Crossovers railroad practice

[Valeriy]

I am building Northern Pacific 1930-1940 station layout.

I found 1918 NP Maintenance Rules.

Link: http://research.nprha.org/1918%20NP%20Maintenance%20Rules/Forms/AllItems.aspx

Page 52 has crossovers between parallel tracks rules. This crossovers has identical frogs numbers (7-7; 9-9; 11-11).

My question. Is it possible in real railroad practice ( Northern Pacific Railway 1900-1940) to combine in one crossover different frog numbers (such as 11-9)?

 

Sincerely,

Valeriy Ukolov.

[dehusman]

Its physically possible to do but there will be a kink in the track and a bad alignment which is why the rules say not to.  If they did it it would probably be an emergency situation because it would be a derailment risk.

One can force fit a lot of things.

[tomikawaTT]

That might happen if the crossover was at the entrance to a curve.

However, that kind of alignment would only happen if forced on the locating engineer by some non-negotiable situation.  Ordinarily it would be avoided - possibly by moving the crossover a few (hundred) feet to a more suitable alignment.  Unlike model railroaders, prototype tracklayers were seldom bound by, "It has to go HERE!" conditions.

I'm currently designing a puzzle palace of multiple slip switches connecting parallel tangent tracks. The acute angle frogs will all be #5 - all fourteen of them.  [edit:  The two crossing frogs will have a different number, 1/2 that of the others.]

Chuck (Modeling Central Japan in September, 1964 - with hand-laid puzzle palace specialwork)

[wjstix]

There probably would be a way to make it work, but it would be difficult on the model (and in the real world); it would make sense for the two switches to "mirror" each other.

Also, railroads set the frog angle based in many cases on the speed trains were expected to go through the turnout. I don't know the exact numbers offhand (you can find them online and in books) but let's say you need a No.14 turnout or greater to go through it at 50 MPH. If you have a double track mainline where the speed limit is 50 MPH, using No. 14s for the crossover is going to allow you to cross over at the track's speed limit.

If one turnout is No. 14 and the other No.12, you're going to have to slow down to the speed limit for a No. 12 turnout. If you can't do two No. 14s for some reason, and had to have a No. 12, you'd probably do two No. 12s and put in a speed restriction when using the crossover.

[Valeriy]

Thanks all for interesting answer.

It is my mistake. I did not noted the link of my station image and description of the station working.

This is the link of my project station image - http://smages.com/?v=statioaka.jpg (please click on this image to see the large size).

Is it correct plan for virtual NP station 1930-1940?

There is only one mainline – I (noted by red color). Passenger & freight trains pass without stopping on mainline I. Passenger trains may stop on the track 2 (and on mainline I if it is need). Freight trains may stop on tracks 3 & 4.

So, I marked (by red color) turnouts with frogs #10 (2,4,19,17,1) All other turnouts has frogs #8.

Is it correct to plan turnouts # 15 & 3 with frogs #8 (or it is better to plan turnouts #15 & 3  with frogs #10)?  I would like to build realistic NP station period 1930 – 1940.

 

Note. In Russian railroad practice it is possible to install crossovers with different frogs (22-11; 11-9; 9-7).

 

Sincerely,

Valeriy.

[Steven S]

Valeriy

My question. Is it possible in real railroad practice ( Northern Pacific Railway 1900-1940) to combine in one crossover different frog numbers (such as 11-9)?

 

Did you take geometry in school?  You should have learned about two parallel lines intersected by a transveral, and how opposite angles are equal to each other.   Therefore you need equal frog angles.

http://www.math10.com/en/geometry/angles/angles.html

 

Steve S

[mactier_hogger]

Just to throw some light on our hopelessly tight model turnouts.....in the real world, the speed limit through a turnout is double the frog angle. So a number 14 turnout would have a speed limit of 30 mph ( rounded up from 28). Our # 6's therefore are really only yard switches limited to 10 mph! Such are our compromises!

[Anonymous]

the bottom line is if works 4 u then it is all good. in the real world of trains there are standards but in the old days if it work and ain't broke then there is no need to fix it!!