Bridge restrictions the result of weak support columns

Bridge restrictions the result of weak support columns

Matt Mead

The restrictions on travel across the Washington Avenue Bridge stemmed from concerns over how much weight support columns could withstand, engineering reports show. While largely structurally sound, officials partially closed the bridge over concerns when the columns connecting the vehicle and pedestrian decks were questioned. Concerns about the bridge arose after URS Corporation, an engineering firm, released a report designed to study how much weight the bridge could hold with the coming Central Corridor light rail line designed to run across it. The report was an âÄúeye-opening event,âÄù Hennepin County Engineer Jim Grube said, and it alerted county and University officials alike to the potential risk to pedestrians on the bridge. The report came just months after the bridge earned a 92.7 âÄî âÄúa fairly high ratingâÄù âÄî in an April Minnesota Department of Transportation inspection, meaning it would only need âÄúnormal maintenance,âÄù Grube said. But with the integrity of those columns in question, officials are now considering their options to fix the problem. âÄúWe donâÄôt have an answer yet,âÄù Grube said. Likely fixes could include bracing the columns to bolster them against the lower deck, he added, saying the bridge should reopen fully around April 1. With the weight capacity of those columns at issue, officials feared that too many pedestrians on one side or the other could add to the stress on the structure, Grube said. An Aug. 21 letter from URS officials to Hennepin County, which owns the bridge, urged a restriction of pedestrian access to a 14-foot-wide section running down the middle of the bridge. University officials announced the restrictions one day later. âÄúIt looks like there may be a situation where you could end up with an overloading factor,âÄù Grube said, âÄúwhere you have too many people on the bridge concentrated in certain spots on the bridge. âÄúThat resulted in us putting some fencing in, as you see today,âÄù he added. But with the light rail set to run across the bridge, it remains to be seen how it will react to the added weight, Grube said. âÄúThe mystery is starting to be solved,âÄù he said. While the columns are not critical supports of the bridge itself, every piece of the bridge is connected and equally important, civil engineering professor at the Rochester Institute of Technology Abi Aghayere said. âÄúIf any one of those members, if thereâÄôs a weakening or they fail, the structure as a whole fails,âÄù Aghayere, who specialized in bridge and building structures, said. Still, after reviewing the engineering and inspection reports, Aghayere said that in his opinion, the current fixes should suffice âÄî for now. âÄúItâÄôs OK to have this temporary fix, but they need to go there and really find out whatâÄôs going on,âÄù he said. âÄúIt behooves them, whoever is responsible for this bridge, to get onto it and fix it, so I hope theyâÄôre doing that.âÄù