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Minimum distance of turnouts from bridges or tunnels

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Minimum distance of turnouts from bridges or tunnels
Posted by northeast_train_guy_1965 on Sunday, February 11, 2018 4:45 PM

Hello Everyone,

 

 Is there a general Proto typical rule for the minimum distance of a turbout approaching or departing a bridge and approaching or departing a tunnel portal.  I know normally there are not turbouts inside of a tunnel.  I am talking about turnouts outside of a ternal approaching or departing the portals. 

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Posted by caldreamer on Sunday, February 11, 2018 4:52 PM

I remember seeing an MR picture in "There is prototype for everthing" of a turnout right in the middle of a PRR bridge in Philadelpha.  If the railroad needs to put a turnout somwhere they do it.  Anything goes in railroading to get the job done.  I am sure some railroad has done what you are asking.  Anyone know of specific instances?

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Posted by cuyama on Sunday, February 11, 2018 5:13 PM

Generally the prototype keeps some space between turnouts and bridges and tunnels (for safety in case of derailment). Yes, there are exceptions in real life -- but they are well-known because they are exceptions.

For the model, the most important thing is making sure that you have access for cleaning and maintenance, and room for switch motors as necessary. For those reasons, I generally avoid turnouts on bridges and in tunnels. For example, in my Harpers Ferry track plan published in Model Railroad Planning 2017, I put the branch line turnout on the staging deck rather than within the tunnel (which is one of those well-known rare prototypical exceptions).

Byron

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Posted by NHTX on Sunday, February 11, 2018 5:21 PM

     In agreement with Caldreamer, a railroad will place a turnout wherever it needs one BUT, there are some things to consider.  It is doubtful a turnout leading directly into a switching situation would be placed at the mouth of a tunnel of any length.  In a mainline situation where the passage of the movement was continuous, it would be OK to have a switch right at the mouth of a tunnel.  Having the track used as a switching lead would lead to asphyxiation of the crew in the back and forth, pause while waiting for the next move, switching operation.

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Posted by ROBERT PETRICK on Sunday, February 11, 2018 5:59 PM

I would treat the turnout as any other fairly sharp curve and allow one full car length before the portal  (bridge or tunnel), if possible. That works out to about 6" in N scale or 12" in HO. Helps with side scraping clearance and helps with aesthetics.

My opinion, of course, but that's what I would do.

Robert

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Posted by j. c. on Sunday, February 11, 2018 6:15 PM

my thoughts on this are the railroads did what they had to  to get the job done , so if you want to need  turnout on bridge or at a tunnel entrance do so without thinking about it . can't post on this site but as example there was a swing bridge in kansas with a turn out on it . numerous turnouts on fixed bridges . also there are turnouts starting at tunnel mouth , but don't have any photos of a turnout in a tunnel . think that would be inviting trouble. 

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Posted by gregc on Sunday, February 11, 2018 6:47 PM

greg - Philadelphia & Reading / Reading

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Posted by NWP SWP on Sunday, February 11, 2018 6:54 PM

The SP had miles of track, including switches, crossovers, and even a turn table under the miles of wooden snow sheds that once topped Donner Pass...

Steven

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Posted by peahrens on Sunday, February 11, 2018 7:15 PM

While your question is on the prototype, I can comment on my modelling angle.  I wanted a turnout at a tunnel entry so I could have a passing siding start there.  Understanding the practical issue of more possible derailments going into the tunnel and the maintenance angle I made a compromise.  I ensured I got the throwbar outside the tunnel, and I tested extensively for reliability of my trackwork skills there before proceeding to add the tunnel portal and adjacent hills / rock work construction.  

  IMG_7822 (2) by Paul Ahrens, on Flickr

 IMG_7826 (2) by Paul Ahrens, on Flickr

 

Paul

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Posted by NHTX on Sunday, February 11, 2018 9:33 PM

     Mr Ahrens, you have done some fine modeling but my question is from a prototypical point of view, not a criticism.  Not knowing the length of your tunnel or passing siding, how does a train intending to exit the bore onto the single track in the picture avoid gassing the crew, if due to a meet, they must wait on this siding?  If the tunnel is short enough, and the siding is long enough, they may hold short of the tunnel --but that would negate the need to have the siding extend into the tunnel.

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Posted by Enzoamps on Monday, February 12, 2018 2:43 AM

The famous Harpers Ferry, West Virginia CSX mainline (former B&O) westbound exits the 900 pluss foot tunnel at the river on Maryland side right into a turnout.  The main line continues across to the station and on to CUmberland, the branch also crosses the river and near the W VA end there is a turnout within the bridge.

 http://www.railfanguides.us/wv/hferry/harpersferry1.jpg

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Posted by richhotrain on Monday, February 12, 2018 5:43 AM

I say, put it where you want it. 

Rich

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Posted by SouthPenn on Monday, February 12, 2018 9:30 AM

Switch on a bridge.

South Penn
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Posted by ROBERT PETRICK on Monday, February 12, 2018 9:45 AM

SouthPenn

Switch on a bridge.

