25G - ENGINEERING SRVS GRADE SEPARATION

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Public Utilities Commission Commission's Order Authorizing Construction of the Grade Separation This work is not part of the Phase 1 Scope of Services, rather it shall be done during Phase 2. Commission's Order Authorizing Alteration of the Existing At-grade Crossing This work is not part of the Phase I Scope of Services, rather it shall be done during Phase 2. Task 1.6 Structural Analyses/APS Structures Development of the PSRE and PSR will require the preparation of a bridge Advance Planning Study (APS) for Santa Ana Boulevard Underpass. The purpose of the APS is to evaluate feasible structure types, understand City requirements, identify constraints, and develop associated cost estimate summary for the structure work involved. The APS General Plan (GP) clearly delineates all the structural elements identified in the PSRE and the PRE typically using the minimum detailing necessary and basic dimensions, which will help develop a reasonable cost estimate. As a minimum, the APS GP will show Plan, Elevation, and Typical Section views and will make note of all critical assumptions. Additional APS's will be prepared as appropriate to consider alternative structure types. The APS General Plan and APS Report will be prepared on the most current Caltrans APS formatted plan sheet, and templates respectively. Structure Preliminary Geotechnical Reports (SPGR) are required as part of APS to identify basic site parameters, which may have a significant impact on the structure scope and cost. In addition, a comprehensive design memo must be prepared to summarize and document the following key items: # important or unusual design assumptions or structure features. .6 Discussions with City/OCTA/SCRRA personnel concerning any key assumptions. .l. Modifications from Structure Maintenance Records recommendations. .L1 Seismic retrofit modifications. 6 City requirements such as aesthetics, improvements in vicinity of the structure, airspace usage, or other obstructions. .4 Special foundation requirements, special excavations such as Type A, Type D, and/or hazardous or contaminated material. .L Special construction requirements, including limited site accessibility. .L Stage Construction. The information identified in the APS, as listed above, and preliminary structure costs are used as a part of the evaluation to select the best project alternative. Santa Ana Boulevard Underpass It is proposed to construct a railroad bridge by lowering the Santa Ana Boulevard- A 2-Span Structure Alternative would work very well at this location. This proposed double track railroad bridge structure is approximately 126.7 feet long and 40.3 feet wide, with no skew to Santa Ana Boulevard. A Pier Bent is needed in the median of Santa Ana Boulevard, which will result in the maximum span length of 63.3 feet, and therefore a SCRRA Standard Precast/Prestressed (PC/PS) Double Cell Box Girder Structure can be used for the structure type. Precast units can expedite the construction schedule, helping to reduce impacts to both the rail and the road traffic. In addition, a precast, simply supported structure is the preferred railroad bridge type because of its flexibility for repair and replacement in the future. Significant shoring would be required around the construction area when constructing the bridge. Retaining walls would be required for both the roadway depression and the raise of the Crrv o/ Sawa A- 25G-158