AECOM 1 - 2011 - Laserfiche WebLink

Home Browse Search

■ AECOM Task 1.6 Structural Analyses/APS Development of the PSRE and PRE 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 wilt 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. • Discussions with City/OCTA/SCRRA personnel concerning any key assumptions. • Modifications from Structure Maintenance Records recommendations. • Seismic retrofit modifications. • City requirements such as aesthetics, improvements in vicinity of the structure, airspace usage, or other obstructions. • Special foundation requirements, special excavations such as Type A, Type D, and/or hazardous or contaminated material. • Special construction requirements, including limited site accessibility. • 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 Bo�utevard 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 rail profile. In order to facilitate the traffic staging/handling during the construction, the walls constructed parallel to Santa Ana Boulevard could be constructed using "top-down" construction; that is to build the wall first, and then excavate the roadway in front of the wall to final grade. We will perform Value Analysis to determine the most cost effective retaining wall type, top down approach vs. conventional cantilever retaining wall using temporary shoring. A Single Span Structure Alternative can also be considered. The span length required to span the Santa Ana Boulevard roadbed is approximately 134'. The typical span range for this type of construction extends to about 150 -ft under Cooper E-80 loading. Therefore, even though the required span is nearing the upper limit of the typical structure span length, this structure type is suitable for construction of new underpass. The total structure depth for the replacement of the double track would be approximately 13'-6". Provisions can be made in the bridge design so that is capable of supporting a future third track, should this become a requirement of OCTA/SCRRA. To support a possible third track, the through girder, on the either left or right side of the underpass, will be required to have a structure depth approaching 15' in orderto support the full weight of a Cooper E-80 live load. During the APS development, through a careful and deliberate process, we will study a number of different structure alternatives and configurations against various interchange alternatives, and develop associated costs. Deliverables.- 0 eliverables:• Draftand Final Structure Type Selection Report Task 1.7 Existing and Future Utilities Issues/Permitting We will identity and coordinate with the various utility companies for the location and descriptions of their facilities, including any potential for future utility improvements. Utility Meetings and Utility Coordination Coordinate and schedule meetings with Utility Owners and project stake holders as may be required. Proposal for Project Study Report Equivalent and Conceptual Engineering Plans for Santa Ana Boulevard Grade Separation Project