On Aug. 1, Minnesota will mark the five-year anniversary of the fall of the Interstate 35W bridge. As a state, we will remember the 13 fellow citizens who died and the 145 friends and neighbors who were injured -- many permanently.
My friend and neighbor Pat Holmes died on the bridge. Since that day, I have been waiting for URS, the company that was hired by the state to evaluate the integrity of the bridge, to apologize and to accept responsibility. Instead, URS had its insurance company pay a record-setting $54 million settlement to avoid exposure to a punitive-damages award and a day of reckoning with a Minnesota jury.
And it has been quite successful in lining up more state and local contracts. (While the Metropolitan Council has decided not to give URS the entire $94 million contract to engineer the new Southwest Corridor light-rail line from Minneapolis to Eden Prairie, the company could still bid and be awarded a substantial contract.)
In the midst of all this comes the news that cables on the URS-designed Sabo Bridge were brought down by light winds of as little as 6 miles per hour because of a "vortex shedding" phenomenon well-known to bridge engineers and to anyone familiar with the 1940 Tacoma Narrows Bridge collapse, an event viewable on YouTube. In a nutshell, the light force of the wind causes the bridge cables to vibrate; the magnified forces of the vibrations were enough to cause the cables to snap.
"The phenomenon can typically be controlled with even a small amount of damping," concluded the independent WJE Engineers Report. In other words, there was a cheap and easy solution that was simply missed by URS.
Now, a good company -- a responsible company, and the kind of good corporate citizens we like to do business with -- would acknowledge this gross mistake, apologize and make amends. But URS's response tells us a lot about what kind of company it is.
It seeks to cast blame on others. It seems to seize on the fact that the independent WJE Report criticizes some welds and the positioning of some plates. Yet, the report concludes that the vortex shedding problem, and URS's failure to correct for it, was the driving force that brought these cables down. The welds and plate positioning simply aggravated the problem.
Next, in a letter quoted at footnote 1 of WJE's report, URS pointed out that it considered wind-induced vibrations during design, but that it deferred a final decision on damping until after construction. Then, after monitoring, "URS concluded that the observed vibrations were acceptable and stay cable dampers were not necessary."
