How do they avoid “clack-clack” sounds on high-speed trains? Are the rails made without gaps? And how do they manage thermal expansion then?

Question

How do they avoid “clack-clack” sounds on high-speed trains? Are the rails made without gaps? And how do they manage thermal expansion then?

In: 1047

Answer 1

I used to work for a large class one railroad in the U.S., specifically in the maintenance of way (track) department.

New rail is CWR (continuous welded rail) and was delivered on a specialized train as the lengths were around 1200-1300 feet each. We called it ribbon rail, as it was quite flexible when being transported, dropped and installed Here’s a link to a video of the train I’m talking about:

[https://www.youtube.com/watch?v=O4kC262exiw](https://www.youtube.com/watch?v=O4kC262exiw)

Here’s a video of a production crew installing new rail:

[https://youtu.be/MNpUD6iLWNY?t=461](https://youtu.be/MNpUD6iLWNY?t=461)

For the area of the country we were working in, engineering had designated a Target Neutral Temperature of 95 degrees fahrenheit , which means that if the rail was installed and anchored down at that temperature, the track structure would be able to resist both the compressive forces generated by higher temperatures and the tensile forces created by cold (shrinkage… the pool was cold damnit!)

After the new rail is installed, the rail ends will be joined, usually through a process like thermite welding:

[https://www.youtube.com/watch?v=5uxsFglz2ig](https://www.youtube.com/watch?v=5uxsFglz2ig)

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It’s not perfect, time and heavy traffic can cause the rail to “flow” in one direction, potentially leading to excess rail being in an area. If this is not caught and destressed by cutting out a portion of rail you could end up with a “sun kink” or thermal misalignment.

Thermal Misalignment: [https://www.youtube.com/watch?v=_LoXgN1QWZM](https://www.youtube.com/watch?v=_LoXgN1QWZM)

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I know I’ve probably left off a lot of detail, if you have more questions throw them at me. I worked in the track department for 10 years, great job if you love the outdoors, but don’t expect much of a personal life unless you’ve got more seniority than god.