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I I 4.8 PAVEMENT RECOMMENDATIONS <br />4.8.1 General <br />The pavement design analyses were completed using the design methodology outlined in the <br />1993 AASHTO Guide for Design of Pavement Structures (AASHTO Guide). The traffic loading <br />information was assumed as summarized below: <br />• Average daily traffic (ADT) <br />• 75 trucks — about 50 residential route trucks and 25 semi -trucks, and <br />(' • 360 one-way trips for a Cat 980 front-end loader (3 minute cycle time over 9 hours) <br />• Percent growth of 2 percent for next 20 years <br />• 100 percent trucks or front end loaders in the design lane <br />• Traffic occurs 5 days per week <br />i <br />In our pavement design analyses, we assumed the following: <br />• 20-year dep;-; life <br />• Reliability or . ) percent <br />• Initial serviceabilit- rf4.2 <br />• Terminal serviceability of 2 <br />• Overall standard deviation of 0.45 <br />• Truck load factor of 20 for a CAT 980 front-end loader <br />• California Bearing Ratio (CBR) for suhgmde soils of 2, which corresponds approximately to a <br />resilient modulus of 3,000 pounds per square inch (psi) <br />Using the information presented above we developed pavement recommendations for 32.1 million <br />18-kip equivalent single axle loads (ESALs). <br />4.8.2 Asphalt Concrete Pavement <br />Using the input parameters described above and the methodology presented in the AASHTO Guide, <br />we recommend the alternative asphalt concrete pavement sections presented in Tables 3 and 4 be <br />considered for the project. <br />Table 3. Recommend Asphalt Concrete Pavement Sections (front-end loader traffic areas) <br />I <br />1,1111111111.111 <br />e d - cltiiess�x�� <br />Jr. � ", aterial <br />M.Wen <br />70 , � <br />QP,T(O. , <br />, , ,_ TfO,. � <br />r.,nr�+:.OPTlON44?�,1; <br />Ad, Class B <br />ATBr <br />5 <br />4 <br />I 3 <br />1 5 <br />I 4 <br />& <br />CSBC' <br />15 <br />I <br />I 3 <br />Tensar BX1100 <br />Geogrid <br />No <br />No <br />i Yes <br />No <br />Sand/GravelSubbase <br />23 <br />j 23 <br />12 <br />1 12 <br />TensarBX1200 <br />Geogrid <br />No <br />No <br />Yes <br />Yes <br />'AC = As halt Concrete Pavement, Class B per WSDOT Specifications 5-04 and 9.03. <br />=ATB = Asphalt Treated Base, per WSDOT Specifications 4-06 and 9-03. <br />'CSBC = Crushed Surfacing Base Course, per WSDOT Specifications 9-03.9(3). <br />G e 0 E n g i n e e r s 21 Pile No. 10625-001-02/123003 <br />