SR 8 runs east from US 12 in Elma to an interchange with US 101 northwest of Olympia. The route links the city of Elma with Olympia, and intersects only one other highway, SR 108, in McCleary. WSDOT has found that more than 17,000 motorists utilize the road daily at the interchange with US 101 based on average annual daily traffic data. SR 8 starts at an interchange with US 12 near downtown Elma. From the interchange, the expressway goes northeast and starts to parallel the Chehalis River. After crossing the river twice, the highway intersects SR 108, which goes northeast towards Kamilche, west of McCleary. After passing Downtown McCleary, SR 8 has a partial cloverleaf interchange with Mox Chehalis Road. From the interchange, the expressway goes east to form the northern boundary of the Capitol State Forest, and passes Summit Lake. From Summit Lake, the highway turns northeast and merges with US 101 southbound. The entire length of SR 8 is expressway. When combined with US 12 to the west and US 101 to the east, it serves as the primary connection between the Puget Sound region and Washington's Pacific coast.
History
Before the Primary and Secondary system, SR 8 in 1923 was part of a branch of State Road 9, from Elma to Grand Mound. Later, in 1937, the route from Elma to Grand Mound became part of Elma – Grand Mound branch of Primary State Highway 9. PSH 9 EG became SR 8 in 1964 during the 1964 highway renumbering, in which the Washington State Department of Transportation replaced the previous system of Primary and Secondary Highways with a new system called State Routes, which is still in use today. Later in 1967, US 12 was extended from Lewiston, Idaho westward to Aberdeen. It was approved on June 20, 1967, and it replaced the route of US 410, therefore making the highway obsolete. Since US 12 used the all-weather White Pass and SR 8 from Elma to Grand Mound, and US 410 used Chinook Pass, which was closed during the winter, US 12 bypassed US 410 and what is now SR 8. Signs were changed in late December 1967, and the bypassed segments of US 410 became a new SR 8. On June 9, 2007, a tanker fire occurred on SR 8 when a tanker truck with 10,000 gallons of fuel collided with another vehicle and started a fire. The fire caused SR 8 to close for a couple of hours except for the westbound left lane, which crews used to get oil out of the soil underneath the highway. During the Winter 2007 storm, a slope that held up SR 8 was eroded by floodwaters. The slope, located on SR 8 west of the US 101 interchange, and is scheduled to begin this season and last 2 months. In 2010, WSDOT aims to rebuild the columns that support the SR 8/US 101 interchange and reduce the risk of failure in an earthquake, such as the 2001 Nisqually earthquake.
