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Instead of beginning with the south truss, as the contract amendment specified, MnDOT inspectors began on the north end of the bridge and worked south. The agency did not inspect all of the targeted trusses on the south end.
Asked about the change, Kender wrote, "When the amendment was written we assumed inspections would be done from below with manlifts to minimize disruption to traffic." Instead, inspectors used a "snooper" vehicle, "to provide better access for the inspectors. Logistically, it made more sense to inspect one complete side of the bridge at a time, starting at the traffic approach end and traveling in the direction of traffic to the traffic departure end, north to south in the west lane, and then moving to the other side."The order of inspections was set by ease of access; there was no engineering reason to inspect one end or side before the other."
Asked why the agency couldn't inspect the entire bridge in May, Kender said the agency had intended to inspect only some of the critical bridge elements in May, then review the inspection procedure in late August before completing the task in the fall. She said URS would have participated in the August review of the May inspections.
The special inspections in May concentrated on critical elements of the bridge identified by URS. MnDOT had scheduled its regular annual inspection, held in recent years in June, for September.
The handwritten notes from the May inspection -- accompanied by close-up photos of the bridge -- give no indication that MnDOT found serious problems at the time, and are couched in technical language. The partial inspection, according to explanatory notes provided by MnDOT, "only looked at certain truss members (called chords), those identified in the URS study as critical."
Corrosion but no cracks
An accompanying drawing of the bridge, with its many trusses numbered in sequence, shows that workers initially concentrated on the bridge's west side, starting from the north end.
The notes offer glimpses of what was found. For example, notes referring to truss L2' West, plate 2-2', on the bridge's north end, state that workers found "full length welds, bottom flange corroded 1/2 length of bottom weld -- up to 3/32" loss."
The notes indicate that inspectors did ultrasonic testing for undercut and porous areas in the welds and found some. "No crack noted."