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yNJC PY..ION '9A Bridge Structural Design services Seismic Resistance The bridge widening will need to be designed in accordance with current Caltrans Seismic Design Criteria. The seismic adequacy of the existing bridge structure in conjunction with the proposed widening measures needs to be addressed. DMJM Harris is well versed in the latest developments in seismic design and has completed a number of projects for local agencies and Caltrans in accordance with the current seismic standards. Foundation Conditions The constraints imposed by location of piles supporting the portion of the bridge to be demolished, traffic, and construction schedule will influence the foundation type for the bridge. Moreover, the SCE & AT&T overhead lines to the north imposes clearance limitations. Two types of foundations are feasible, driven piles supporting pier walls similar to the existing bridge or cast -in -drilled hole (CIDH) piles constructed within a temporary or permanent steel casing. In areas where there are overhead lines, CIDH piles or spliced driven piles may need to be considered (Photo 3). Flow walls between the CIDH piles and cast -in-place nosing need to be provided for hydraulic considerations. DMJM HARRIS I AECOM Cost 6 ; With increasing competition and constraints for funding on transportation projects, construction cost is an overriding concern. A cost-effective structural solution is mandatory in today's environment, however, true costs must be accurately determined to arrive at a proper solution. To obtain a true project cost, adequate attention needs to be given to all factors contributing to cost not solely cost of furnishing and erecting materials. DMJM Harris' wealth of experience in designing highway bridge widening projects in Southern California provides us with an especially valuable database of cost information. Our Team will choose the appropriate data to utilize for this project to develop accurate cost estimates on which we can base our design decisions. Superstructure Type: Construction staging dictates demolition of a 21 -foot portion of the north structure during Stage 1 and the remaining 20 feet in the final stage. To ensure compatibility with the preserved section of the south structure, a CIP RC T -girder bridge superstructure will be the most prudent choice. RC T -girder bridges are cost competitive for the span ranges under consideration. Construction would be performed in two stages as described in the forthcoming section. Photo 3. Overhead utility lines will impact foundation construction methods. added. 04601 324.5557 Photo 5. Existing bridge deck.