By Luke Carothers

Interstate 5 runs roughly parallel to the West Coast of the United States, linking its largest cities from the southern border with Mexico to the northern border with Canada.  It carries a tremendous amount of freight annually, and connects regional and national markets with international ones in Mexico, Canada, and the Pacific.  However, despite the importance of this transportation corridor, several critical connections are in need of renovation, repair, or even replacement.  One of these critical connections is the Interstate 5 Bridge across the Columbia River, which links the states of Oregon and Washington.

While Interstate 5 was created in 1956 as a part of the Interstate Highway System, its construction made use of existing infrastructure.  One such piece of infrastructure was the existing Interstate Bridge over the Columbia River, which was opened in 1917.  In 1958, a second twin bridge was constructed, and, with its opening, each bridge carried one-way traffic.  As the surrounding communities have grown in the last half century, the Interstate 5 Bridge has come to represent a vital link for people, goods, and services.  However, this vital link has become outdated, and the problems that stem from the structure’s age are driving the conversation to replace the aging piece of infrastructure. 

Courtesy of the Interstate Bridge Replacement program

The outdated state of this bridge has serious ramifications for the people who rely on it for their day-to-day lives.  There are a significant number of safety issues that arise from the bridge’s design and age.  Currently, the bridge is one of the highest crash locations in Oregon’s interstate system, and it averages 7-10 hours of congestion during the morning and evening commutes.  These problems largely arise from the bridge’s lack of shoulders, lifts, and closely spaced interchanges.  To further add to the congestion, the bridge lies between the Port of Portland and the Port of Vancouver, which means that over 13,500 trucks crossed the bridge in 2019, representing just under 10 percent of daily traffic.  The issues of freight congestion will only be exacerbated by future growth, and experts predict that freight tonnage will double by 2040.  Further stress is added by the fact that there is currently no high capacity transit connecting Portland and Vancouver.  While there is a walking and biking path on either side of the bridge, its small 3.5 foot width is not capable of safely supporting any meaningful amount of foot or bicycle traffic. 

The conversation to replace the bridge has been going on for almost 25 years.  Previous efforts to update the structure failed in 2014 because the Washington state legislature declined to take up the funding package.  However, despite this setback, the problems posed by the bridge were only getting worse.  With the Portland-Vancouver area’s average growth of just over 13 percent, the problems that exist as a result of these outdated structures will only be exacerbated by a bigger population.  Furthermore, the current design is a lift bridge built on timber piles in a silty river, which poses significant problems if it were to experience an earthquake.  The lift bridge style is so outdated that there are less than 20 still in service throughout the United States.

This need was recognized in 2019 when Governor Kate Brown of Oregon and Governor Jay Inslee of Washington agreed to create the Interstate Bridge Replacement Program (IBR).  The goal in creating the IBR program is to replace the Interstate Bridge over the Columbia River with a modern, seismically resistant, multimodal structure.  In doing so, this corridor will see improved mobility for people, goods, and services.  Furthermore, the IBR program seeks to address the displacement of historically marginalized communities, placing a massive emphasis on equity through community engagement.  Greg Johnson, the IBR program administrator, notes the importance of not only understanding the historical inequity that was built into our interstate highway system, but also in identifying the communities that need to be heard from as we update these key pieces of infrastructure for a new generation.  

This particular stretch of I-5 between Portland and Vancouver has a history fraught with inequity.  This stretch of highway was planned and constructed directly through a predominantly Black neighborhood, Albina.  In turn, many of the neighborhood’s residents were forced to move, relocating throughout the Portland-Vancouver metroplex.  This inequity is only compounded when these same residents are subject to the safety and financial issues that come as a result of the aging piece of infrastructure.  Johnson believes that by addressing the concerns of the groups that were disproportionately affected by the original construction of I-5, the new iteration of the infrastructure will be planned and built on the basis of equity. One of the defining pieces of the IBR program is a focus on the surrounding community, particularly in placing an emphasis on equity and addressing concerns with how communities are affected by climate change.  

Courtesy of the Interstate Bridge Replacement program

To do this, Johnson and the IBR program created an Equity Advisory Group as well as the positions of Principle Equity Officer and Principle Climate Officer that continually assess how the project can improve from an equity and sustainability perspective.  The Equity Advisory Group, which meets once a month, consists of equity professionals from across the region who look at the project’s processes and outcomes to ensure equity and community outreach who make recommendations to ensure equity in both processes and outcomes for the program. With a 5-7 year timeline of construction on the new bridge as well as a $3-5 billion investment, Johnson sees this as the perfect opportunity to plan and design the bridge in a way that will significantly improve the lives of those in the community.

Currently, one of the biggest challenges facing these underserved communities is a lack of access to reliable public transit crossing the river.  As the area’s population increases, so too do the issues of congestion. According to the IBR program, the population in the program’s area has grown by 17 percent since 2000, including a 49 percent increase in BIPOC population.  The IBR program’s plan is to build a new, multimodal facility that includes high-capacity transit (HCT).  This not only provides an option to those who would otherwise drive, but it serves as a critical piece of infrastructure for the 15 percent of households in the area who do not own a vehicle.  The decision to include high capacity transit as a main feature of the project both alleviates congestion in the corridor and provides a much needed piece of infrastructure for the communities who are disproportionately affected by the current lack of reliable public transit options across the bridge.

The IBR program’s plans for the new facility are also focused on making sure it can withstand a significant seismic event.  According to Johnson, the most likely seismic event will come from the Cascadia Subduction Zone, which is roughly 70 years overdue for a significant movement.  The current bridges’ wooden pilings set in silty soil as well as its lift design make it likely that the structure will collapse during the next significant earthquake.

This new seismically-resistant, multimodal facility will have not only a modern design that improves safety and travel reliability, but it will also support other modes of transportation.  In doing so, this new facility not only lessens the risk of bridge failure and driving accidents, but also in reducing congestion and idling time for trucks and smaller vehicles.  This has the dual impacts of improving the quality of life for the people who use the bridge as well as reducing emissions that stem from traffic congestion.             

The IBR program is currently in the environmental and community engagement phases of the project, and intends to begin construction on the new facility in 2025.


Luke Carothers is the Editor for Civil + Structural Engineer Media. If you want us to cover your project or want to feature your own article, he can be reached at lcarothers@zweiggroup.com.  

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