Why do electrified trains have to obey a slower speed limit on hot days? I always thought it is because the overhead wires expand and droop more (from catenary action). Thus, the pantograph is more likely to snap a wire. Or, is it because the track expands and a derailment is more likely at higher speed? Or, other? Please explain.
Extreme heat can affect Amtrak infrastructure. For instance, if tracks get too hot, they can develop a kink; or if overhead power wires—called a catenary system—get too hot, they can sag, Anderson shares. When the temperature of the rails reaches a certain threshold, Amtrak requires that locomotive engineers operate trains at slower speeds than usual, in order to spot potential hazards and adjust course accordingly.
Stranger
A little of both I’d say.
I know what the Amtrak spokesperson meant, but saying that a railroad engineer will “spot hazards and adjust course” sounds so wrong. Not much swerving in the railroad biz.
Reminds me of one of my favorite books from childhood. “Stay on the track no matter what!”
I probably had that book too. So cute.
In railroad-speak, a derailment is “train on the ground”. Which also strikes me funny. They neither fly nor float, so where else would they be? But “on the ground” of course is different from “on the tracks” where they do belong.
“Phrasing!”
I’ve been on trains that had to go slow because it was too hot and the track might buckle (it was diesel, no catenary) and on at least one that had to go slow because it was too cold and the track might crack. On one cold day, the train was not allowed north of Albany and we were bussed.
I think a lot of this is due to poor quality rails.
Or a management decision to accept slow running and failures on some small x number of days per year rather than WAG doubling the cost of trackage built to operate healthily at any temp between e.g. -60C and +60C.
Bingo! Thanks!
Surprised they don’t have some sort of temperature expansion/contraction device to counter the droop of the power cables. For rails it might be too difficult or impractical.
In the UK I see line tensioners like this:
A lot of the catenary on the northeast corridor between New York City and Washington DC was installed in the 1930s, and hasn’t been upgraded since, so the tensioning system is rudimentary at best. North of NYC there’s newer stuff, and some other sections were replaced/upgraded, but overall it’s pretty outdated.
In the UK, they used to run a pilot / scout engine up the tracks before the mail express, so that the mail express could run full speed in winter.
“Course” of action?