Templot Club Archive 2007-2020                             

topic: 150Cant through crossovers
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posted: 1 Sep 2007 16:43

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----- from Ian Everett -----

Dear all,

I would be grateful for your collective wisdom.

I am designing a layout where the connections to the goods yard at my passing station will be from a gently-curved main line.  It will have the standard trailing connections at each end of the loop, with the connection from the down line crossing the up line via a trailing single slip.

My question is, how do I deal with the cant on this crossover/connection? I would like to cant the main lines - for appearance's sake - but I cannot see how to do this at the junction.

These thoughts have been sparked by finding a note in a 1970s Railway Magazine, which describes how such a complex arrangement had been replaced by a simple trailing point, which allowed them to remove the speed restriction on the main line.

Is it therefore, that in steam days, when track followed traditional formations, that the lines would have been laid flat and a speed restriction imposed? Would this be true of both ends of the loop - the crossover/trailing single slip at one end and the simple trailing turnout at the other?

The alternatives of either laying all the tracks at the same cant, all on the same plane. So the outer tracks are well above the inner tracks; or making the crossover go up and down over the low and high rails don't seem likely!

Or was it horses for courses, depending on the line speed and degree of cant required?

Erudition expected...

Ian

P.S. So far these plans are all in pencil on paper. I will become a real bore with questions about transferring it to Templot in the next few weeks. Apologies in advance!

posted: 1 Sep 2007 19:25

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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Hi Ian,
The alternatives of either laying all the tracks at the same cant, all on the same plane. So the outer tracks are well above the inner tracks; or making the crossover go up and down over the low and high rails don't seem likely!
There is a difference between a running line junction, where both roads are running lines, and low speed connections into a goods loop or yard. Regardless of any superelevation, such loops or yards are often at a lower level than the running lines. This uses gravity as a protection against vehicles running away, in addition to any trap/catch points.

In open country the running lines are usually individually canted, especially where tracks pass through overbridge arches or other limited clearances. Unless they are widely separated this obviously makes it difficult to have a normal crossover between them. For areas of such connections, the cant will either be reduced to flat (with a corresponding speed limit) -- this is the most likely arrangement through stations where most trains will be stopping. Or gradients will be introduced to raise the outer (or lower the inner) track, so that the superelevation is in a single plane across all tracks. This means there is likely to be an adverse cant when negotiating crossover roads, and such movements will have a severe speed restriction. There will then be a gradient down into the goods loop, which should properly be spaced at least 10ft way from the adjacent running line (15ft-2in centres).

In the case of running line junctions, special two-level chairs are combined with raked timbers to minimize the effects of adverse cant and reduce the need for speed restrictions.

There is more about all this and full chapter and verse on two-level chairs in this message:

  http://groups.yahoo.com/group/templot/message/4693

Bear in mind that there are no hard and fast rules -- different companies did things differently, no two sites are identical, and whatever you decide, someone can be relied on to produce a photograph showing the exact opposite! :)

regards,

Martin.

posted: 1 Sep 2007 22:29

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----- from Ian Everett -----

Martin Wynne said (after some very useful information):
Bear in mind that there are no hard and fast rules -- different companies did things differently, no two sites are identical, and whatever you decide, someone can be relied on to produce a photograph showing the exact opposite! :)
Useful advice at all times!

Since the connection will be just at the end of a platform, I think I'll make it flat. Yes - I am a wimp when it comes to doing difficult trackwork and the kind of switch back you suggest might sometimes be used does not appeal! I guess the flatter the track, the better the running, and I like to shunt reeeaaal sloooow.

Cue know-all comment on shunting engines' wheels spinning in reverse, throwing off sparks from the rails while fly-shunting. :>)

Many thanks, Martin,

Ian

posted: 2 Sep 2007 23:13

from:

Simon Dunkley
 
Oakham - United Kingdom

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From memory of about 15 years ago, it is worth looking at the cant change at the southern end of Salford Crescent station, on the route to Piccadilly rather than Victoria.
IIRC, trains on the old line had left hand cant into the LH curve, but the arrangement of crossovers etc between running lines and then off down towards Piccadilly became flatter as they went through the diverging routes.

I hope that makes sense: maybe someone in the area can help?

Simon Dunkley




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