Interstate 605 (I-605) is the popular moniker given to several proposals for a new

auxiliary Interstate Highway Auxiliary Interstate Highways (also called three-digit Interstate Highways) are a supplemental subset of the freeways within the Interstate Highway System of the United States. Auxiliary routes are generally classified as spur routes, which con ...

bypassing

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 ...

and

I-405 Interstate 405 may refer to: * Interstate 405 (California), a bypass of Los Angeles, California * Interstate 405 (Oregon) Interstate 405 (I-405), also known as the Stadium Freeway No. 61, is a short north–south Interstate Highway in Portl ...

in the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sove ...

of Washington. Proposals have been heard from since the 1960s, including highways connecting from I-5 all the way to the Canada–US border, and some just between I-5 and

I-90 Interstate 90 (I-90) is an east–west transcontinental freeway and the longest Interstate Highway in the United States at . It begins in Seattle, Washington, and travels through the Pacific Northwest, Mountain West, Great Plains, Midwest, ...

. 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) has no projects designated I-605 at this time. However, some I-605 proposals have included State Route 18, which has been partially constructed as a freeway.

Proposals

Some of the first plans for a new

Interstate Highway The Dwight D. Eisenhower National System of Interstate and Defense Highways, commonly known as the Interstate Highway System, is a network of controlled-access highways that forms part of the National Highway System in the United States. T ...

freeway, bypassing I-405, surfaced in 1965 while the highway was still under construction. The first proposal was to create a new highway between I-405 and the west banks of

Lake Sammamish Lake Sammamish is a freshwater lake east of Seattle in King County, Washington, United States. The lake is long and wide, with a maximum depth of and a surface area of . It lies east of Lake Washington and west of the Sammamish Plateau, a ...

. Residents however forced the highway to the east banks of the lake after voicing their concerns. Residents on the east side of the lake voiced similar concerns and the plan was later dropped. While the moniker of "I-605" was applied to the proposal, in official studies it was only referred to as the Auburn–Bothell Highway or by the provisional designation of Primary State Highway 19 (PSH 19). In 1998, the Washington State Legislature ordered a $500,000 study to investigate the benefits of extending SR 18 north to Everett through the Snoqualmie Valley. The plan was dropped as the study found that on average only five minutes would be saved over current routes. In 2002, Bellevue Square owner Kemper Freeman, Jr. made his support known for a new freeway linking

Snohomish County Snohomish County () is a county located in the U.S. state of Washington. With a population of 827,957 as of the 2020 census, it is the third-most populous county in Washington, after nearby King and Pierce counties, and the 75th-most populo ...

via the Snoqualmie Valley. Another $500,000 study was ordered in 2003 by the legislature, creating a new

commerce corridor A supercorridor is a proposed new type of transportation infrastructure in the United States. A supercorridor would use swaths of land up to 1,200 feet (370 m) wide to carry parallel links of freeways, rails, and utility lines. The freeway porti ...

to link Lewis County in the south to the Canada–US border in the north. However the study showed that a highway existing north of

was not economically feasible. The study proposed a

toll road A toll road, also known as a turnpike or tollway, is a public or private road (almost always a controlled-access highway in the present day) for which a fee (or '' toll'') is assessed for passage. It is a form of road pricing typically implemen ...

only for trucks, since the presence of passenger cars would discourage truck drivers from using the new alternate route. The highway was estimated to cost between $13.5 and $19 billion.

Related projects

The state currently has no plans to build I-605. However, the SR 18 corridor is part of most I-605 proposals. WSDOT has widened most of SR 18 between I-5 and Hobart to full freeway standards, while the remainder is a two-lane mountainous highway with truck lanes on uphill segments. WSDOT once proposed to creating a full limited-access freeway for the remainder, but updated preliminary plans would upgrade it to a four-lane divided highway, with

right-in/right-out Right-in/right-out (RIRO) and left-in/left-out (LILO) refer to a type of three-way road intersection where turning movements of vehicles are restricted. A RIRO permits only right turns and a LILO permits only left turns. "Right-in" and "left-in" r ...

at Tiger Mountain and a

diverging diamond interchange A diverging diamond interchange (DDI), also called a double crossover diamond interchange (DCD), is a subset of diamond interchange in which the opposing directions of travel on the non-freeway road cross each other on either side of the inte ...

at I-90. While SR 18 has been a part of most I-605 proposals, it only bypasses the Greater Seattle area on the southern and eastern sides.

References

External links

* {{3di, 5 05-6 (Washington) Transportation in Seattle Cancelled highway projects in the United States 05-6 (Washington)

Proposals

Related projects

See also

References

Further reading

External links