State Route 599 (SR 599) is a state highway and freeway in King County, Washington, United States. It is located entirely within the city of Tukwila and travels northwest along the Duwamish River between junctions with Interstate 5 (I-5) and SR 99. The freeway has one intermediate exit and follows the

Central Link The 1Line, formerly Central Link, is a light rail line in Seattle, Washington, United States, and part of Sound Transit's Link light rail system. It serves 19 stations in the cities of Seattle, SeaTac, and Tukwila, traveling nearly between ...

light rail line.

Route description

SR 599 is long and travels on a four-lane freeway located entirely within the city of Tukwila in suburban King County. It begins at a

Y interchange In the field of road transport, an interchange (American English) or a grade-separated junction (British English) is a road junction that uses grade separations to allow for the movement of traffic between two or more roadways or highways, usi ...

with

I-5 Interstate 5 (I-5) is the main north–south Interstate Highway on the West Coast of the United States, running largely parallel to the Pacific coast of the contiguous U.S. from Mexico to Canada. It travels through the states of Californi ...

near Foster Memorial Park, approximately north of the

Southcenter Mall Westfield Southcenter, formerly known as Southcenter Mall, is a shopping mall located in Tukwila, Washington, United States. Owned by Unibail-Rodamco-Westfield, it is the largest shopping center in Washington state and the Pacific Northwest. The ...

and the terminus of Interstate 405. The interchange lacks connections to the north side of I-5, which are provided by the parallel Interurban Avenue, and has a direct offramp to the

high-occupancy vehicle lane A high-occupancy vehicle lane (also known as an HOV lane, carpool lane, diamond lane, 2+ lane, and transit lane or T2 or T3 lanes) is a restricted traffic lane reserved for the exclusive use of vehicles with a driver and one or more passengers, i ...

s on southbound I-5. The only intermediate junction on SR 599 is a partial cloverleaf interchange at South 133rd Street near several

office park A business park or office park is a designated area of land in which many office buildings are grouped together. These types of developments are often located in suburban areas where land and building costs are more affordable, and are typically ...

s, including the headquarters of

BECU BECU is a credit union originally established to serve employees of Boeing, The Boeing Company. BECU was founded as Fellowship Credit Union in 1935 by 18 Boeing employees, and was named Boeing Employees' Credit Union for much of its history. It ...

. The freeway then travels northwest, following the elevated

light rail tracks to the west and the Duwamish River and the

Green River Trail The Green River Trail is a pedestrian and bicycle trail in King County, Washington, USA. It runs along the banks of the Duwamish and Green Rivers, crossing the river several times on bridges.King County Metro King County Metro, officially the King County Metro Transit Department and often shortened to Metro, is the public transit authority of King County, Washington, which includes the city of Seattle. It is the eighth-largest transit bus agency in t ...

bus base, which has a direct onramp to the southbound freeway, and crosses under the light rail tracks at East Marginal Way South. The freeway turns west and intersects Tukwila International Boulevard, which marks the end of SR 599 and where SR 99 resumes. SR 99 continues northwest along the freeway and into

Seattle Seattle ( ) is a seaport city on the West Coast of the United States. It is the seat of King County, Washington. With a 2020 population of 737,015, it is the largest city in both the state of Washington and the Pacific Northwest regio ...

on West Marginal Way. SR 599 is maintained by the

Washington State Department of Transportation The Washington State Department of Transportation (WSDOT or WashDOT, both ) is a governmental agency that constructs, maintains, and regulates the use of transportation infrastructure in the U.S. state of Washington. Established in 1905, it is ...

(WSDOT) and is designated as a minor route of the National Highway System. WSDOT conducts an annual survey of average traffic volume on the state highway system that is measured in terms of

average annual daily traffic Annual average daily traffic, abbreviated AADT, is a measure used primarily in transportation planning, transportation engineering and retail location selection. Traditionally, it is the total volume of vehicle traffic of a highway or road for a ...

, finding in 2016 that approximately 44,000 vehicles use SR 599.

History

SR 599 became a state highway in 1971, but had been part of Washington's older highway system ( Primary and Secondary Highways) from 1957 to 1970. The highway, then known as PSH 1 WM, or West Marginal Branch, was built during the 1960s. When it was completed and opened to traffic in June 1968, U.S. Route 99 (US 99) was about to be removed from the system, so when I-5 was completed up to Tukwila, US 99 switched to the route of SR 599. Later on, the current route of SR 599 became known as US 99T (Temporary) and later SR 99T in 1964. In 1971, the highway became SR 599. SR 181 was temporarily routed alongside the freeway on Interurban Avenue until 1971.

Exit list

References

External links

Highways of Washington State
{{State highways in Washington related to I-5 599 U.S. Route 99 Freeways in the United States Transportation in King County, Washington