European Railroad Discussion > Expansion joints on a mountain railway

Expansion joints are usually found in the track on certain bridges where the differential thermal expansion of the rails and structure can't be controlled by other techniques. Here's a situation where they are employed on a mountain railway.

While watching a cab ride video on the Rhätische Bahn/Rhaetian Railway (RhB) Albula line in south-eastern Switzerland, the presenter (Paolo) indicated that the section of the line from Tiefencastel to Surava is built on unstable ground and is sliding downhill at a rate of 1.2 meters/year.

This section of both the road and rail line needs constant maintenance to deal with this slow landslide.

The attached picture shows one of two track expansion joints in the section. You will also note the gravel ballast berm is quite a bit higher than normal, and you can also see some catenary poles are slightly out of vertical alignment with each other.

Ray

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Very interesting -- thank you. Mountainside instability is a real issue in the Alps, and engineers and geotechnicians employ a variety of strategies to monitor for it and to mitigate its effects. Here's a reference link to a very good webpage on this issue from the European Geosciences Union (EGU): https://blogs.egu.eu/divisions/nh/2019/04/29/alpine-rock-instability-events-and-mountain-permafrost/

I notice two thick cables running down the center of the track. Are they some type of sensor or warning tool for track movement, somewhat akin to slide fences?

MC

ironmtn Wrote:
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>
> I notice two thick cables running down the center
> of the track. Are they some type of sensor or
> warning tool for track movement.......

I think they are a low-resistance bypass around the 'slip joint' for the AC electrification return current.  It is possible they also could be used for track circuit purposes, but I didn't think the RhB used track circuits for train detection on the open line due to their widespread use of steel ties;  for example, it looks like the first few ties at the bottom of the photo, before the concrete [ ? ] ones begin, are steel.

SZ
 

Makes sense, particularly with the steel ties, which I had noticed. Thank you.

MC

The tapered sliding joints are high wearing and have to be replaced constantly.....