25G - ENGINEERING SRVS GRADE SEPARATION

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AECIIV . . ~~~~i~~.°~~w~~~~:~.L. ~ Structure can be used forthe structure type. Development of the PSRE and PRE will require the preparation of a bridge Advance Planning Study (APS) Precast units can expedite the construction schedule, for Santa Ana Boulevard Underpass. The purpose of the helping to reduce impacts to both the rail and the road APS is to evaluate feasible structure types, understand traffic. In addition, a precast, simply supported City requirements, identify constraints, and develop structure is the preferred railroad bridge type because associated cost estimate summary for the structure of its flexibility for repair and replacement in the future. work involved. The APS General Plan (GP) clearly Significant shoring would be required around the delineates all the structural elements identified in the construction area when constructing the bridge. PSRE and the PRE typically usingthe minimum detailing Retaining walls would be required for both the roadway necessary and basic dimensions, which will help depression and the raise of the rail profile. In order to develop a reasonable cost estimate. As a minimum, the facilitate the traffic staging/handling during the APS GP will show Plan, Elevation, and Typical Section construction, the walls constructed parallel to Santa views and will make note of all critical assumptions. Ana Boulevard could be constructed using "top-down" Additional APS's will be prepared as appropriate to construction; that is to build the wall first, and then consider alternative structure types. The APS General excavate the roadway in front of the wall to final grade. Plan and APS Report will be prepared on the most We will perform Value Analysis to determine the most current Caltrans APS formatted plan sheet, and cost effective retaining wall type, top down approach vs. templates respectively. conventional cantilever retainingwall usingtemporary shoring. Structure Preliminary Geotechnical Reports (SPGR) are required as part of APS to identify basic site A Single Span Structure Alternative can also be parameters, which may have a significant impact on the considered. The span length required to span the Santa structure scope and cost. In addition, a comprehensive Ana Boulevard roadbed is approximately 134'. The design memo must be prepared to summarize and typical span range for this type of construction extends document the following key items: to about 150-ft under Cooper E-80 loading. Therefore, even though the required span is nearingthe upper limit • Important or unusual design assumptions or of the typical structure span length, this structure type structure features. is suitable for construction of new underpass. The total • Discussions with City/OCTA/SCRRA personnel structure depth for the replacement of the double track concerning any key assumptions. would be approximately 13'-6". Provisions can be made • Modifications from Structure Maintenance in the bridge design so that is capable of supporting a Records recommendations. future third track, should this become a requirement of • Seismic retrofit modifications. OCTA/SCRRA. To support a possible third track, the • City requirements such as aesthetics, through girder, on the either left or right side of the improvements in vicinity of the structure, underpass, will be required to have a structure depth airspace usage, or other obstructions. approaching 15' in order to support the full weight of a • Special foundation requirements, special Cooper E-80 live load. excavations such asTypeA, Type D, and/or hazardous or contaminated material. During the APS development, through a careful and Special construction requirements, including deliberate process, we will study a number of different limited site accessibility. structure alternatives and configurations against Stage Construction. various interchange alternatives, and develop associated costs. The information identified in the APS, as listed above, and preliminary structure costs are used as a part of the Deliverables: evaluation to select the best project alternative. Draft and Final Structure Type Selection Report I i i ~~d If~ ~ ~ ~ l .R iii llii i It is proposed to construct a railroad bridge by lowering the Santa Ana Boulevard. III ~~lo ~ilil~~t~~~~~ We will identity and coordinate with the various utility A 2-Span Structure Alternative would work very well at companies for the location and descriptions of their this location. This proposed double track railroad facilities, including any potential for future utility bridge structure is approximately 126.7 feet long and improvements. 40.3 feet wide, with no skew to Santa Ana Boulevard. A Pier Bent is needed in the median of Santa Ana Utility Meetings and Utility Coordination Boulevard, which will result in the maximum span Coordinate and schedule meetings with Utility Owners length of 63.3 feet, and therefore a SCRRA Standard and project stake holders as may be required. Precast/Prestressed (PC/PS) Double Cell Box Girder r~i f~, fr. ~~,.y~on. 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