Civil engineers have joined the chorus of Americans calling for better safety on U.S. bridges in the wake of Wednesdays deadly collapse of the I-35 steel truss span of the Mississippi River in Minneapolis, MN. The spans of the Twin Bridges are 75 and 42 years old. Both were built using the same construction method as the Minneapolis bridge. Are they at risk of catastrophic failure? University of Evansville Civil Engineers Mark Valenzuela and Chris Gwaltney dont think so. After taking a close look at the steel superstructure and piers, they say they couldnt spot any obvious trouble spots. But their visual inspection was brief. Bridges like the ones here can fail at steel joints due to cracking and splitting metal. Piers can be damaged by errant barges, and through crumbling concrete. But Chris Gwaltney says the biggest threat to bridges is a lack of funding. About 25% of the spans in the US are either obsolete or structurally deficient. Gwaltney says it would take nearly double the annual road budget just to fix the ailing bridge situation. He says the failure of the Minneapolis bridge will call attention to the plight, but worries that, like previous failures, the attention will fade. "Its always a wakeup call, but they dont stay awake very long," he said, referring to politicians who fund road work.