Niles Truss Bridge Evaluation

When it was constructed in 1899, the pin-connected truss spans of the Niles Railroad Bridge over the St. Joseph River carried two tracks. Today, the bridge has only one active track. Traditional methods of inspection call for rail-mounted equipment. But Amtrak could ill afford to tie up the only remaining track on the bridge for the procedure. The solution to their dilemma seemed obvious: Amtrak needed a firm capable of inspecting all 112 bridge pins while minimizing rail service disruptions.

Mindful of Amtrak’s service disruption concerns, we quickly ruled out the use of rail-mounted inspection equipment. Instead, our innovative inspectors implemented technical and rope access methods to aid in the instrumentation and testing of all bridge pins. Working in teams of two, Modjeski and Masters' experienced inspection crew climbed to each truss joint and used ultrasonic testing (UT) to find defects in the pins. We tested all 112 bridge pins with zero service disruption to the active track. Additionally, we provided illustrated findings and an ultrasonic pin testing report that laid the groundwork to develop necessary connection retrofit designs. A creative approach plus an innovative solution.