travelwp Loc: New Jersey

There are a number of videos that suggest that this thermite process was used in the World Trade Center.

rehess Loc: South Bend, Indiana, USA

Unfortunately, burning jet fuel creates enough heat to undo the process??

Big Bill Loc: Phoenix, AZ

Actually, it was named for weight per yard, not per foot.

https://www.google.com/search?q=rail+weright+per+yard&ie=utf-8&oe=utf-8#q=rail+weight+per+yard

Big Bill Loc: Phoenix, AZ

It was, but today's welded rail deals with expansion/contraction by pretty much forbidding it.
The rail is laid at a neutral temperature, depending on the location. On long tangents (straight sections) this can be a problem, but on curves the rail will move slightly to allow the change in length. Not much, but a little. The railbed is, of course, designed to handle it.
Of course, that's the simple explanation.

Wally Phyfe

Expansion and contraction is still an issue, with welded joints being pulled apart, or rails getting out of alignment due to either one, but it is apparently easier to deal with than all the damage caused by the rolling stock hitting the expansion joints, both to the rails and the trains running on them.

watrmn Loc: Iowa

FYI--From 1977 to 1992, I was employed at a grain, feed, fert & chem elevator in n/w Iowa. We shipped 50, 75, & 100 car unit grain trains.
In the early 1980's part of the rail was replaced with ribbon rail (rr). The rr was 1/4 mile in length, then had welded joints done manual by the work crew.
This work was done in the summer, as ass't mgr I normally worked in the office, so with slack season I used our trackmobile to deliver a car load of rail plates to the work location. In watching the crew, as the weld took place, I found they took a rail temperature...then used a 3.5 h.p. b/s engine with hydraulics to stretch the 1/4 mile section based on the rail temp.
I asked the crew if the rail contraction in cold temp (can get to -20 or -30 below in north Iowa) would likely split the rail. The response was, if so it is easier to repair than a rail blown due to expansion.

FRENCHY Loc: Stone Mountain , Ga

Now I understand why there was no click clack when I rode the TGV a while back (7-8 years ) great technology !!!

Thanks Jerry

DickC Loc: NE Washington state

Very nice, I had no idea this is how they did it!! Thanks for sharing Jerry.

Ka2azman Loc: Tucson, Az

The iron they use in rails today is the same iron mixture that they have used in the past. So expansion/contraction is the same problem. After much scientific study, the information that they have received, is that; they can use 1/4 mile welded rail and the problem with expansion and contraction is pretty much under control.

The rail is welded at the factory and put on special cars that hold 1/4 mile rail and take to the sight where it is to be laid, and by special machines pulled off and laid next to the rail being changed. The rest of the laying of the rail is all done by special various machines. Cut the wood ties, removing them and then jamming in with concrete ties, kick out of the way the old rail and pull in the new 1/4 mile rail. The various machines doing this is sitting on the rail as it does these things. It aligns the final gauge. Then men put in new spring holders that hold the rail to the concrete ties (no spikes).Then a machine tamps the stone under the ties to level it.

Concrete ties are twice as expensive as wooden ones but last twice as long. The real savings comes from maintenance. With wooden ties and spikes the RR needed to continually check and re-hammer (man power)in the spikes often because expansion and contraction and vibration of the weight of the trains would lift out the spikes. The concrete ties use spring type wedges (holders) for the rail that allow for E and C and do not loosen. A section of track had men assigned just to spike the ties. Now they run a machine with one man on board, that reads the rails for broken rail and watches for problems with the new spring system and sees over many more miles a day and reports problems for one crew doing the work that the area of 3-4 crews would do.

The welding seen here is mostly for broken rail and special locations where 1/4 mile rail is inappropriate. Their is a bolted joint every 1/4 mile.

Also there are special crews that only set straight rail as well as special crews that only set rail on curves for 1/4 mile rail.

They also repair rail in any temperature. But they carefully take note where they do repairs and in the spring (for repairs in the winter) they will (after mathematical formula) remove a specific amount to allow for expansion; as well as add a specific amount for pieces laid in the summer for the coming contraction in the fall.

DavidPhares Loc: Chandler, Arizona

Two things jumped out at me as I watched the video: (1) these guys do not have any hair on their heads (I wonder why? Work related?), and (2) No eye protection. One guy had some but they were high on his head not protecting his eyes. What would the union say?

Just an observation.