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Photo of the bridge.
Ames Lake Trestle Bridge No. 1320A.


Map showing location of Ames Lake Trestle Bridge.
The bridge crosses Ames Creek on Ames Lake-Carnation Road NE, in rural unincorporated King County between Redmond and Carnation.

Latest update

June 17, 2021

Our engineers are 60 percent complete with the final project design of the replacement bridge. King County is on schedule to start this project in mid-2023. The next public meeting about the project is scheduled for mid-2022.

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Desk 206-263-1189
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Project overview

This project replaces the 96-year-old Ames Lake Bridge with a wider structure and straighter bridge approaches. The improvements are designed to increase sight distance for drivers and provide a safe, unrestricted crossing for trucks and vehicles of all sizes. In addition, the new bridge will be designed to have less environmental impact on Ames Creek and the surrounding wetlands.

The new bridge will be built in the same location as the existing bridge and have no weight restrictions. The road will be closed for the duration of the new bridge construction and traffic must use a detour route. King County will return for a second open house in June 2022 and construction is set to begin in mid-2023. The new bridge should be complete in mid-2024.

Why is King County replacing the bridge?

The Ames Lake Trestle Bridge was built nearly 100 years ago and was originally designed with narrow lanes for much smaller vehicles compared with what we see on the road today. The bridge has a posted weight restriction for specific large trucks and specialized hauling vehicles. Replacing the bridge will provide a safer, unrestricted crossing for the community.

The original timber piles that support the deck are decaying. Over time, the poor condition of the piles could prohibit large trucks and emergency vehicles from crossing, which eventually would require the bridge to be shut down completely.

Project schedule

King County selected a preferred alternative for a replacement bridge, with construction projected to begin in 2023. The preliminary estimated total project cost is $15 million. This project is funded through the King County Capital Improvement Program and the Road Services Division Operating Budget.

Ames Lake Trestle Bridge project schedule

Bridge access for residents and emergency vehicles will be maintained throughout construction. Construction activities will include demolition, concrete pouring, and crane lifts. After the new bridge is opened to traffic, crews will continue low impact restoration work including plantings and site clean-up.

Selected bridge design: Alternative 3B

Selected Design Alternative 3B.

Alternative 3B overview

  • The roadway will be closed to traffic during demolition of the existing bridge and construction of the new bridge.

  • Traffic will use a detour route for the duration of the new bridge construction.

  • All project construction work will comply with terms and conditions set by our partner permitting agencies. King County will follow best practices to avoid negative environmental effects to the stream and other natural surroundings and keep the road open to traffic during construction.

Advantages

  • EASIER TO BUILD: Locating new bridge in the same place as the existing bridge requires less ground shoring and leveling (grading). It also minimizes the size of retaining walls that will be required.

  • PERMANENT BRIDGE FOUNDATION: Built outside of wetlands and Ames Creek.

  • LOWEST CONSTRUCTION COST: Will offer significant cost savings due to the small project footprint and absence of a temporary bridge.

  • LOWEST CONSTRUCTION DURATION: Much faster construction times with no temporary bridge, minimal ground shoring and leveling, and no adjacent traffic.

  • BETTER WORKER SAFETY: Removing traffic near work zones creates a safer work environment.

  • ENVIRONMENTALLY FRIENDLY: The smaller project footprint requires less tree removal and environmental disturbances.

Photos

Ames Lake Trestle Bridge signs.
Vehicle weight restriction signs for the Ames Lake Trestle Bridge.
Under the Ames Lake Bridge.
View of the timber support piles under the bridge.

Frequently-asked questions

The Ames Lake Trestle Bridge was built more than 90 years ago and was originally designed with narrow lanes for much smaller vehicles compared with what we see on the road today. The bridge has a posted weight restriction for specific large trucks and specialized hauling vehicles. Replacing the bridge will provide a safer, unrestricted crossing for the community.

The original timber piles that support the deck are decaying. Over time, the poor condition of the piles could prohibit large trucks and emergency vehicles from crossing, which eventually would require the bridge to be shut down completely.
The new design removes vehicle weight restrictions and improves sight distance by widening and straightening the road. A wider and straighter road helps users on the bridge, and those coming out of adjacent driveways, to see farther down the road. In addition, the new bridge will be designed to have less environmental impact on Ames Creek and the surrounding wetlands.
The bridge crosses Ames Creek on Ames Lake-Carnation Road NE, in rural unincorporated King County between Redmond and Carnation.
Approximately 1,900 vehicles and 70 trucks cross the bridge every day. It is a County-designated snow route. Ames Lake-Carnation Road NE serves a growing population of single-family homes, farm and forest lands.
Yes. The bridge remains safe for passenger cars and trucks. The County restricts specific heavy trucks and specialized hauling vehicles, and the limits are posted near the bridge. These heavy vehicles will continue to be restricted until the new bridge is complete.

King County will continue to inspect and maintain the existing bridge regularly to ensure it is safe to use.
Bridge weight restrictions. Yes, there are.

Current weight limits include:
Type 3: 21 tons
Type 3-S2: 34 tons

Single-unit vehicles:
3 axles or fewer: 21 tons
4 axles: 19 tons
5 axles: 22 tons
6 axles: 25 tons
7 axles: 28 tons

King County regularly inspects the bridges it is responsible for maintaining. If new restrictions are required based on these inspections and bridge load rating analysis, a notice will be posted on the bridge. The County will also note any new restrictions on the Bridge Weight Restrictions website.
The project will replace the bridge in the same location on Ames Lake-Carnation Road NE.
No. The new bridge will be built to current standards and will not have vehicle weight or size restrictions.
Travelers will use a detour route during construction. A temporary bridge will not be built for use during construction.

Bridge access for residents and emergency vehicles will be maintained throughout construction. Of the three bridge design alternatives under consideration, one of them would involve building a one-lane temporary bridge to keep traffic moving along the road while construction is underway. Other alternatives would maintain traffic on the existing bridge while the new bridge is constructed next to it. There will be short-term full closures for certain construction activities, such as delivery and placement of bridge beams. Local access for residences will be maintained.
Travelers will use a detour route during construction. A temporary bridge will not be built for use during construction. Bridge access for residents and emergency vehicles will be maintained throughout construction. The roadway will be closed to traffic during demolition of the existing bridge and construction of the new bridge.
The preliminary estimated total project cost is $15 million.
The King County Council adopted $12.7 million in funding within the Road Services Division 6-year Capital Improvement Program during the 2019 – 2020 biennial budget process. Additional funds for this project come from the Road Services Division Operating Budget.
The project will remove, transport, and dispose of the existing creosote-treated timber piles at an approved disposal facility.
Contact us

24/7 Road Helpline: 206-477-8100 or 1-800-527-6237

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Twitter: @KCRoads