MONTPELIER — Aging infrastructure, a short construction season and the use of road de-icing salts all present challenges to Vermont’s efforts to keep up its bridges, but a report from the state Transportation Agency shows it’s making progress nonetheless.
An Associated Press review of federal data nationwide found that 7,795 bridges around the country were deemed both structurally deficient and “fracture critical.” Five of those troubled bridges were in Vermont.
The AP review analyzed data involving 607,380 bridges in the National Bridge Inventory that are subject to National Bridge Inspection Standards. On a national basis, there are 65,605 structurally deficient bridges and 20,808 fracture critical bridges, according to the most recently available federal government data.
A bridge is deemed “fracture critical” when it doesn’t have redundant protections and is at risk of collapse if a single, vital component fails. A bridge is “structurally deficient” when it is in need of rehabilitation or replacement because at least one major component of the span has advanced deterioration or other problems that lead inspectors to deem its condition “poor” or worse.
The four bridges that turned up in the federal data included one that crosses the White River on Vermont Route 107 in Bethel; one over the Otter Creek on River Street in Rutland; one over the Deerfield River on Vermont Route 100 in Readsboro; and one over the White River on a town highway in Hartford.
Mike Hedges, chief of the structures section at the state Agency of Transportation, gave an accounting on each of the four:
— The Bethel bridge was replaced this year and now is in new condition. It still is deemed fracture critical, which both Hedges and John Kedzierski, an engineer with the U.S. Army Corps, said is not as scary as it sounds. Hedges said this is true of all truss bridges, whose weight is borne in the structure above the deck. The truss design is still commonly used, and was in Bethel, in part to allow clearance under an adjacent railroad bridge.
— The Rutland bridge gets a “structure needs full replacement” description in a recent state inspection report, and that work is to be done by 2015, Hedges said. The project is in its final design phase now, and state officials are working to obtain the necessary rights of way to do the work, he added.
— The Readsboro bridge was approved by the Legislature for rehabilitation. Hedges said the project is in “scoping” now, meaning that preliminary planning is underway.
— The Hartford bridge is owned by the town, which got a $167,000 state grant and completed work on bearings, joints and concrete this past spring.
A fifth Vermont bridge given both designations is not open to general vehicular traffic. Crossing the Ompompanoosuc River in Thetford, it is located within the U.S. Army Corps of Engineers’ Union Village Dam recreation area. Corps officials said it is used by snowmobilers in the winter, as well as by Corps maintenance vehicles.
The Transportation Agency’s annual structures report said the state has been able to take advantage of increased federal funding in the past few years to step up bridge work. It contained a chart showing different types of the bridges and the percentage of each that had been deemed structurally deficient in 2007 and in 2012.
For interstate highway bridges, the percentage deemed structurally deficient dropped from 11.2 in 2007 and 4.2 in 2012. The figure for state highway bridges dropped from 20.5 to 10.0, while for town highway bridges it dropped from 19.0 to 11.2.MORE IN Vermont News
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