TriMet will close a segment of the MAX Blue Line light rail system east of the Gateway/NE 99th Ave Transit Center from April 27th to May 10th for track maintenance while replacing and upgrading equipment along its East Burnside Street route. The East Burnside MAX Improvements Project will require riders to use shuttle buses along the affected segment during the scheduled work. MAX service reopens between the Gateway/NE 99th Ave Transit Center and E 172nd Ave stations on May 4th, while riders east of that station will continue to use shuttle buses between the E 172nd Ave and Cleveland Ave MAX stations through May 10th.
Crews will work on some of the oldest tracks in TriMet’s light rail system, replacing road crossing panels and wood railroad ties with concrete versions on the easternmost segment. Crossing panels support vehicle tires as they perpendicularly cross the train tracks, keeping the road surface at the same level as the top edge of the rail. This design minimizes the bumps for drivers crossing the track, but panel wear and settling over decades requires reconstruction at the Northwest Eleven Mile Avenue crossing. Similarly, railroad ties wear over time with diminishing support of the tracks. The new concrete ties offer a longer lifespan and better stability, improving the ride for MAX users.
Overhead work included in this project begins to address a problem experienced by the MAX system when temperatures exceed component limits. A dual-wire catenary system delivers 750 Volt of DC power to the MAX trains that use an upward-extending pantograph device to make contact with the over-track energized wire. The catenary wire must remain taut for dependable power delivery to moving MAX trains below. During hot days exceeding 90 degrees Fahrenheit, the copper wire stretches through thermal expansion and could sag. To address this, TriMet uses hanging weights at the end of the cables draped over pulleys to remove the horizontal slack by pulling the excess cable down. However, on the hottest days, the one-ton of stacked weights can travel to its lowest point and fail to keep the catenary wire taut, prompting MAX operators to pause the lines or slow travel speeds. Crews will replace the old weighted system with Tensorex mechanical tensioners that will not have the same limitations as hanging metal plates and keep Portland’s light rail moving even in extreme heat waves.
Installing automatic mechanical tensioners in this segment is just one phase of building a resilient light rail service for a changing climate. TriMet plans to replace about 8,000 feet of overhead wires elsewhere in the system and may expand Tensorex use. During this closure, crews will also clean and refresh inactive stations. Riders should expect shuttle buses running in place of trains approximately every 10 minutes for most of the day. However, people should plan on their travel through the disrupted area taking up to 30 minutes. Crews working in the roadway will need to reduce traffic at Northwest Eleven Mile Avenue and East Burnside Street and completely close the crossing during two overnight stints from 11 p.m. to 3 a.m. When completed, MAX Blue Line riders should have a more reliable journey through this segment, and drivers crossing the track will likely notice a smoother ride.
