page_title: Interstate 5 in Washington
section_title: Major projects and expansions
hierarchical_section_title: Interstate 5 in Washington / History / Major projects and expansions
caption_attribution_description: Looking south on Interstate 5 in Everett, Washington, approaching the SR 99 / SR 526 / SR 527 junction.
context_page_description: Interstate 5 is an Interstate Highway on the West Coast of the United States, serving as the region's primary north–south route. It travels 277 miles across the state of Washington, running from the Oregon state border at Vancouver, through the Puget Sound region, and to the Canadian border at Blaine. Within the Seattle metropolitan area, the freeway connects the cities of Tacoma, Seattle, and Everett.
  I-5 is the only interstate to traverse the whole state from north to south and is Washington's busiest highway, with an average of 274,000 vehicles traveling on it through Downtown Seattle on a typical day. The segment in Downtown Seattle is also among the widest freeways in the United States, at 13 lanes, and includes a set of express lanes that reverse direction depending on time of the day. Most of the freeway is four lanes in rural areas and six to eight lanes in suburban areas, utilizing a set of high-occupancy vehicle lanes in the latter. I-5 also has three related auxiliary Interstates in the state, I-205, I-405, and I-705, as well as several designated business routes and state routes.
context_section_description: The First Hill Improvement Club and architect Paul Thiry led a campaign in 1961 to reconnect areas of Seattle severed by the freeway with lids that would house parks, parking garages, and other buildings through leased air rights. The lid proposal was approved in October 1969 with funding split between the local government, state government, the Forward Thrust bonds program, and a private developer. Landscape architects Lawrence Halprin and Angela Danadjieva were selected to design the park lid and adjoining parking garages, which would incorporate Brutalist elements and a series of waterfalls.
  The 5.5-acre (2.2 ha) Freeway Park opened on July 4, 1976, incorporating pedestrian and open spaces between Seneca and University streets that continued up the northwest slope of First Hill. The Washington State Convention and Trade Center was constructed north of Freeway Park over a section of I-5 and opened in 1988. Part of the convention center complex was designed by Danadjieva as a continuation of Freeway Park, while the main structure rested on a series of trusses over I-5. In 2019, the Seattle city government approved funding for a feasibility study for an expanded downtown lid after lobbying from a grassroots campaign. The I-5 Colonnade, a 7.5-acre (30,000 m²) mountain bike park, opened in 2007 under an elevated section of the freeway between Eastlake and Capitol Hill.
  WSDOT began installing ramp meters in 1981 to address worsening onramp congestion on I-5 from Seattle to Mountlake Terrace. The first set of 16 ramp meters were activated on September 30, 1981, with a computer system controlling entry at 5–15 second increments; some ramps also had un-metered bypass lanes for transit and three-person carpools. The state's first set of HOV lanes opened in August 1983 for use by buses and vehicles with three or more occupants on the Northgate–Mountlake Terrace section of I-5. By the late 1980s, the 36 miles (58 km) of HOV lanes had reduced average travel times on I-5 by four minutes despite an 86 percent increase in traffic volumes. The HOV lanes were extended north to Lynnwood in 1996 and southern Everett by the end of the decade, when the carpool minimum was lowered to two people per vehicle.
  In the 1970s, the state government began planning extensive rebuilding of the oldest sections of I-5 to meet newer Interstate standards and eliminate design issues. The 6.5-mile (10.5 km), four-lane section through Tumwater, Olympia, and Lacey was rebuilt in the late 1980s at a cost of $150 million (equivalent to $290 million in 2018 dollars). The freeway project was completed with an expansion to six lanes, six rebuilt interchanges, a new bridge for Capitol Way, and improved landscaping. The existing Pacific Avenue interchange near the Tacoma Dome was expanded in the 1980s to accommodate I-705, a new spur freeway traveling north to downtown Tacoma.
  The rebuilding of the three-mile (4.8 km) Vancouver section was completed in August 1983 at a cost of $40 million (equivalent to $86.5 million in 2018 dollars). It included widening the freeway to six lanes, new interchanges with SR 14 and SR 500, relocation of railroad tracks, and the replacement of several overpasses. An additional expansion project on I-5 through Vancouver and Hazel Dell was completed in 2001, replacing the original overpasses and adding a southbound HOV lane. The HOV lane was later removed in 2005 after drivers complained about increased travel times for single-occupant vehicles. A second widening project, completed in 2006, added two lanes on a from Hazel Dell to the I-205 interchange in Salmon Creek, where a new ramp to Northeast 139th Street was later opened in 2014.
  In April 2003, the state legislature passed the Nickel Funding Package, which enacted a five-cent gas tax increase to fund $4.2 billion in transportation projects (equivalent to $5.62 billion in 2018 dollars) that were rejected in an earlier public referendum. The program funded several projects to widen and modernize sections of I-5, including new interchanges in Clark County and the extension of HOV lane
caption: An expanded section of I-5 in Everett, featuring HOV lanes and sound walls
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