Portland Train Speed Limited by Extreme Heat

When temperatures hit 100 degrees, the city’s two train systems face challenges that force them to slow their speeds or stop operations altogether.

2 minute read

July 8, 2024, 12:00 PM PDT

By Diana Ionescu @aworkoffiction


White and blue TriMet MAX light rail train on street in Portland, Oregon.

jovannig / Adobe Stock

Portland’s MAX trains must slow down after temperatures hit 100 degrees, reports Anthony Macuk for KGW.

According to Macuk, “TriMet has upgraded the system in recent years to maintain full speed at higher temperatures, but there's still an upper limit.” After 100 degrees, MAX trains will slow down to a top speed of 35 miles per hour, while WES trains will top out at 40 mph.

At 105 degrees, the WES trains stop running. If temperatures get that high, TriMet may adjust or suspend service on MAX trains, but that decision is made based on conditions throughout the system and out of consideration for the safety of riders and employees.

As Macuk explains, “MAX trains are powered by overhead wires, which have to be kept taut so the train's pantograph arm can maintain steady contact. But the wires are made of copper, which expands when heated and can cause sagging.” If the sagging causes the lines to sink too low, trains have to slow down or stop entirely.

WES trains face a different problem, one that could impact Amtrak and other train systems as well. “TriMet's WES trains are diesel-powered and run on Portland & Western freight rail tracks with no overhead wires, but they can still get tripped up by heat waves because the high temperatures can also cause the steel rails to expand and temporarily deform — a phenomenon called ‘sun kinks’ — making it unsafe to drive trains over them at full speed.” 

Friday, July 5, 2024 in KGW

portrait of professional woman

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching. Mary G., Urban Planner

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching.

Mary G., Urban Planner

Get top-rated, practical training

Close-up of "Apartment for rent" sign in red text on black background in front of blurred building

Trump Administration Could Effectively End Housing Voucher Program

Federal officials are eyeing major cuts to the Section 8 program that helps millions of low-income households pay rent.

April 21, 2025 - Housing Wire

Logo for Planetizen Federal Action Tracker with black and white image of U.S. Capitol with water ripple overlay.

Planetizen Federal Action Tracker

A weekly monitor of how Trump’s orders and actions are impacting planners and planning in America.

April 30, 2025 - Diana Ionescu

Ken Jennings stands in front of Snohomish County Community Transit bus.

Ken Jennings Launches Transit Web Series

The Jeopardy champ wants you to ride public transit.

April 20, 2025 - Streetsblog USA

Close-up of white panel at top of school bus with "100% electric" black text.

Driving Equity and Clean Air: California Invests in Greener School Transportation

California has awarded $500 million to fund 1,000 zero-emission school buses and chargers for educational agencies as part of its effort to reduce pollution, improve student health, and accelerate the transition to clean transportation.

April 30 - California Air Resources Board

Aerial view of Freeway Park cap park over I-5 interstate freeway in Seattle, Washington at night.

Congress Moves to End Reconnecting Communities and Related Grants

The House Transportation and Infrastructure Committee moved to rescind funding for the Neighborhood Equity and Access program, which funds highway removals, freeway caps, transit projects, pedestrian infrastructure, and more.

April 30 - Streetsblog USA

"No Thru Traffic - Open Streets Restaurants" sign in New York City during Covid-19 pandemic.

From Throughway to Public Space: Taking Back the American Street

How the Covid-19 pandemic taught us new ways to reclaim city streets from cars.

April 30 - Next City