Mhal9000: /used to be a gandy dancer

Hold me closer.

Mhal9000: The engineering term for it is a "thermal misalignment". Modern railroad mainline is almost all CWR or continuous welded rail. Back in the day rail came in standard length sections that was bolted together, thus providing expansion/contraction points when the weather got hot or cold. All those joints require a lot of maintenance though, which is why the jump to CWR was made. Unfortunately you lose all those points of expansion/contraction, so you have to combat it in other ways.
The normal methodology is to lay the CWR at a certain temperature, causing the rail to expand when it's being installed, and locked in with rail anchors or some other form of fastening technology. The track structure can resist compressive forces much easier than expansive, and everything should be good.
What happens in instances like this could be attributed to maintenance, like cutting in a rail plug during the winter and not taking the steps to adjust the rail's temp, or it could just be rail movement over a long period of time, especially around areas such as switches or crossings (or the concrete section as shown in the picture) as they can act like an anchor point. It could also be attributed to poor components of the track structure.
Regardless, this isn't necessarily a rare instance, especially in areas experiencing higher than normal temperatures.

/used to be a gandy dancer
//bonus points if you know what that is w/out googling the term



moose turd pie, eh?
but seriously. yup. hard work leveraging them in...

Mhal9000: The engineering term for it is a "thermal misalignment". Modern railroad mainline is almost all CWR or continuous welded rail. Back in the day rail came in standard length sections that was bolted together, thus providing expansion/contraction points when the weather got hot or cold. All those joints require a lot of maintenance though, which is why the jump to CWR was made. Unfortunately you lose all those points of expansion/contraction, so you have to combat it in other ways.
The normal methodology is to lay the CWR at a certain temperature, causing the rail to expand when it's being installed, and locked in with rail anchors or some other form of fastening technology. The track structure can resist compressive forces much easier than expansive, and everything should be good.
What happens in instances like this could be attributed to maintenance, like cutting in a rail plug during the winter and not taking the steps to adjust the rail's temp, or it could just be rail movement over a long period of time, especially around areas such as switches or crossings (or the concrete section as shown in the picture) as they can act like an anchor point. It could also be attributed to poor components of the track structure.
Regardless, this isn't necessarily a rare instance, especially in areas experiencing higher than normal temperatures.

/used to be a gandy dancer
//bonus points if you know what that is w/out googling the term

I remember the good old days where we'd put a quarter over those gaps (at very specific gaps) and it would make the gates come down. Good times for a young teenager looking to be a pain in the ass. Then we discovered (ok, were taught) that bridging both rails with any good conductor (like speaker wire) would do the same thing but could be done pretty far from the crossing. We caused some mayhem for a few days until the railroad cops chased us off.

/Googling not necessary for me!

Metro / Deadtro continues its ritual un-prosecuted pre-meditated killing of passengers city wide.

Bill_Wick's_Friend: Steel melts at 2600o.

Wake up, sheeple.