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The AM and PM peak hour Level of Service analysis projected that this intersection would operate at LOS "A" under both future plus project conditions with the assumed intersection approach geometries and intersection control. Warrants provided in Exhibit 9-75, Guide for Left-Tum Lanes on Two-Lane Highways, published in the American Association of State Highway and Transportation Officials (AASHTO)publication A Policy on Geometric Design of Highways and Streets, 2004 was used to determine if a northbound Koster Road left tum lane would be warranted at this intersection. A comparison of the volume warrants shown in Exhibit — 9-75 with the AM and PM peak hour volumes project for the year 2027 plus project traffic condition shows that provision of this left turn lane would not be warranted. ROADWAY TRAFFIC INDEX (TI) VALUES Traffic Index (TI) is a numerical measure of the ability of a road structure to carry truck loads. It is — determined by calculating the number of equivalent single axle loads (ESAL) of 18,000 pounds that will travel the road in one lane over the design time period. For this analysis, both a 10-year and a 20-year design period is used for calculating TI's. The Caltrans method of calculating TI described in their — "Highway Design Manual" was used as the basis after determining the ESAL. A review of the "Bird Road Improvement Plans" (1997) indicated that a TI value of 8.5 was used in _ designing the structural section along southbound Bird Road, and a TI value of 10.5 was used in designing the structural section along northbound Bird Road. The lower Tl value was used for southbound Bird Road because the majority of trucks are traveling empty in this direction and are significantly lighter than the loaded northbound Bird Road trucks. A review of the County's "Road Inventory" indicated that Koster Road is built on six-inches of base material that has been sealed over the years. Though the actual structural section on Koster Road is _ unknown at this time (and is beyond the scope of this study), the existing structural section should be based, as a minimum, on a 10-year TI value of 9.0 calculated based on existing daily traffic volumes assumed to remain constant for 10-years along this segment of Koster Road. — A review of the County's "Road Inventory"indicated that Blewett Road is also built on six-inches of base material that has been sealed over the years. Approximately 100-feet of Blewett Road at the approach to — Bird Road was reconstructed when Bird Road was improved. Though the actual structural section on Blewett Road is unknown at this time (and is beyond the scope of this study), the existing structural section should be based, as a minimum, on a 10-year TI value of 9.0 calculated based on existing daily — traffic volumes assumed to remain constant for 10-years on Blewett Road just east of Bird Road. Table 44 was prepared to present the calculated TI values on Bird Road, Blewett Road and Koster Road _ just south of the DeSilva Gates quarry entrance for existing (10-year TI value), year 2007 base (10-year TI value), year 2007 plus project (10-year TI value), year 2027 base (20-year TI value) and year 2027 plus project (20-year TI value) traffic conditions. The traffic operations analysis focused on peak month quarry production conditions and the daily traffic volumes shown on the traffic exhibits reflect peak — month daily volumes. The T.I. calculation is based on annual average daily traffic volumes or AADT. The calculated TI shown in Table 44 does not differentiate between loaded trucks traveling one way on the study area roadways with empty trucks traveling the opposite direction. 2"Draft DeSilva Gates Quarry Trafc&Circulation Analysis 46 October 2005 Jones&Stokes (R905TIS002/25-4000-02)