CANNON BEACH - The Oregon Department of Transportation has restricted traffic to one lane over the Necanicum River (Black) Bridge on U.S. Highway 26 at milepoint 4.4 as a safety precaution following an inspection by divers Friday morning.
The ODOT divers found that one of the bridge's vertical support footings has been undermined by debris and fast-moving water following the heavy rain over the past six days. A hydraulic scour effect has washed away a portion of the gravel underneath the footing, which could reduce the weight-bearing capacity of the vertical support.
An ODOT design team has developed a repair plan that consists of driving heavy steel supports vertically underneath the bridge into the river bed. A horizontal beam will then be placed across the underside of the bridge - and be held up by the vertical steel supports.
The repair project will begin Saturday morning. The work should be completed by the following weekend.
Flaggers will control traffic across the bridge until repairs are finished. Motorists should expect short delays.