The collapse of a bridge is a horrifying event, one where the reality can be just as bad as whatever a movie studio can dream up. Cities and counties do what they can to keep bridges in good shape so that the people on the bridge can cross safely. Unfortunately, bridges do age, and all that sturdy concrete and metal can weaken enough to fail. If you're thinking inspections will be enough to monitor the bridge in your town, think again; while inspections are definitely important, they don't always predict when a bridge should be shut down for safety reasons.
The I-35 Bridge Collapse, and All Its Prior Inspections
In 2007, a bridge carrying I-35W traffic in Minneapolis collapsed into the Mississippi River, taking several cars and trucks with it. The bridge had long been under observation because of deteriorating conditions, with plans to retrofit the bridge on hold because the work could have actually made the bridge's condition worse. There was speculation that the bridge could have been heading for a collapse based on frequent visual inspections, but no one took steps to close down the bridge, which was on a major route. The steel supports eventually failed.
The Point of Having Many Sensors
The bridge was rebuilt quickly, this time with many, many sensors to monitor the condition of the bridge as its loads and environments change. Not only will the sensors give researchers information for future bridge building, but the sensors should be able to give the city warning if part of the bridge experiences too much stress to the point where the bridge needs to be shut down. A few sensors can't collect the total data needed to definitively monitor a big, heavily used bridge. Adding many sensors gives a more complete picture.
The Danger Can't Be Overstated
Too many bridges in the United States are considered structurally troubling. Rather than take a chance that the bridges in your area will be fine, get sensors on them and start monitoring them. You can't ignore the risks because the consequences are so bad if you're wrong and the bridge can't handle one more day of traffic.
Put the bridges in your area through thorough inspections to get a baseline, and then have sensors installed on each one. Shut down any bridges whose bridge monitoring sensors show indications that the bridge is experiencing too much stress. The safety of your residents and tourists is worth it.