This project encompasses the repair of the U1 truss joint on a 450' double track swing span over the Columbia River in Vancouver, Washington. The bridge carries 24MGT and 10 passenger trains per day; and averages 300 openings per month. Minimizing track outages, maintaining the clearance envelope, and maintaining the stability of the truss joint during the repair were the major concerns addressed during the design phase of this project. Keeping the design in-house and utilizing local vendors maximized efficiency in design and construction of this project. Routine inspection revealed the cracked end portal cover plates. Subsequent in-depth inspections revealed that the pin plates at the U1 truss joints were elongated, allowing excessive joint movement. Options considered to tighten the joint include pin replacement, exterior member strengthening, and post-tensioning. The post-tensioned repair was chosen as an easily inspected and maintainable near term solution to extend service life, minimize traffic impact, and reduce construction cost. Post-tensioning was achieved with a split pin saddle, high strength threaded rods, and bolted anchorage blocks that allow the rods to hold each pin plate tight against the pin. It is expected that these rods will have a service life of 5-10 years. While this bridge is not expected to be replaced in that time, the maintenance cost of replacing these rods was deemed acceptable. Completed in the fall of 2014 with minimal track and river outages, the project achieved the design goals of closing the cracks and reinforcing all four joints. Most importantly, this was accomplished with zero injuries.
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