The Westside Express Service (WES) is a commuter rail line in the U.S. state of Oregon serving parts of Washington and Clackamas counties in the Portland metropolitan area.

Owned by TriMet and operated by Portland & Western Railroad (P&W), the line is 14.7 miles (23.7 km) long and travels north–south from Beaverton to Wilsonville along a route just west of Oregon Highway 217 (OR 217) and Interstate 5 (I-5).

[7] This route connected with Southern Pacific's existing west-east West Side branch in Beaverton that provided service to Portland and Hillsboro, and a second route south of Tigard to Cook, which was a junction with the Newberg branch between Lake Oswego and McMinnville.

Both the Southern Pacific and the Oregon Electric (and its successor Burlington Northern) continued to provide freight service on the line until the 1990s when both railroads leased its low-density branches to shortline operators.

Led by Washington County, planning for WES began in 1996, when county officials started working with the cities of Beaverton, Tigard, Tualatin, Wilsonville and Sherwood, as well as government transportation agencies to study the idea of establishing passenger rail service between Beaverton and Wilsonville on the existing Portland & Western line.

Construction began October 23, 2006, in Wilsonville, and a ceremonial "ground-breaking" was held two days later in Tigard,[11] although the project had already started and no dirt was moved.

A distinctive feature of the line is the gauntlet track sections installed at the three intermediate stations (Hall-Nimbus, Tigard and Tualatin).

[16] The feature allows freight trains to swing clear of the high-level platforms at the stops, so that wider cars do not strike them.

[22] In April 2010, the Rail Division of the Oregon Department of Transportation (ODOT) published a study for a potential southern extension of WES from Wilsonville to Salem.

[26] In February 2024, SB 1572 was released, which if passed would require ODOT and other Oregon rail transit agencies to study the possibility of a Salem extension.

[30] Hall/Nimbus Station, the second stop in Beaverton, is served by local TriMet bus lines 76 and 78 and has about 50 park-and-ride spaces.

[30] Wilsonville and Salem-Keizer Transit (Cherriots) currently provide express bus service between the two cities, linking to the rail line.

[33] Other neighboring communities are also expected to use the Wilsonville stop, including Lake Oswego, Donald, Woodburn, and Aurora.

They entered into a 10-year operations and maintenance contract, which includes a trackage rights agreement, in 2007, with a renewal option every five years.

TriMet also leases property near the Wilsonville terminus from P&W, where it built a dedicated maintenance facility for WES.

Originally priced at $4 million each prior to cost overruns, the cars are equipped with places for two mobility devices and two hanging bicycle racks, and have enough space for 139 standing passengers.

[44] The FRA requires all trains operating on heavy rail lines to sound their horns for at least 15 seconds at a minimum level of 96 decibels (from 100 feet (30.5 m)) as they approach crossings.

For the rush hour-only schedule used when WES began operation, that meant over a thousand blasts a week along its route, starting as early as 5:30 am.

[44] Complaints about the noise caused TriMet to replace the original 102-decibel (from 100 feet (30.5 m)) Leslie RS3K horns for a fleet-wide cost of $5,000.

Equipment failures and periodic maintenance on the agency's Colorado Railcar DMUs resulted in TriMet substituting buses for some runs on several occasions since the service began.

To provide backup equipment for the line, TriMet purchased two Budd Rail Diesel Cars (RDCs) from the Alaska Railroad in 2009.

[51] They were originally expected to enter service on the WES line in fall 2018, after the completion of a few modifications,[51] but this was subsequently delayed to sometime in 2021[53] and later indefinitely.