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Ames Lake Trestle Bridge Replacement Project

Project anticipated to begin in spring 2024

Two engineers inspect the Ames Lake bridge from the bucket of an under-bridge-inspection-truck (UBIT) truck.

Two engineers inspect the Ames Lake bridge from the bucket of an under-bridge-inspection-truck (UBIT) truck. The bridge will be replaced in 2024. 

Status update

King County intends to advertise to contractors in December 2023, and construction is anticipated to start in March or April 2024. The next community meeting about the project will be held online in early 2024, check back in December for the exact date. 

During construction, Ames Lake-Carnation Road, between W. Snoqualmie Valley Road NE and NE 52nd Street, will be closed at the bridge location. The work will take approximately eight (8) months.

Download Project Flyer (3.56MB)

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Project overview

This project replaces the 100-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 host an online community meeting about this project in early 2024 and construction is anticipated to begin in March 2024. The new bridge should be complete in late fall 2024.

Ames bridge project locatoin map

The bridge crosses Ames Creek on Ames Lake-Carnation Road NE, in rural unincorporated King County between Redmond and Carnation.

Why is King County replacing the bridge?

The Ames Lake Trestle Bridge was built 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 timeline

Winter 2024: 

  • Online community meeting will be held in February, the date is to be announced.
  • Utility relocation work at the bridge may require temporary lane restrictions or single-day full road closures ahead of construction. We will provide at least 48-hours advance notice when the bridge needs to be closed. 

Spring and summer 2024:

  • The project is expected to begin in spring and will take approximately eight (8) months to complete.
  • During construction, Ames Lake-Carnation Road, between W. Snoqualmie Valley Road NE and NE 52nd Street, will be closed to all vehicles, bicycles and pedestrians at the bridge location. 
  • There will be no posted detour as there are many alternate routes available in the area. All traffic, including emergency vehicles and school buses, must use an alternate route for the entire eight-month-long construction period. The project team will notify Google Maps of the closure. 

Fall 2024: The new bridge is anticipated to reopen to all by the end of December. 

 

Map of alternate routes to use during construction

The roads shown in purple above are all the alternate routes that can be used when Ames Lake Bridge is under construction. There is no official detour route for this project.

What to expect during construction 

The project team will protect the trees in the creek and will work to prevent dust and dirt caused by construction work from spreading in the air.  In addition, people living near the work area might experience the following while the bridge is being removed and replaced:

  • Noise and odor from sawcutting, jackhammers, excavators, generators and pumps.
  • Trucks hauling materials to and from the construction site. 
  • Large construction cranes in the roadway. 

After the new bridge is opened to traffic, crews will continue low impact restoration work including plantings and site clean-up.

 

Future bridge layout

The new Ames Lake Bridge will be wider, straighter and safer than the existing bridge. There also will be improved visibility for oncoming traffic. All of these improvements will allow those coming out of adjacent driveways to see farther down the road. 

 The new bridge will be in the same place as the existing bridge. Building it in the same spot requires less ground shoring and leveling (grading). It also minimizes the size of the retaining walls that will be required.

Environmental improvements

The new bridge is designed to minimize and prevent environmental impacts on Ames Creek and the surrounding wetlands.
This project will:

  • Improve fish and wildlife habitat.
  • Improve water quality.
  • Reduce erosion.
 

Project budget

The estimated cost of this project is $10.8 million. It is funded through the local King County sources. 
 

Photos

Frequently asked questions

The Ames Lake Trestle Bridge was built 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.
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.
We decided not to include a temporary bridge due to cost and traffic impact. The new bridge will cost significant less to build due to the small project footprint and absence of a temporary bridge. The county will be able to build the bridge much faster because it will be closed to traffic.

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.
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.
No. There will not be any access for drivers, pedestrians or emergency vehicles when the new bridge is under construction. The project does not plan to offer a signed detour route because there are several north-south alternate routes in the area that drivers can use to get around when this section of Ames Lake Carnation Road NE is closed to traffic.
The preliminary estimated total project cost is $10.8 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.
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