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Span costs millions to maintain but danger still lurks

first_imgAt 100 years old, the northbound span of the Interstate 5 Bridge has allowed millions of people from several generations to easily travel between Vancouver and Portland, but not without a lot of work and public investment.“It doesn’t come cheap to maintain an older bridge of that particular design type,” said Bruce Johnson, state bridge engineer for the Oregon Department of Transportation.ODOT operates and maintains the bridge, but the costs are split between its owners, Oregon and Washington.To many living in the region, the Interstate Bridge is just one feature of a regular commute. But Johnson sees an old structure with lots of maintenance needs.Steel truss bridges, such as the I-5 Bridge, are flexible by nature; that combined with the fact that the bridge is old, supports loads far greater than it was designed for, has issues with corrosion and was riveted together — which makes it prone to fatigue cracks — can cause a feedback loop of problems.Johnson says ODOT has ways of monitoring and repairing damage as it arises. But as Oregon’s infrastructure inventory grows and more bridges age beyond their design lifespans, he worries about being able to stay on top of all the problems.last_img read more