By: Donovan W. Mann – [email protected]
Dakota City, IA – The Humboldt County Secondary Roads Department is doing some repairs on a bridge resulting in a closure.
On Monday, April 19, during the meeting of the county’s board of supervisors, Engineer Ben Loots informed them of a project they recently began. This is a deck replacement for Bridge 39 which will be shut down until they repair it.
The bridge in question is located on Quebec Avenue, a gravel road. The secondary roads crew, which is coming from the Hardy shop, hauled eight loads of rock from the bridge to inspect the wood planks that make up the deck. Loots says that after doing so they found “a lot” of rotting wood.
The engineer speculates that due to the amount of rock on the bed along with the “tongue and groove” method of laying the wood, water got trapped on the deck resulting in the rotting. The rest of the structure is still in good condition so they will just be replacing the deck.
The plan is to salvage as much of the wood from the original deck as possible. Loots says they hope to salvage about 20 percent for the replacement deck. The other 80 percent will come from their stock in Dakota City. This stock pile was created after a different bridge replacement project.
Instead of going back to the tongue and groove method where there is no spacing between the wood for water to flow they will leave about half-an-inch-gap between planks. This should allow water to pass through but still hold the rock that goes over the wood.
Bridge 39 was built in 1971 and caries roughly 45 vehicles a day. In November of 2020, when it was last inspected by Shuck-Britson, Inc., it received a rating of 92.3. However, this was without the removal of the rock that covered the bed to inspect the bridge.
The board did ask their engineer about replacing the bridge completely. He says that the replacement would “likely” be a 12 inch box culvert. However, because the rest of the structure of the bridge is still in good condition it would be more worth the county’s money to re-do the deck instead of a complete replacement.
Because a bridge replacement would be costly the county would look to help from the Iowa Department of Transportation for funding. For this to happen the county would have to get the bridge re-inspected (has to be a rating of 60 or worst to qualify). Then Loots would have to amend the five year plan to include this bridge.
This process could take six months to a year in which the bridge would also remain closed. By only repairing the deck the bridge will last for “many, many years” on a more timely repair.
Loots says the project should last about two weeks in which the bridge will remained closed.
Featured photo of Bridge 39 courtesy of County Engineer Ben Loots.