This week there will be single lane closures for geotechnical investigations on the Historic Columbia River Highway near the Stark Street Bridge. Expect brief traffic delays.
Geotechnical work begins Tuesday, Oct. 8 and will continue through Thursday, Oct. 10. Each day, single lane closures will be during daytime hours, from roughly 7:00 a.m. to 7:00 p.m. on the Historic Columbia River Highway. Crews are studying the rocks and soil beneath the road’s surface.
Background
Multnomah County is actively working with a contractor to design emergency repairs needed to reopen the Stark Street Bridge. The bridge is expected to be closed for several months.
Resources for residents
Every Friday throughout the duration of these emergency repairs, Multnomah County will post an update on repair progress to: https://www.multco.us/roads/week-roads. For questions related to the repairs, contact:
Ken Bossen,
Multnomah County Transportation Road Maintenance Supervisor
Detours
Vehicles will be rerouted to use the Sandy River Bridge in Troutdale.
Initial closure
On Tuesday, Sept. 17, the Stark Street Bridge in the Columbia River Gorge closed due to a supporting stone wall that partially collapsed. Since then, the bridge has been closed. The County started work the minute the bridge wall collapse was discovered and has been working non-stop with engineers, biologists, historical resource experts and a contractor to evaluate the situation and figure out the best way to repair the bridge. The partial collapse was caused by a series of crashes by vehicles and large trucks over the last decade that weakened the supporting wall.
What we know so far
The Historic Columbia River Highway entrance to the Stark Street Bridge where the wall collapsed is structurally compromised, is unsafe to put vehicles on and will have to be replaced. The County also discovered 6 to 8-inch holes in the bridge deck, which were easier to detect with traffic off the bridge. The County also found that the opposite side retaining wall is also in danger of collapse .
What are we doing right now
Multnomah County secured an under-deck unit to fix the holes in the deck, but the collapsed support wall is much more complicated and will take a lot longer to repair.
The County met on site with its designer, contractor and the Oregon Department of Transportation (the agency that operates the Historic Columbia River Highway) at the end of the bridge where the wall collapsed. Based on preliminary inspections, extensive reconstruction of the bridge approach will be required before traffic can be allowed back onto the bridge. Repairs could take up to six months.
Work to reconstruct the approach will start with geotechnical investigations in the Historic Columbia River Highway to ensure that repair work does not impact the highway. That work will reduce the highway to one lane for periods of time in the next few weeks.
What we are doing longer term
The County was already working on the preliminary steps to replace or significantly rehabilitate the bridge because of its condition and lack of capacity. In the future, the County will need to make more permanent repairs either as part of a bridge replacement or through a project to build a new permanent approach.
Multnomah County maintains the Stark Street Bridge on the Sandy River. For project information, visit: link.multco.us/stark-street-bridge. For information on County bridges, visit: https://www.multco.us/bridges.