As part of the Ohio Department of Transportation’s aggressive bridge inspection and preservation program — with more than half-a-billion dollars having been directed to improving state and local bridges since the beginning of 2007 — the state’s highly-trained bridge inspectors use the latest technology, as well as lessons from the past, to keep Ohio bridges safe.
“Research is taking place all across the country on new ways to inspect and protect bridges. ODOT is applying new technology to extend the life of our bridges, and to make the ones we replace longer-lasting and more resistant to deterioration,” said ODOT Director James Beasley. “But even with ODOT’s aggressive investment into bridge preservation and modernization, we are looking at the legacy of the “Baby Boomer” bridges built during the Interstate era.”
Home to more than 42,000 bridges, Ohio requires more inspections on more bridges than any other state. Ohio is the only state to require annual bridge inspections — twice as often as federally required. All bridges in Ohio are looked at by inspectors who must go through a mandated ODOT bridge inspection training program.
Using sight, sound and touch, inspectors look at the bridge deck, superstructure, and the piers and abutments supporting the bridge. Aiding in that effort is an ultrasonic thickness gauge.
The device uses sound waves to measure the thicknesses of deteriorating steel members, much like an ultrasound performed by a doctor. Unlike older gauges that only measure thickness at single points, ODOT’s device rolls over the steel surface and provides thickness readings for the entire length of the bridge. This allows the inspector to pinpoint divots, dips and section loss.
Lessons learned from the past also are valuable tools. While no final conclusions have been reached in Minneapolis, federal investigators have suggested that a design issue with gusset plates on the I-35W bridge may have contributed to the tragedy. In 1996, two gusset plates on the I-90 East Bridge in Lake County had deteriorated and then buckled during a routine painting project. No one was hurt and the bridge was temporarily closed while the gusset plates were strengthened. Today, ODOT includes the unique training on gusset plates as part of its statewide bridge inspection training program.
In the year since the Minneapolis collapse, ODOT’s gusset plate training has received national attention.
Recently, Ohio’s U.S. Senator Sherrod Brown introduced legislation to provide tax credits to improve anti-corrosion technology that protects existing infrastructure. Corrosion can be a significant issue to the longevity of bridges, especially during Ohio’s rough winter season when the department uses salt on bridges to clear ice and snow.
“While the most cost-efficient solution to preventing corrosion on steel structures is painting, ODOT has investigated new technologies. The challenge has always been cost,” reminded Director Beasley. “Senator Brown’s proposal to offer tax credits for companies to improve and hopefully reduce the cost of new anti-corrosion technology will add to Ohio bridge preservation efforts.”
In marking the anniversary of the Minneapolis collapse, ODOT also has launched a new online public awareness effort to highlight bridge safety. In addition to receiving user-friendly definitions to engineering terms like “structurally deficient” and “functionally obsolete,” visitors to ODOT’s Bridging the Gap page will be able to learn more about the state’s bridge inspection program, including inspection information on bridges in their area.