By: Matt Scher, matts@977thebolt.com
Humboldt County, IA – The future of the historic Murray Bridge in Humboldt County appears uncertain after a recent engineering inspection found extensive structural damage caused by a collision involving farm equipment.
According to a report from Shuck Britson, Inc. provided to Humboldt County Engineer Ben Loots, an unidentified piece of farm equipment struck multiple steel truss members and approach rails while crossing the bridge in May. Inspectors documented damage to numerous fracture-critical members on both sides of the bridge, including several members with torn steel, significant bowing and rotation.
The bridge had already been posted with a 3-ton weight limit before the collision and has remained closed since the incident. In its report, Shuck-Britson Incorporated recommends the bridge remain closed to all traffic, stating the structure is now in a much worse condition than before the collision.
The inspection report downgraded the bridge’s superstructure condition rating to a 1, or “Imminent Failure Condition,” under National Bridge Inspection Standards because of obvious structural movement affecting the bridge’s stability.
Engineers also concluded that repairing the bridge is likely not practical. According to the report, restoring the bridge to its pre-collision condition would require temporary shoring or moving the bridge to land, straightening and strengthening damaged truss members, replacing damaged approach beams and rails, and using a specialty bridge contractor because of the bridge’s age and historic nature.
Shuck Britson, Inc. noted that Humboldt County is already planning to reroute the Farm-to-Market Road and construct a replacement bridge north of the existing crossing. By the time repairs could be designed, bid and completed, construction of the new bridge would likely already be underway. As a result, the engineering firm concluded repairing the existing bridge would not be a practical use of county resources.
Inspectors found no collision-related damage to the bridge foundations, and the deck itself did not appear to have been affected by the impact.
Murray Bridge has remained barricaded since the collision while county officials review the engineering report and continue planning for the bridge replacement project.