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i� J �OJGpT10N oq A` ' I arldge Structural Design Services A. Project Understanding and Approach DMJM Harris is excited to be given the opportunity to participate on this bridge rehabilitation project with the City of Santa Ana. As leaders in the transportation engineering world, we understand the complexities associated with the highway bridge rehabilitation and replacement (HBRR) program and the intricate coordination necessary between the City and the various stakeholders and permitting agencies. We recently completed a City of LosAngeles bridge improvement project involving HBRR funding for five bridge structures. This project required extensive coordination between various agencies such as Caltrans, the U.S. Army Corps of Engineers, the L.A. County Flood Control District, and the Regional Water Quality Control Board. DMJM Harris staff has conducted a preliminary field review of the First Street Bridge across the Santa Ana River to assess the feasibility and impacts of the bridge rehabilitation project at this location. Based upon this field review, and the requirements dictated in the RFP, and review of record drawings, we have identified key project issues that we will discuss further in our Project Understanding, Project Understanding The First Street Bridge across the Santa Ana River channel (Photo 1) is a continuous 9 -span Cast -In -Place (CIP) Reinforced Concrete (RC) T -girder bridge including 2 cantilever end spans, all supported on RC pier walls on timber piles and concrete piles. The bridge was originally constructed in 1937 and widened in 1959. A seismic retrofit of the bridge was completed in 2005. The bridge currently canes a pedestrian sidewalk and two lanes of traffic in either direction. The HBRR program provides federal -aid to local agencies to replace and rehabilitate deficient locally owned public highway bridges. Bridges must be rated Structurally Deficient (SD) or Functionally Obsolete (FO) with the Sufficiency Rating (SR) < 80 to be eligible candidates for rehabilitation. The First Street bridge is rated SD with a SR of 71.2 thereby placing it in the Eligible Bridge List. DMJM HARRIS I AECOM Bridge Design Elements There are many site and operational constraints that affect the selection of the optimal structure types and configurations for the First Street Bridge Rehabilitation project. The purpose of this section is to give a brief description of key factors which must be considered in the bridge type selection process. Construction Schedule The most significant construction constraint is the need to maintain traffic on First Street during the construction period. Another key factor is the requirement that no work be performed within the river bottom during the rainy season. DMJM Harris has completed design of a number of bridge structures across the various rivers with constraining construction schedule within the river. The Union Pacific railroad bridge across the Los Angeles river (Photo 2) required a staged construction sequence to replace an existing single track railroad bridge with a three track bridge. The staging accounted for maintaining traffic during construction as well as for a six month work window in the river. Photo 2. DMJM Hams designed the UPRR bridge across the Los Angeles River. Photol. Existing Santa Ana River bridge. 04601 324.5557