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Duvall Slough Bridge #1136B (NE Woodinville-Duvall Road) Re-Deck Project

Construction and five-week-long road closure in summer 2024

Duvall Slough Bridge.

Both directions of the Duvall Slough bridge on NE Woodinville-Duvall Road (shown above) will close for bridge deck repairs in summer 2024. Photo: Google Maps.

Status update

Construction on this 5-week-long project will start in summer 2024. NE Woodinville-Duvall Road at Duvall Slough Bridge will close to all traffic during construction. King County is coordinating with WSDOT to minimize traffic delays on the detour route (West Snoqualmie Valley Road and State Route 203).

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The Duvall Slough Bridge is located on NE Woodinville-Duvall Road, east of West Snoqualmie Valley Road. King County will remove the top half-inch of worn-out concrete on the bridge deck and replace it with one-and-a-half inches of new concrete. The project also rebuilds both bridge approaches and repairs two bridge expansion joints. This work will protect and extend the life of the bridge for 30 years or longer.

This project goes to construction in summer 2024. The work requires a five-week-long road construction closure on NE Woodinville-Duvall Road between State Route 203 (Main Street/Carnation-Duvall Road) and West Snoqualmie Valley Road. The road must be closed because the bridge is too narrow to keep a lane open and maintain a safe work area. In addition, there cannot be any vibration from traffic when crews repave the concrete or work on the expansion joints.

A signed detour will be provided. The 7-mile-long detour could add an extra 15 minutes of travel time. We understand this is an inconvenience, please consider planning ahead.

Why this project is needed

More than 10,000 vehicles cross the Duvall Slough Bridge on NE Woodinville-Duvall Road every day. Crews have temporarily closed the bridge to repair potholes and patch up cracked concrete many times over the years. The concrete driving surface is now too damaged to rely on short-term repairs. Overlaying the concrete bridge deck, rebuilding the bridge approaches and improving the bridge expansion joints are critical to keeping this vital east-west corridor open to traffic for years to come.

What caused the bridge deck damage?

The 75-year-old concrete deck is cracked, prone to large potholes, and is nearly worn down to the steel rebar in some places. Water seeping through the cracks and thinning concrete continues to make the damage worse.

Why do the expansion joints need to be repaired?

The old expansion joints no longer allow the concrete to expand and contract like it needs to. Repairing the expansion joints will helps prevent cracking by allowing the new concrete re-deck to expand and contract like it should.

Project location

The project is located on NE Woodinville-Duvall Road between West Snoqualmie Valley Road NE and West Snoqualmie River Road NE. Larger view PDF 168KB

Five-week traffic detour during construction

NE Woodinville-Duvall Road is among the most heavily used east-west routes in King County. Crews must close the bridge to all traffic, including emergency response vehicles, to have enough room for a safe work zone. The seven-mile-long detour could add an extra 15 minutes to your trip. Travelers should add plenty of extra travel time through the area when this project is under construction.

Larger view PDF 211KB

Budget and funding sources

The preliminary estimated total project cost is $1.9 million. This project is funded by Federal grants.

Project timeline

  • November 2023 – Advertise to contractors
  • Summer 2024 – Construction
  • August 2024 – Project complete

Frequently asked questions

The entire bridge will be closed to all traffic, including all emergency response vehicles. This means all emergency responders must use the detour to drive around. We will continue to keep emergency responders (Fire, Police, Sheriff) notified of our construction schedule so they can plan ahead.
We will update this website with more information leading up to the start of construction. In the meantime, please contact Broch Bender ( with any questions or concerns.
King County is committed to doing this project during the summer months when school is not in session.
The bridge is too narrow to open a lane of traffic and maintain enough room for construction equipment and crews to do the work. Also, most of the work requires a still, calm surface. Vibration from busy traffic could cause problems with curing concrete and expansion joint repairs.
King County traffic engineers will monitor the detour route throughout the project. They can adjust the traffic signals on the detour route and neighboring roads during busy times to help prevent long delays. We also will coordinate with WSDOT to help prevent any additional full closures on SR 203 (Carnation-Duvall Road) or W. Snoqualmie Valley Road when NE Woodinville-Duvall Road is also closed.
The repairs are expected to last for at least 30 years.
No, King County Road Services did not replace the concrete bridge deck in 2013. Instead, we overlayed the deck with additional concrete and installed a thin protective ‘epoxy aggregate’ (plastic resin mixed with gravel and sand) overlay coating over the bridge deck to help keep the added concrete intact. This type of repair is meant to last between five and ten years. It has been 11 years now. The 2024 bridge re-deck will completely remove the top half-inch of concrete and replace it with one-and-a-half inches of new concrete.
First, crews will use high-intensity water pressure (hydro-demolition) to remove most of the existing concrete deck (approximately 0.5 inches deep, 639-feet long, 24-feet wide). Next, we will overlay the entire length of the deck with new, 1.5-inch-thick concrete on top of the existing steel rebar. Once the concrete is in place, we will modify the expansion joints and rebuild the bridge approaches on both sides of the span to meet the new raised deck height.
Aside from the worn-out concrete bridge deck and corroded expansion joints, all other parts of the Duvall Slough Bridge #1136B are in safe condition. It costs more than $50 million dollars to replace an entire bridge. The repairs we are making in 2024 will cost $1.9 million and will last for at least 30 years.
The Duvall Slough Bridge #1136B is 639 feet long and 24 feet wide.
The bridge is located on NE Woodinville-Duvall Road, one of the busiest corridors in Unincorporated King County. Approximately 9,000 vehicles cross this bridge every day.