The goal of the Puget Sound Gateway Program can be summed up simply: moving freight from point A to point B. The Washington State Department of Transportation (WSDOT) is in the midst of two projects that will provide essential connections to the Ports of Tacoma and Seattle, as well as SeaTac Airport. The two projects involve SR 509 and SR 167 and together make up the Puget Sound Gateway Program.The building of both state routes began in the late 1960’s with the goal of paralleling and connecting to I-5. In the early 1970’s, the projects petered out due to a lack of funds, cities incorporating in the originally planned path, and people’s altered vision for land usage. Neither route was completed, stopping miles short of I-5.

By the 1990’s, planning studies were initiated to develop updated ways to complete the connection between the routes and I-5. There were starts and stops in both corridors from that point forward. In 2010, WSDOT completed toll feasibility studies for the routes. Another study was completed that suggested combining the completion of both state routes into one package. The study was submitted to the Washington State Legislature in 2013, and the program received funding in 2015.

Combining the state routes into one program was a significant step as they could be done in tandem rather than competing against each other for funding and attention. “Because we’re delivering each state route in parallel fashion, it keeps the improvements associated with each port equitable,” says John White, WSDOT’s Puget Sound Gateway Administrator, who is responsible for overseeing delivery of the program.

Delivering both projects together is sensible. The work needed is similar, they share a common theme, and there’s lots of value in delivering it as one package as it maximizes efficiencies in planning, environmental review, design, and construction.

The SR 509 project involves extending the route by building two miles of new tolled expressway to connect with I-5. WSDOT will also add collector-distributor lanes to I-5, build a tunnel under I-5 to connect to the Kent distribution centers, and develop bicycle and pedestrian facilities.

The SR 167 project will build six new miles of new tolled expressway. Four miles of the route will extend the existing highway to connect to I-5. Two miles of the new route will then connect I-5 to the Port of Tacoma and downtown Tacoma. Other elements of the project include developing four new interchanges and bicycle and pedestrian facilities. Finally, the project will include an extensive 175-acre environmental restoration program.

Work on each state route is being split into three stages, and each stage can stand alone in terms of a specific set of improvements. According to White, the stages are being built in a sequence to match the availability of funding. “With the work being split into three stages, it allows us to match the work up to the money available to us,” says White. “Each project is starting with a smaller piece of work then moves into larger design-build contracts, and they will dovetail into each other.”

WSDOT plans to complete the Puget Sound Gateway Program in 2028. The program is currently on schedule. However, Washington’s budget has been strained by the pandemic and the gas tax, a major source of transportation revenue, dropped significantly. “While some revenue sources appear to be recovering, it is currently unclear if or how the state’s revenue situation might affect the SR 167 and SR 509 Completion Projects,” says Laura Newborn, Communications Manager for WSDOT.

The Puget Sound Gateway Program is approximately a $2 billion program. Funding is coming from four sources. The bulk of the money – $1.6 billion – is coming from the state via the Connecting Washington program. Other sources are local contributions ($130 million), tolling ($180 million), and federal grants, including a $73.6 million Infrastructure For Rebuilding America (INFRA) grant.

The primary element of the initial SR 167 stage is the construction of a new four-lane bridge along a key freight route. It replaces an existing two-lane bridge and provides a 12-foot-wide path for pedestrians and bicycles.

The $40 million design-build contract was let at the end of 2019, though construction began in earnest in the spring of 2020. A key feature of the bridge, which spans I-5 and is a key connector to the Port of Tacoma, are the girders.

At 220 feet long, the pre-cast bridge girders are at the upper limits of what’s been utilized in the United States and around the world. There are 10 bridge girders, and each one is 9 feet tall and weighs 231,000 pounds. Typically, transporting bridge girders of this size is too complex. “The reason we’re able to use these girders is because the manufacturer is located in close proximity to the contract,” says White. “They’re able to get them to us along a direct route.”

Using these exceptionally long bridge girders will enable WSDOT to avoid widening I-5 and building columns in the median. This is both a savings in terms of time and money and a prime example of why WSDOT decided to go design-build.

“With design-build, we are looking for innovation and betterment of the base design,” says White. “We are hoping that this shows up in terms of a lower bid and in minimizing impacts.”

The contractor is installing the bridge girders over the course of back-to-back nights on one weekend. After that, they’ll need a minimal amount of time for finishing. “Because the work can be completed in an accelerated way, it adds lots of value to the owner and users of I-5,” says White. Keeping the route open is essential due to the amount of traffic.

Other elements of the initial stage of SR 167 include construction of a roundabout connecting the bridge to and from SR 99 and adding additional trail and parking.

The other phases of SR-167 includes some other unique or atypical elements.

One of the interchanges along the project (at I-5 and SR 167) will be a diverging diamond interchange. White views DDIs as a revolution as they are less expensive than other interchange designs and equal in terms of operations. “They have a distinct advantage as they allow for efficient operation within a small footprint,” says White. Given the nature of the traffic volumes and movement, it’s also a good fit for the area.

The four-mile additional section of SR 167 is being built entirely on fill. It’s estimated that the project will require four million cubic yards of fill material. WSDOT is gathering clean fill material from regional projects and stockpiling it until needed. “We’re getting the fill material essentially for free, so within the construction contracts we’re only paying for placement of fill and compaction which is a fraction of what the cost would otherwise be,” says White.

When the Puget Sound Gateway Program is complete, “Critical freight links between the Puget Sound marine ports and the industrial areas of South King and North Pierce counties will bring economic benefits to the Puget Sound region, the state of Washington and beyond,” says Newborn. “Expanding connections to all the ports in the region will ultimately reduce traffic on local roads and highways by completing important new highway connections and providing alternate routes to I-5.”