The westbound US 2 trestle in Snohomish County is the only direct highway route across the Snohomish River to the Interstate 5 (I-5) corridor in Everett. Due to significant population growth, the westbound trestle is busier and more congested.
In 2018, we began gathering information about evolving traffic patterns, growth and the effect on the westbound trestle. Our study also made a high-level examination of floodplains, wetlands and fish-bearing streams.
A panel of traffic engineers, transit experts, land use planners and elected representatives studied different replacement and improvement options. The study also included initial community engagement with residents and trestle users.
Concepts analyzed
The study started with several dozen concepts. Most were immediately eliminated due to safety concerns or the high cost of rebuilding portions of I-5 to accommodate new or improved US 2 connections. Two emerged as the most practical and were selected for additional evaluation:
- Concept 2: A four-lane trestle with three general purpose lanes and one high occupancy vehicle lane.
- Concept 3: A three-lane trestle with three general purpose lanes, one of which becomes a short HOV/bus bypass lane just prior to the I-5 interchange.
Prior to developing and evaluating these two concepts, project and traffic engineers forecasted the amount of traffic expected on westbound US 2 in year 2040. The forecast used projected population, business growth and transit plans. This includes Community Transit's long-term plans and Sound Transit's planned light rail extension to Everett.
Environmental considerations
The area surrounding the existing trestle presented many challenges. The structure crosses fish-bearing streams, floodplains and wetlands. There may also be cultural resources that will require consultation with local Native American tribes and other agencies. Additional information about environmental considerations is available in the appendices.
Fish bearing streams
Many species of fish including Chinook salmon, chum salmon, coho salmon, pink salmon, bull trout, cutthroat trout and steelhead trout are found throughout the study area between the Snohomish River and SR 204.
Floodplains
Ebey Island is directly under the trestle. The entire island is considered a floodplain. Some areas of the island are considered a floodway. A floodway is the channel of a river or stream and the land next to it that must remain free from obstruction so that a 100-year flood can be carried downstream.
Wetlands
Dozens of wetlands that surround the US 2 trestle must be protected from highway storm runoff during construction. They consisted mostly of swampy or marshy areas with rooted plants and grasses such as cattails, reeds and ferns. Other areas are dominated by woody vegetation from ground level to more than 20 feet tall. The plants found in these areas include willows, alder, white pine, mature red maple and elm trees. There is also an established WSDOT mitigation site near Home Acres Road.
Community engagement
To ensure we heard from community members, we conducted an online open house from Monday, September 14 – Friday, October 16, 2020 to share our findings. An accompanying online survey asked people who use the westbound US 2 trestle and area residents about their experiences on it.
More than 2,200 people took the survey. We asked 17 questions not including demographic questions. The study questions and results are available in the appendices.
Survey highlights
Top three problems with the existing trestle
- More than 58% believe the problem is not enough lanes.
- 53% said population growth has overwhelmed the trestle.
- 45% said the existing ramp to southbound I-5 can't accommodate peak period traffic.
Use of transit, carpooling/vanpooling
- More than 55% said they will not use transit.
- 29% said direct transit service with no or fewer transfers would encourage them to use it or use it more often.
- 26% said a dedicated HOV lane would encourage them to try carpooling or vanpooling.
Paying for a new bridge or improvements
- 41% supported using the existing gas tax.
- 28% did not support using the existing gas tax, user tolls, a Snohomish County tax or a combination.
- 21% chose "other" and added comments stating opposition to tolls or any additional taxes.
Due to the COVID-19 pandemic, we did not hold in-person events or meetings during the community engagement period. We plan to do more community outreach, particularly with limited English-proficiency residents and other under-represented populations, if future phases of the project development receive funding.
The total cost of this study is estimated at $2.2 million, funded by pre-existing state gas tax funds and the 2005 Transportation Partnership Program (TPA).
The study revealed that a new or upgraded trestle with more lanes could only provide a limited near-term benefit, but it would not eliminate westbound congestion. Southbound I-5 through Everett is typically packed with weekday morning commuters. With no improvements on I-5 planned, the backups during peak commute times will begin earlier and last longer. Traffic on a wider trestle would still back up as vehicles slow to squeeze onto a congested I-5 and by 2040, traffic congestion on the trestle would be worse than it is now.
Key takeaways:
- Highway congestion: Increasing the capacity of the westbound trestle does not alleviate congestion during the morning peak hours. Increased demand generated by a larger trestle could not be accommodated by I-5 and resulted in longer travel times across the westbound trestle.
- Three-lane trestle: A three-lane trestle would provide enough room for the traffic expected in 2040 if congestion is addressed on the highway network.
- Managed lanes: Managed lanes such as transit, HOV, express toll, or peak-use shoulder lanes could provide people with an option to bypass congestion and potentially improve conditions on I-5.
- Walk, bike, roll: A long-term solution for the westbound trestle would provide an opportunity to create a valuable active transportation corridor between communities east of the Snohomish River and downtown Everett.
- Mode share: The percentage of HOV and transit vehicles on the corridor during morning commute hours is expected to be less than 9% in 2040. Transit providers would need to include or increase service plans to give people a choice beyond single-occupancy vehicles and ensure service is coordinated with local and regional land use planning.
- Environmental considerations: Environmental conditions are unlikely to serve as key differentiators among trestle alternatives. Potential adverse effects on sensitive areas and requirements to avoid, minimize or mitigate environmental effects will be key considerations in developing a long-term solution.
Further analysis needed
Analysts and elected representatives agree that we need to further evaluate the three-lane concept that includes a transit/HOV lane or managed lane. We will also need to study possible improvements on I-5 to improve the effectiveness of a wider trestle.
