IH 635/Dallas North Tollway Split Diamond Traffic Signal Design

The intersections at the Dallas North Tollway and IH 635 in North Dallas had older, substandard traffic signals connected to a bridge that required replacement. The Texas Department of Transportation (TxDOT) needed to find a solution to replace the signals, which are all elevated and could not be attached to the bridge structure.

TxDOT reached out to BGE to assist with this challenging project. Upon BGE’s analysis, the traffic design team determined that two mast arms could be replaced with one dual mast arm at each of the intersections. BGE’s traffic and structural teams were able to design large columns to not only support the traffic signals poles, but two of the poles now also have pole-mounted traffic signal cabinets with a catwalk structure and handrails to allow signal technicians safe access to the signal cabinets. There was an issue with voltage drops during the project due to the distance from the power drop to the signal cabinets, but step-down transformers were designed to account for this.

In addition to assisting TxDOT on this project, the City of Dallas could finally replace the one centrally located signal cabinet that was cantilevered over the IH 635 main lanes. Further coordination and approval were conducted with the city, which will now operate and maintain the traffic signal. BGE also coordinated with NTTA since their right-of-way is where the traffic signal columns are located. The new signal was activated in April 2021.