Until March 16, everything was coming together very nicely on the new bridge at 102nd Avenue over Groat Road in Edmonton, Alberta. Two days earlier, the crew from fabricator and erector Supreme Steel had placed and bolted the first of seven central girder sections that would complete the span. Winds interrupted work for awhile, but by Sunday night crews resumed girder placement until six sections were up. Then, at about 2:15 a.m. on Monday, March 16, four of the girders buckled laterally, three deflecting several feet and leaving interior braces bent or dangling, according to city officials. Work stopped and crisis management began.
"We don't see many of these types of failure," said Carlos Cruz Noguez, assistant professor of structural engineering at the University of Alberta.
The girder deflection, which Cruz Noguez and other engineers attribute to torsional lateral buckling, is shown in many photos, taken by an internet- enabled jobsite project camera. "It's visually amazing," said Cruz Noguez.
Edmonton's road design and construction manager, Barry Belcourt, seemed to be experiencing more stress than amazement in the days that followed, with the traffic delays caused by the closing of Groat Road, which runs beneath the span.
The Edmonton Journal reported that Belcourt told the media on Tuesday, March 17, that the delay was his responsibility, saying, "And we should have the pressure on us. ... It's my responsibility to deliver this project. You think we sleep at night? No. The team I'm working with and the contractors, we're embarrassed by this."
The project's contracting team, which includes the Los Angeles-based contractor AECOM and Calgary-based Graham Construction, declined to comment, citing restrictions placed on them by the city. Edmonton-based Supreme Steel also declined to comment.
Thanks to quick work by the construction team, which moved in shoring and cranes to hook sections of the structure, and the elastic nature of steel, the girders straightened. By April 7, traffic under the span flowed again.
Whether the contracting team will end up footing the bill for the as-yet- unspecified delays is a multimillion-dollar question. City officials declined to reveal details of contractual penalties for late completion, which originally was set for October. The construction team already has been penalized $15,000 for each day that Groat Road was closed; the total fine exceeded $300,000.
The new bridge had an initial budget of $32 million. The span stretches roughly 100 meters over Groat Road; the banks on each end were stablized with soil nails. The bolted, three-section girders are roughly 4.2 meters deep at their ends, which are encased in concrete abutments.
Construction crews actually started installing the girders on Friday night, March 13, but had to stop work on Saturday night due to high winds, according to city engineering officials.
They are overseeing a review of the project by Vancouver-based bridge engineer Buckland & Taylor. City officials say the range of causes being probed includes the high winds that forced girder erection to stop on Saturday night, girder bracing and erection procedures.