If trains are running slower wouldn't that mean that delays should be expected? I don't think the extra time needed is built into the schedule. (It would be interesting to know how much additional time it takes an average Blue Line train to travel end to end when the restrictions are in effect.)
Service Alert: MAX running slower in high speed sections throughout areaTriMet sent this bulletin at 08/11/2014 01:23 PM PDT
Temps are now above 90 throughout the area, so MAX delays are possible as trains run slower in high speed sections to not damage wires, rails.
In 95+ temperatures, WES trains will also run slower – no more than 30 mph.
Also, I know that message is probably canned and doesn't take into account delays that are happening due to other issues like the turn backs in the Lloyd District, but 10 minutes later: