A design for the repair work needed on the Tolt Hill Bridge in Carnation is expected to be complete by the end of the year, King County roads officials announced late Tuesday, Oct. 3. Work on the repairs is projected to begin early next year.
The bridge was closed on an emergency basis June 16 to all traffic, then re-opened to light vehicles only on July 17. Engineers had determined it was safe to allow vehicles of six tons or less on the bridge, as well as bicycles and pedestrians.
The emergency closure followed a series of inspections in recent months, to determine if area bridges met updated Federal Highway Administration load-rating standards. There had been no accidents related to the bridge, or any public safety concerns leading up to the closure.
During the inspections, though, engineers found discrepancies between the measurements of the bridge, built in 2008, and the designs for it. They determined that the design firm had mistakenly transferred the wrong minimum measurements from the design to the plans. The problem was not caught when the $17 million bridge when it opened, because the inspection of the bridge was made against the faulty plan, not the correct original designs.
For project updates, sign up for Road Alert emails on the on the Tolt Hill Bridge Emergency Repairs webpage (http://www.kingcounty.gov/depts/transportation/roads/tolt-bridge.aspx), or follow kcroads on Twitter.