The Bridgefarmer team, due to its vast experience with rail, DART, and its history of working on the SH 114 corridor, was instrumental in securing this contract.
The Northwest Corridor Irving DFW Line is divided into two line sections, I-1 and I-2, enabling DART to effectively manage the construction efforts of the build-out for this design-build project. Line Section I-1 will extend 5.4 miles generally northwest from its connection to the Farmers Branch/Carrollton Line to just southeast of the SH 114/Spur 348 interchange at the northern end of the Las Colinas Urban Center. Line Section I-2 will extend generally in a northwesterly direction from the north end of Line Section I-1 and terminate at a point near the intersection of Belt Line Road and Valley View Lane, on DFW Airport property. The length of Line Section I-2 is approximately 3.9 miles.
The project consists of three miles of light-rail guideway bridge structure with the track directly fixed to the bridge deck. The structures were analyzed for the rail force interaction and application of DART light-rail loading. Several straddle bent caps, each over 100’ in length, were post-tensioned to carry the applied loads. Over 15,000 lineal feet of various different types of retaining wall were designed to minimize the length of bridge structure.
The Northwest Corridor for DART’s new alignment crosses over the Trinity River. Bridgefarmer developed a special bolt-up girder design for the levee crossings. A major challenge on the project was the layout of the proposed bridge between the levee and the overhead Oncor power lines. To reduce the construction depth, the bolt-up section was used to meet the clearance requirements.
Work in the vicinity of the levee required complex hydraulics and modeling tools to be utilized to design for the discharge and the required mitigation. This work had to be done following levee requirements while paying close attention to structural details related to special light-rail electrical requirements.
Another significant achievement for Bridgefarmer was the design of precast panels for the DART light-rail bridges. Bridgefarmer championed the acceptance and implementation of the precast panels by DART. This innovative design was used as a DART standard throughout the Orange Line project and saved $100M in construction costs.