The Nulle Road / Friday Creek Bridge No. 106 is a 76-foot-long structure consisting of four 19-foot channel beam girders on timber piles and caps. Given the weight restrictions on the bridge and the additional traffic it will see during the upcoming North Lake Samish Road Bridge No. 107 Replacement Project, Public Works looked for ways to rehabilitate this structure.
After looking at multiple options as part of a study by Trantech Engineering, we decided to use carbon fiber reinforced polymer (CFRP) wraps to strengthen the structure while adding minimal additional dead load.
Construction was completed by Strider Construction in the summer of 2023 and consisted of epoxy injecting cracks, repairing concrete spalls, and reinforcing the girders with CFRP wraps. In addition, Ritter Dirt & Asphalt removed the existing chip seal layer from the bridge deck, and the bridge approaches were ground out and repaved to reduce impact loading to the structure. The project allowed the weight restrictions to be removed, and the bridge is now open to all legal loads.
This was considered a pilot project and a cost-effective way to strengthen and extend the service life of these types of channel beams, which are very common in our County bridge inventory. We will watch this bridge to see how it performs and will likely utilize this approach in future rehabilitation projects.