of Service (LOS) . This scale ranges from LOS A, indicating minimum congestion and delay, down to LOS F, indicating unacceptable delay for drivers. Level of Service C is often considered to be the worst service level which can be tolerated without mitigation measures to improve peak hour conditions. Some urban communities even use Level D or Level E for this criterion (see Table 3.1) . Both the Mariposa/Austin and Austin/Arch intersections have been analyzed for this study. Table 3.2 shows that with projected summer 1988 volumes, all turn movements at both intersections are operating at good levels of service (LOS A - little delay for turn movements), with the exception of the northbound left turn from Austin Road to Mariposa Road 3-25 101-32.R3 4/10/89