ESBGU <br />The following design parameters were assumed for AC design: <br />reliability of 90% <br /> <br />internal serviceability of 4.2 <br /> <br />terminal serviceability of 2.5 <br /> <br />overall standard deviation of 0.5 <br /> <br />subgrade resilient modulus, M, of 4,500 psi <br /> <br />r <br />base aggregate resilient modulus, M, of 20,000 psi <br /> <br />r <br />30-year design <br /> <br />For our analyses, we assumed an ADT of 234 bussesbased on a bus turnover rate <br />of one bus every ten minutes for each of the six bays for 6.5 hours each day. The <br />design ESALs for both pavement designs (rigid and flexible) were calculated using <br />the ADT, the pavement specific design life, and the annual ESAL factors. For <br />busses, the City of Eugene Public Improvement Design Standards Manual (2016) <br />specifies an annual ESAL factors of 1390 for rigid pavements and 960 for flexible <br />pavements. Based on these values, we calculated ±13,011,000 ESALs for the rigid <br />pavement design and ±6,528,600 ESALs for flexible pavement design. The design <br />ESALs assume no annual growth. <br />The ESAL factors prescribed by the City appear to correlate to fully-loaded busses. <br />We anticipate this is a conservative assumption because many of the busses will be <br />empty or partially loaded. The results of our analyses indicate the Bus Loop <br />pavement should consist of either: <br />a minimum of 11 inches of PCCover 12inches of Base Aggregate <br /> <br />a minimum of 8 inches of AC over 26 inches of Base Aggregate <br /> <br /> The passenger vehicle parking lot will be paved with <br />AC. We anticipate the traffic will include predominantly light passenger vehicles. <br />We have assumed no bus traffic will be allowed in this area. Based on the limited <br />traffic, we recommend using a nominal flexible pavement section of 3 inches of AC <br />over 12 inches of Base Aggregate. <br />. We anticipate the traffic in the drop off areaand <br />driveway on the east side of the site will include the addition of occasional truck <br />traffic (e.g. maintenance vehicles, garbage and recycling trucks, and delivery <br />trucks). For this area we recommend increasing the flexible pavement section to <br />4 inches of AC over 12 inches of Base Aggregate. The pavement section for the <br />driveway should be re-evaluated if additional traffic is expected following the <br />development of the northern portion of the lot. <br />Santa Clara Transit Center January 15, 2019 <br />Geotechnical Investigation 6 Project 2181060 <br />Eugene, Oregon Rowell Brokaw <br />