Denny School Road closed July 14-31 for bridge repair project

LEBANON — The Linn County Road Department plans to close Denny School Road between Sand Ridge Road and Airport Drive from Monday, July 14 through Thursday, July 31.

The closure is necessary to allow the Road Department’s Bridge Maintenance Division to perform repairs on a bridge spanning Oak Creek.

Linn County is, and has historically been, a timber-producing county. Road Department Operations Manager Kevin Hamilton said that most of Linn County’s bridges contain timber components in the substructure of the bridge.

“Substructure components include the piles (vertical columns that transfer weight to the ground), and the caps which span the piles and support the slabs,” Hamilton said. “Deck slabs are the part of the bridge superstructure that span the creek. Headwalls act as a retaining wall to keep the road base in place.”

Hamilton noted that “Although timber makes an excellent building material, it is subject to decay over time. Decay within substructure components can lead to weight restrictions on bridges, lane restrictions, and even road closures if not found and corrected early enough.”

The bridge on Denny School Road, number 707-162 in the County’s inventory, currently has a weight restriction on it due to having timber caps. Weight restrictions are posted on signs at the affected bridge, and typically at intersections on approach to the affected bridge.

Timber caps are replaced with steel components called W-beams, which is short for wide-flanged beams. Crew members weld reinforcing gussets into the forms to strengthen them. This work is all subject to the oversight of the Road Department’s Engineering Division who ensure that repairs are performed to meet or exceed structural engineering standards for these components.

The work being performed this July on 707-162 will replace three timber caps and two headwalls, and will also include repairs to two piles. The caps on this bridge are exceptionally long due to the width of the road and the geometry of the bridge relative to Oak Creek.

“This work will remove existing weight restrictions, but more importantly will prevent unexpected restrictions or closures from occurring in the future. Being on the busiest county-maintained road in Linn County, it is important to anticipate and avoid any such long-term delays,” Hamilton said.  

The City of Lebanon is currently performing work which includes a road closure on Airport Drive within the city limits. This project presented an opportunity to schedule the County’s work to coincide with the traffic disruption already occurring.

While the road is closed for the bridge repair, other maintenance divisions will take advantage of the road closure to perform maintenance activities in the area. A road maintenance crew will crack-seal Airport Drive from the city limits to Sand Ridge Road.

The Traffic Control Division will also use the opportunity to re-stripe the road without disrupting traffic to do so. Additionally, the Road Department has requested an inmate work crew to collect garbage along the roadway during this time.