How come the MAX has to slow down every time the temperature gets over 90 degrees? They have light rail in Phoenix, and it's much hotter there.

—Heat Miser

This question is a perennial summertime favorite with local newsfolk in search of a fun, fluffy, "betcha didn't know"-type feature. (Technically, I suppose, this column is also a fun, fluffy feature—except I say "fuck" all the time, which is probably why those newsfolk pull down 80 bills a year and I get a bowl of beef jerky and a bed behind the Linotype machine.)

The standard answer is that heat makes the rails expand. When they've expanded lengthwise as far as they can, they start to buckle sideways. This can create little jogs in the track called "sun kinks," which will derail the train if it's going too fast.

And that's usually that. Real Ed Murrow types may dig deeper to ask: What about cities where it's even hotter? The answer is that those cities' rail systems work within an overall higher temperature range, so it's no worse than here.

The question no one asks is: What about cities that get way colder than us, but also way hotter, like the hell on earth of my childhood, St. Louis? Their light rail doesn't buckle. Neither does Seattle's, and they have the same weather as us.

It turns out you can totally build track that resists sun kinks! Anchoring the ties in concrete instead of resting them in gravel pretty much takes care of it. We didn't do that, presumably because it doesn't get hot enough often enough in Portland to justify the expense.

Now that it seems to be getting hotter, though, TriMet has a pilot program to anchor rails on the Red Line, and it seems to be working. If results are good, the transit agency will extend it, which could save everyone half an hour every day. I would tell you more, but I have to go fight a rat for the last piece of jerky.

Questions? Send them to dr.know@wweek.com.