PORTLAND, Ore. — A heat wave means delays on some, but not all TriMet MAX trains. The delays are up to 15 minutes on the Orange, Yellow and Green lines when the temperature is between 90 and 100 degrees.
Delays climb to 30 minutes or more for all MAX trains when we reach 100 degrees.
The reason is that metal expands when it gets hot, and steel rails can expand by several inches in hot weather. Copper overhead lines that power the trains expand too, and sag.
TriMet improved a counter weight system on the Red and Blue lines so the lines don't sag as much. That means they'll be able handle heat better.
“So they could still keep that tension on that line so we could run trains at speed. And we also put in some anchor ties in some key sections of the rail to keep it from expanding and creating what's called a sun kink,” said TriMet spokesperson Roberta Altstadt.
At this point there is no specific timetable for improving other MAX lines to better handle hotter weather.
But the WES commute train can handle the heat better now, too, thanks to improvements to the rails it runs on, and the installation of a positive train control system.