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GEOMATRIX Structural design of flexible pavements is based on the strength of the subgrade soil, strength of the pavement materials, and assessment of vehicle traffic (both vehicle weight and frequency). The Caltrans method ofavement design uses the R-value test to evaluate the P g strength of subgrade soils and pavement materials. A representative sample of the near surface site soils was collected while drilling the boring at the pump station site. An-R-value of 27 was obtained from the one test performed on the near-surface soils; a R-value of 20 was conservatively assumed for design of asphalt pavements.. The Caltrans method uses the Traffic Index (T.I.) to designate the volume of traffic and weight of vehicles expected to travel on roadway and parking areas. The T.I. is based on estimated traffic volumes projected over the economic life of.the pavement(usually 20 years) and the expected mix of cars and trucks. Based on discussions with KJC,traffic index values of 5, 5'/2 , and 6 were selected for the design of representative pavement sections. Parking areas used primarily by lightweight vehicles (i.e., automobiles and pickup trucks) typically are designed for a T.I. of at least 5. The entrance to the parking areas and areas subject to truck traffic are typically designed for a T.I. of 6 or more. The following structural pavement sections have been prepared for the estimated traffic indices. Pavement Component Thickness (feet) Traffic Index (T.I.) Asphalt Concrete Aggregate Base 5 0.25 0.65 5% 0.30 0.75 6 0.30 0.85 The pavement material should conform to the following sections of the City of Tracy Standard Specifications which, in turn, refers to the SPPW. Section of Pavement Material Type of Material Standard Specifications Asphalt Concrete Class C1-AR-8000 203-6 Aggregate Base Crushed Aggregate Base 200-2.2 The subgrade soil should be compacted to a minimum of 95 percent at a moisture content at I least 1 percent above optimum. The aggregate base material also should be compacted to a minimum of 95 percent. 1:1Proj ect15000s153131LE W 1S-MAN.DOC 12 I� r