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Chapter 1 x Executive Summary <br />1-11 <br />1.4 Conceptual Design and Cost Estimates <br />Five to ten percent design was generally completed for the alternatives that were advanced <br />beyond the initial screening. Conceptual designs include bus options across either the Dumbarton <br />Highway Bridge or Dumbarton Rail Bridge and ROW; highway and approach options that include <br />express lanes along the Dumbarton Highway Bridge and Bayfront Expressway (SR 84), a tunnel <br />for Willow Road express lanes, bus-only lanes along Willow Road, grade separations at Bayfront <br />Expressway/Willow Road and Bayfront Expressway/University Avenue, and express lane <br />connectivity to US 101; and rail options to introduce Dumbarton rail service across the San <br />Francisco Bay using the Rail Bridge and ROW. Designs developed for connectivity to US 101 <br />assume that the existing HOV lanes on US 101 would be converted to express lanes in the future. <br />Conceptual designs were not developed for Alternatives 1 through 3, because capital <br />improvements are not proposed as part of the No Build Alternatives (Alternatives 1 and 3) and <br />Alternative 2 primarily contains transit and operational improvements. Conceptual designs for <br />Alternatives 4 through 10 were developed for the specific components that comprise each <br />alternative. Each alternative is subdivided into multiple variations — a base alternative and <br />permutations of that base. To the extent feasible, design elements may be eliminated or added to <br />the alternatives, and as a result several variations of one or more different options that could be <br />considered to improve mobility in the study area have been identified. Chapter 8 contains <br />additional details about the conceptual designs. <br />Operations and maintenance (O&M) costs and capital costs were developed for each alternative <br />except for Alternatives 1 and 3 because they do not include capital improvements. Annual O&M <br />costs for transit alternatives were based on the proposed service frequencies, operating hours, <br />and travel times specified in the operating plans described in Chapter 7. <br />The development of probable capital expenditure costs utilized two approaches: reliance on <br />previous cost estimates developed as part of the unpublished 2012 Dumbarton Rail Corridor <br />(DRC) Project Draft Environmental Impact Statement/Environmental Impact Report for rail <br />components of the alternatives; and development of new cost estimates for roadway and transit <br />components not studied previously or substantially modified by this study. The opinion of <br />probable capital costs is intended to allow comparisons between alternatives only and are not <br />indented for budgetary or funding purposes. <br />Table 1-2 summarizes the O&M and capital costs for Alternatives 2 and 4 through 10. Although <br />costs were developed for variations of several of the alternatives, costs for the base alternatives <br />only are presented below. Additional details about cost estimation methodology and results are <br />included in Chapter 9. <br />6.1.D. - Page 20