I-5 - Chamber Way - Stage 2

Project news

Interstate 5 or I-5, serves as the primary connecting highway on the west coast, running parallel to the Pacific Coast through California, Oregon, and Washington, and is the only highway in the nation to touch both the Canadian and Mexico borders.

To keep people and goods moving through Washington State, this project will focus on reducing congestion and improving safety on the I-5 corridor between the Chamber Way interchange and the State Route 6 interchange, in Lewis County. 

Needs & benefits

Why is WSDOT looking to reduce congestion and improve safety and mobility at the I-5 Chamber Way interchange?

Anyone who travels along this stretch of highway is all too familiar with traffic backups and delays during peak travel times as a result of increased traffic using two through-lanes on either side of the Interstate. Continued growth and development in the area will contribute to increased traffic backups and related crashes if no improvements are made.

In an effort to improve safety and trip reliability along the corridor, the Washington State Department of Transportation developed a series of improvements along I-5 in Chehalis and at Chamber Way. During our online open house hosted in June 2020, people who live, walk, bike or drive through this area told us that their top priorities for this corridor are safety, reliable travel, and improved options to walk, bike or use public transit.

Study Area

The I-5 Chamber Way - Stage 2 project improvements to I-5 in Lewis County between the cities of Chehalis and Centralia.​

The general study limits may include the following:

  • I-5 between SR 6/Main Street in Chehalis and Mellen Street in Centralia 
  • Chamber Way between Louisiana Avenue and National Avenue in Chehalis 
  • West Street between Louisiana Avenue and State Avenue in Chehalis 
  • SR 6/Main Street between Riverside Drive and State Avenue in Chehalis 

End Results

The information gathered during our June 2020 online open house helped to identify the following primary community concerns within the study area:

  • Safety:  This project will help improve safety by working to reduce congestion related crashes:  
    • On I-5 between Parkland Drive and Harrison Avenue, collisions have increased by nearly 40 percent during peak commute times from 2014 to 2018.
    • There were a total of 1,146 crashes in the study area between 2014 and 2018, and two-thirds of the collisions in the study area were rear-end and side-impact crashes, which are generally associated with congested traffic conditions. 
  • Mobility: This project will help improve mobility within the project limits for all travelers, including freight, general highway traffic, local traffic, public transit, pedestrians and bicyclists.

Planning Phase Results 

During the June 2020 online open house, we shared conceptual designs to address these safety and mobility concerns and categorized the project improvements as either a primary, secondary, or supplemental strategies on our Project Design Concepts page. 

We heard from respondents that their top priorities included congestion/wait times, safety and limited transportation options (i.e., transit, safe biking lanes/walking routes). 

We also received the following feedback regarding the conceptual designs:

  • Issues/Feedback
    • Disconnected and limited transportation options (i.e., transit, safe biking lanes/walking routes).
    • Many respondents were interested in strategies that included adding more than a single additional lane on I-5 to increase traffic capacity. 
    • Generally, respondents liked the strategies that involved roundabouts to improve traffic flow, however, requested the project provide clear markings and other design features to help drivers use roundabouts correctly.
    • Avoid impacts to wetlands.
  • Resulting project design revision
    • Incorporated bike lanes and sidewalks into designs for local streets for connectivity to existing multi-modal facilities.
    • The answer to reducing congestion is not always as simple as adding more lanes to the highway. Currently, because it would cause significant impacts to nearby roads, utilities and buildings adjacent to the interstate, providing more than a single lane of widening in each direction is not fiscally viable. To maximize our existing infrastructure and help alleviate congestion, this project will add a low-cost solution of adaptive ramp meters at the north and southbound 13th Street, SR 6, Chamber Way and Mellen Street ramps,  and the southbound Harrison Avenue ramp. Ramp meters help break up groups of the traffic entering the freeway keeping traffic on I-5 moving.
    • Increased roundabout travel lane widths and incorporated curbs that oversized loads and freight vehicles can drive on to easily navigate  roundabouts at Chamber Way and SR 6 interchanges.
    • The West Street overpass design option evaluation focused on the importance of reducing impacts to adjacent wetlands and the selected preferred alternative has only minor wetland impacts.

WSDOT used this information to further collaborate with project stakeholders to incorporate this feedback and further refine project priorities to select the preferred design options that would best address community needs. Following is a summary of these preferred design options for Chamber Way interchange, SR 6 interchange, and West Street Overcrossing.


Work to date in the Planning Phase has accomplished the following project milestones:

  • 2019 – 2020: Collaborated with project stakeholders to develop conceptual designs
  • Summer 2020: Received extensive public input through public online houses, mailers, flyers, emails and phone calls  
  • Fall 2020 – Spring 2021: Refined design concepts, conduct alternative assessments and select preferred alternatives.

Timelines for the combination of improvements vary based on the amount of engineering work, right of way and environmental permitting needed for each. To make the most of available funds and implement improvements as quickly as possible, we will construct these improvements in phases. Evaluation of traffic data and future modeling shows that installation of adaptive ramp meters at the on-ramps to I-5 is an effective way to improve safety and mobility along the corridor and can be implemented fairly quickly. Construction of adaptive meters at 13th Street, SR 6, Chamber Way, Mellen Street and southbound Harrison Avenue ramps could begin as early as 2023. 

This is a Connecting Washington funding package with $83 million in available construction and right of way funding assigned to this project. To make the most of available funds and implement improvements as quickly as possible, we’ll construct these improvements in phases. 


Financial Data for PIN 400521A
Funding Source Amount ($ in thousands)
2003 Gas Tax (Nickel Funding) $0
2005 Gas Tax (TPA) $0
Pre-Existing Funds (PEF) $5
CWA $82,995
Total $83,000


Colin Newell 
WSDOT Project Engineer  
(360) 740-8600

Celeste Dimichina
WSDOT Communications
(360) 905-2057

I-5 - Chamber Way - Phase 2 - project location near Chehalis in Lewis County