TriMet warns of potential MAX train delays during Portland heat wave

PORTLAND, Ore. (KOIN) – With temperatures expected to reach the triple digits in the first major heat wave of the season, TriMet officials warn passengers they could experience delays through the weekend.

MAX trains may reduce speeds to 35 mph if temperatures top 100 degrees due to an overhead wiring system made of copper, which is sensitive to heat. This could result in up to 30 minutes in delays.

“We’ve made improvements on all MAX lines so that slowdowns shouldn’t be required while temperatures are in the 90s, but when we’re dealing with triple-digit heat, we won’t operate MAX trains above 35 mph,” TriMet spokesperson Mark Miller said.

Copper wires expand and sag when temperatures increase, and counterweights have been placed in areas to help keep the wires taut. However, in extreme heat, those counterweights can sometimes touch the ground, according to TriMet.

Transit officials have been working to replace the cast-iron counterweights with thinner round ones, allowing counterweights “more space to drop before the overhead power wires start to sag.”

Meanwhile, buses are expected to run on schedule unless impacted by local traffic, though officials say “heat-related issues are possible for buses running for long hours in extreme heat.”

TriMet has not enacted its extreme weather fare policy, which would allow passengers to ride to and from emergency shelters – even if they are unable to pay the regular bus fare. Transit officials say this decision depends on whether Multnomah County declares a state of emergency or begins to open extreme weather shelters.

“We have been in close communication with Multnomah County,” Miller said. “Once they determine if or when extreme weather shelters open, TriMet leadership will determine if or when we’ll put our extreme weather fare policy into effect.”

Stay with KOIN 6 News as our coverage of the heat dome continues.