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Title
Design Services for Rock Island Road Bridge Replacement at Bear Creek
Presenter
Romin Khavari, City Engineer
Recommended Action
Approve
Analysis
In 2012, Dallas County engaged Kimley-Horn (KH) to provide a Bridge Scour and Bridge Condition Assessment Study. The study noted that erosion presented a significant risk to the bridge’s substructure. Since funding was not immediately available at the time to implement the Study’s preferred technical alternative of replacing the bridge, an interim erosion mitigation measure was proposed. In 2013 Dallas County engaged KH to design the interim erosion mitigation measure to protect the bridge’s header banks and abutments against further erosion and to structurally reinforce the bridge bents. Under this proposed scope and fee, the City of Grand Prairie and Dallas County have requested KH to perform the tasks necessary to develop the preliminary design to replace the existing bridge with a new bridge.
The ultimate typical street section for Rock Island Road will be four-lane divided. The proposed crossing at Bear Creek will be two, twin bridges matching the 4-lane divided typical section and will be approximately 320-feet long. A hydrologic and hydraulic study will be performed on Bear Creek as a part of this scope to determine the length and elevation of the bridge structures. Under this scope of services, only the preliminary design for both (twin) bridges will be provided. The City and County will phase the implementation of the ultimate road and bridge improvements by just building one of the two proposed bridges. The length of embankment and roadway improvements beyond the ends of the new bridge will be limited to the shortest distance that will allow the roadway to tie back into the existing two-lane roadway. Preliminary design for the demolition of the existing bridge, approaches, and header banks will also be provided to improve existing channel geometry and to reduce stream velocities and other erosive concerns upstream. Preliminary design of city utility crossings and coordination with franchise utilities are also included as a part of this scope.
The new bridge and future bridge will require new embankments within the existing floodplain to serve as the proposed bridges’ header banks and roadway approaches to the bridge. Coordination with the U.S. Army Corps of Engineers (USACE), the Federal Emergency Management Agency (FEMA), the City of Grand Prairie, the City of Irving, and the Dallas County Flood Control District No. 1 will be required. It is anticipated that the project will fall under a Nationwide Permit 14 (NWP-14) for linear transportation projects and an individual permit is not anticipated.
This is a joint project with the City of Grand Prairie and Dallas County. Historically, these joint projects have had the engineering contract with Dallas County for both preliminary and final design and Dallas County has served as the lead agency managing the consultant and the project. In this case, the preliminary design contract will be with the City of Grand Prairie and the future final design contract will likely be with Dallas County. We understand Dallas County will remain the lead managerial agency for this project throughout preliminary and final design, as well as construction.
Financial Consideration
No funded required at the current time.