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documents or information from an affected area to develop significance criteria. For the purposes of this transportation impact analysis, the evaluation criteria described in Table 4.3.3 defines significance. The transportation impact analysis identifies impacts to roadways, intersections, public transit service and ® pedestrians and bicyclists for project start up and for a cumulative operation year of 2010. To do so requires the analysis of four scenarios, which include: • Existing conditions; • Existing plus project conditions; • 2010 no project conditions; and • 2010 project conditions. In general, this transportation impact analysis determines the effect project generated traffic would have on the operation and safety of the local transportation system and its users. The remainder of this section documents the analysis results and impacts and mitigation. Analysis Results The basis for this transportation impact analysis is the type and amount of project generated travel demand estimated to use or affect the following transportation system components: • Roadway structural conditions; • Intersection operations and safety; • Public transit service; and • Bicycle and pedestrian routes. ® The traffic calculations contain estimates of the amount and type of traffic generated by the proposed project, and are on file at the Community Development Department, while Appendix C contains a discussion of the methodology used to generate, distribute and assign project traffic to the transportation system. The following discussion provides the information necessary to determine impact significance. Roadway Structural Conditions The structural section of a roadway can be defined as the combination of materials placed in layers above the top of the basement soil (California Department of Transportation, Highway Design Manual, July 1, 1990). Although design of the structural section depends on many variables, a calculation known as the Traffic Index (TI) determines the relationship between the structural section material composition given the ability of the base soil to carry the load of the structural section and traffic using the roadway. The basis for the TI calculation is the annual average daily traffic (AADT) estimate for the roadway design year (typically 20 years after the construction year) categorized for 2, 3, 4 and 5 or more axle vehicles. Table 4.3.4 compares the TI calculations for a 2010 design year under the no project and proposed project scenarios (TI calculations are on file at the Community Development Department). 1 ER -93-1 -51 - (9-27-93)