Wood rot in timber bridges leads to detours in Hamilton County
NOBLESVILLE, Ind. (WISH) — New and unexpected detours in Hamilton County may point toward a much larger problem.
The county has shut down two of its many timber bridges because of concerns about the wooden beams that support them.
Timber bridges are common around the state and across the country, particularly along county roads in spots where they cross creeks, streams, ditches, and other low areas. Many have load limits, to prevent large trucks from overstressing them.
Drivers may not notice many timber bridges, because they typically cover much shorter spans and are lower-profile than the steel structures used on higher-traffic roads and highways.
The Hamilton County Highway Department says there are 66 timber bridges in the county. At least half of them are at least 30 years old, and many are deteriorating faster than expected.
“We have been discovering an increased frequency of core rot of substructure caps,” Bridge Program Engineer Matt Lee said in a statement provided by the county. “That’s when the timber develops cracks, allowing water to penetrate the wood and rot it from the inside out.”
A highway department spokesperson says the county does not know how many bridges may be rotting and it will address them as inspections reveal problems.
One of the bridges now closed is on Atlantic Avenue, over Stony Creek, along the county line just west of Lapel.
The highway department says the bridge has a fracture at the center of it, likely because someone drove a heavy load over it.
Lee says the county needs to replace the whole bridge, so it will be closed for a very long time.
“We have selected a design firm and asked them to expedite the project,” Lee explained. “But we’re looking at a closure of at least two years.”
The other bridge currently off-limits is on 246th Street where it crosses Bear Creek between State Road 213 and Brehm Road. Inspectors found problems with it during inspections done every two years.
In this case, engineers say it can be repaired, and they expect it to open in late December.
Hamilton County Highway Director Brad Davis said about the detours, “While the closure of these bridges may cause temporary inconvenience, the safety of the public remains our utmost concern.”
As for the dozens of other wood-supported bridges across the county, leaders indicate they’re working to deal with problems as they find them and head off future concerns before they happen.
Lee says, “We are working with our timber supplier and local engineering firms to develop effective detection and repair strategies to help reduce timber rot that could create similar future bridge closures.”