Back to Back Double Junctions: Any Need For Symmetry

Discuss the prototype and how to model it.
John Fitton

Back to Back Double Junctions: Any Need For Symmetry

Postby John Fitton » Fri Nov 25, 2016 1:04 pm

My railway continues to evolve and the latest requirement is to have two double junctions on a mainline. I made a B6 right hand about 25 years ago and finally installed it a couple of years ago, although it isn't functional at this time. I need to install a left hand double junction next to it (facing the other way so to speak) and operationally it will be a lot better if it is at least a B7 or a B8 (with a switching diamond). My question is whether there is a precedent for this arrangement, or whether the prototype would install junctions of similar crossing number?

John Fitton

Phil O
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Re: Back to Back Double Junctions: Any Need For Symmetry

Postby Phil O » Sat Nov 26, 2016 9:46 pm

S & C switches and crossings are custom built to make a junction. Each junction is tailored to suit the individual location and the traffic using it, so it is not necessary for the junctions to be symetrical.

Phil.

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grovenor-2685
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Re: Back to Back Double Junctions: Any Need For Symmetry

Postby grovenor-2685 » Sat Nov 26, 2016 10:27 pm

Funny, I thought I had replied to John, with almost identical words to Phil and then a bit more.
Must have missed the 'submit' button somehow :)
The extra bit was about the diamonds, its unlikely either a B7 or B8 DJ would have a switch diamond. The diamonds on a DJ are usually of greater angles than the turnouts so would not be flatter than 1:8 in these cases.
Info on calculated DJ geometry here:
http://www.norgrove.me.uk/GWRtracknotes/R1750.PDF
and more sheets if you want curves on both routes etc.
http://www.norgrove.me.uk/permanent_way_notes.htm
Regards

John Fitton

Re: Back to Back Double Junctions: Any Need For Symmetry

Postby John Fitton » Sun Nov 27, 2016 3:17 pm

Thank you for the replies gents! I suspected as much. Sounds like a job for Martin Wynne!!

John Fitton

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grovenor-2685
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Re: Back to Back Double Junctions: Any Need For Symmetry

Postby grovenor-2685 » Sun Nov 27, 2016 3:26 pm

John Fitton wrote:Thank you for the replies gents! I suspected as much. Sounds like a job for Martin Wynne!!

John Fitton

He already did it by creating Templot ;)
Regards

John Fitton

Re: Back to Back Double Junctions: Any Need For Symmetry

Postby John Fitton » Sun Nov 27, 2016 4:39 pm

My point exactly, Keith!

Thanks for the data, very useful.

John


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