Inspectors to take a deep look at all 3 miles of the Robertson Tunnel during the first two weeks of February
Overnight inspections of TriMet’s Robertson Tunnel are coming in early February as part of our ongoing commitment to maintaining a safe, reliable and resilient transit system.
Work is scheduled nightly, Feb. 1-12, between 10 p.m. and 4 a.m. While crews will be able to perform the inspections without disrupting MAX service, TriMet will temporarily adjust service nightly from 10 p.m. through the end of service. During this period, when fewer people are riding, MAX trains will share a single track through the tunnel. One platform of the Washington Park MAX Station will be closed, and riders will be directed to the open platform serving both eastbound and westbound trains.
Opened in 1998 as part of TriMet’s Westside MAX Extension project, the Robertson Tunnel is the gateway for MAX Blue and Red Line trains traveling between Downtown Portland and the westside suburbs.
Every four years, the tunnel undergoes regular structural inspections, with more detailed inspections conducted on a longer cycle. This upcoming effort builds on previous inspections by taking a closer look at areas identified for follow-up. It’s also an opportunity for inspectors to look at areas requiring specialized access. State-of-good-repair projects like this help ensure that our transit infrastructure, including our 60-mile MAX system, can support riders and the community for decades to come.
A closer look at the Robertson Tunnel
The Robertson Tunnel is a valuable part of our region’s transit network, with more than 11,000 trips made through it on an average weekday. Regular inspections, combined with tunnel upgrades – such as the Robertson Tunnel MAX Improvements Project, completed in fall 2025 – are essential for maintaining the tunnel as a safe and reliable means of travel.
During the inspection, crews will survey the full length of the Robertson Tunnel and key tunnel features, including ventilation shafts and emergency stairways near Washington Park. Engineers will also conduct targeted geotechnical work to better understand the long-term conditions inside the tunnel.
The overnight schedule allows crews to safely inspect areas near the tunnel ceiling and other critical infrastructure with minimal impact on our service. Overhead power will be shut off only when required and restored before the start of regular morning service.
Fast facts: The Robertson Tunnel
- It includes the deepest transit station in North America
The Washington Park MAX Station, located at the bottom of the tunnel, sits roughly 260 feet below the surface. This makes it the deepest transit station on the continent and the third deepest in the world. High-speed elevators are required to connect the platform to the park, making for an ear-popping journey.
- Despite its depth, it has cellular service
Cellular service is available throughout the tunnel, ensuring riders remain connected even deep beneath the West Hills. TriMet has worked with wireless carriers to install infrastructure within the tunnel to support voice calls, text messaging and mobile data, so riders can communicate and access information during their trips.
- It’s the longest rail tunnel in Oregon
Not only is the Robertson Tunnel Oregon’s longest rail tunnel at roughly 3 miles, it’s also the state’s longest tunnel overall. At its opening in 1998, it was celebrated as an engineering feat, with major construction taking three years and using a specialized piece of equipment: a 278-foot-long hard-rock tunnel boring machine.
- It seamlessly connects two distinctive parts of the region
Completed as the heart of the Westside MAX Extension, the tunnel links Downtown Portland to Beaverton and Hillsboro, providing riders with a direct route beneath forested hills and through volcanic rock. Even with a stop halfway through the trip (Washington Park MAX Station), it takes less time to travel between Goose Hollow/SW Jefferson MAX Station and Sunset Transit Center by MAX than by automobile during peak commuting hours.
- It’s critical for reliability
Beyond shortening travel times between Downtown Portland and the westside, the Robertson Tunnel is weather-protected and grade-separated, making it a dependable, high-speed part of the system. It’s a reliable alternative to the often-busy U.S. 26, helping people travel safely during extreme weather and at times when roads are congested.
Designed for growth, maintained for longevity
At nearly 30 years old, the Robertson Tunnel remains one of the most important connectors in TriMet’s 533-square-mile service area.
The tunnel was first used by the MAX Blue Line starting in 1998. In 2003, the MAX Red Line extension opened, adding more service to Beaverton, while the Better Red MAX Extension and Reliability Project, completed in 2024, extended the Red Line 10 stations into Hillsboro. Over the years, the westside MAX expansions have underscored the tunnel’s ongoing importance and value. It’s been a driver of growth and development.
Maintaining a state of good repair is essential to keeping the region’s transit system safe and dependable. By proactively inspecting and addressing our infrastructure needs, we can prevent unexpected disruptions and extend the life of critical parts of the system that keep you moving every day.