Fish Plates

[Rhinochugger]

Maybe yes, maybe not.... the question is: what's prototypical? From mainline to out-of-the-way short lines, I've seen numerous variations in rail coupling.

Expansion: US mainlines utilize continuous welded rail. How they compensate for expansion is a mystery to me.

Of course curves let most of the expansion go, they move.

long straight track is still a wonder to me. Must be laid with enough gap to compensate, but how about 1/4 mile of welded rail?

The answer is at what temperature the rail is laid at (pretty high) and sometimes the rail does have to be cut, shortened and re-welded.

How Do Railroads Deal With Thermal Expansion? | Worldwide Rails

How do railroads deal with thermal expansion? Railroads deal with thermal expansion by heating the rail prior to installation. Therefore, the rail

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Greg

Modern, continuously welded track is laid pre-stretched and therefore expansion only becomes a problem when the ambient temperature exceeds the design parameter.

In the UK, track is laid pre-stretched to the equivalent length of 83 degrees Fahrenheit - above that temperature, train speeds are reduced so that drivers can rely on line of sight for any problems.

Two questions in my mind:

1. How did they arrive at 83 degrees for the UK?
2. More importantly, how does the rail stay stretched? What stops it creeping back? In building, thermal movement goes both ways with contraction being the most damaging.

 

[dunnyrail]

Modern, continuously welded track is laid pre-stretched and therefore expansion only becomes a problem when the ambient temperature exceeds the design parameter.

In the UK, track is laid pre-stretched to the equivalent length of 83 degrees Fahrenheit - above that temperature, train speeds are reduced so that drivers can rely on line of sight for any problems.

Two questions in my mind:

1. How did they arrive at 83 degrees for the UK?
2. More importantly, how does the rail stay stretched? What stops it creeping back? In building, thermal movement goes both ways with contraction being the most damaging.

The theory is the the rail being held in tight by clips expands in part the other ways to a lesser extent than would be applicable than along the length. I think in part this causes stresses that can be guilty of causing broken rails greater than may have applied to 60ft jointed track, though here the joints were vulnerable. Clearly modern CWR (continuous welded rail) is cheeper to maintain and is being adopted by many preserved railways, though not quite so technically as applies on high speed (100mph and plus)lines.