 

Nice photo.

That doesn't seem so severe in the 1:1 world, but could be problematic in a 1:87 (and especially a 1:160) environment. Hard to get fingers between girders to throw the bar, and nowhere to hide the Tortoise underneath.

But good research, and good photo. And, there appear to be two switches (crossover). And a wye to boot. And what's that little building at the middle of the straight part of the wye?

Robert

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Posted by cuyama on Monday, February 12, 2018 10:49 AM

ROBERT PETRICK
That doesn't seem so severe in the 1:1 world, but could be problematic in a 1:87 (and especially a 1:160) environment.

+1

This is the point.

Yes, there are exceptional situations in real life. But when building a layout, one needs to allow for construction, adjustment, cleaning, and replacement. Imagine giant hands trying to reach into some of those scenes to fix something.

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Posted by selector on Monday, February 12, 2018 11:52 AM

Looks and fun-factor are two things that really count, but they can have their values seriously eroded by their complexity when things go wrong.  As these two gentlemen wisely advise, what you can't reach or see easily is where your attention is soon enough spent on our layouts. It's where we soon run into serious problems that really detract from the intended fun. Alas, I had to learn that horrid lesson on my third layout.  Yes, I was a bit smug and thought I had it all figured out...but I got spanked.  I had a turnout, a Peco #6, buried in the back of my large helix.  I was smart enough to make it accessible, but I had to slide under it on my back.  How many times do you think I was on my back under dat 'ting? At least 20.

Back to the real world of railroading....making double-wide trackage in a tunnel greatly increases the cost of creating the tunnel, including placing a turnout to a parallel track inside a tunnel.  So, if it could be done, a tunnel was kept to single tracks to the extent practicable.

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Posted by SouthPenn on Tuesday, February 13, 2018 8:51 AM

SouthPenn

Switch on a bridge.

 

I believe the small building is the switch tower.

South Penn
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Posted by riogrande5761 on Tuesday, February 13, 2018 9:25 AM

northeast_train_guy_1965

Hello Everyone,

I know normally there are not turbouts inside of a tunnel. 

I'm not sure that is true.  The D&RGW laid the turnout so that it was at least half inside the east portal of Moffat tunnel to protect the points and mechanism from ice and snow buildup.  The Moffat tunnel was the 6.2 mile tunnel at the continental divide on the D&RGW mainline in the Rocky Mountains.  Other RR's may have had the same practice.

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Posted by NittanyLion on Tuesday, February 13, 2018 11:26 AM

riogrande5761

 

 
northeast_train_guy_1965

Hello Everyone,

I know normally there are not turbouts inside of a tunnel. 

 

I'm not sure that is true.  The D&RGW laid the turnout so that it was at least half inside the east portal of Moffat tunnel to protect the points and mechanism from ice and snow buildup.  The Moffat tunnel was the 6.2 mile tunnel at the continental divide on the D&RGW mainline in the Rocky Mountains.  Other RR's may have had the same practice.

 

Also, New York Penn Station, Baltimore Penn Station, and any number of other major stations have no qualms about all the underground, enclosed turnouts they want. 

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Posted by GraniteRailroader on Tuesday, February 13, 2018 11:35 PM

gregc

 

 

Greg, where was this taken? It looks awfully familiar from my childhood, but the gauntlet track across the bridge doesn't make sense from what I can remember.

It would have created a double diamond just behind where the photog. is standing, and I don't ever remember that.

 

 

EDIT: Just went back and checked Google Maps to look at the white buildings in the background. This absolutely has to be looking at the GMRC in Bellows Falls, Vermont, with the connection to the (now NECR) CV going to the left, the GMRC main running in the center, but I cannot identify the track going to the right of the photo/photographer.

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Posted by BMMECNYC on Wednesday, February 14, 2018 8:46 PM

Five on this somewhat famous bridge.  https://www.google.com/maps/@40.3322217,-76.9148936,141m/data=!3m1!1e3

Extension rods can be made from .061 wire and switch motors mounted completely under the layout.  Or the remote mounting kit could posibly be used. Or you could put servo motors in the stonework.

A few near here, both in OH and KY. 

https://www.google.com/maps/@39.1027806,-84.5397831,146m/data=!3m1!1e3

One here, New Albany

https://www.google.com/maps/@38.2847729,-85.8021761,129a,35y,45t/data=!3m1!1e3

More examples near Pittsburg, Pa

https://www.google.com/maps/@40.3871056,-79.8527837,242m/data=!3m1!1e3

This one is actually inside the portal: McKeesport, PA

https://www.google.com/maps/@40.3527479,-79.8706336,213a,35y,180h,44.96t/data=!3m1!1e3

 

Rule 108: In case of doubt or uncertainty, the safe course must be taken.

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Posted by wjstix on Thursday, February 15, 2018 8:21 AM

caldreamer

I remember seeing an MR picture in "There is prototype for everthing" of a turnout right in the middle of a PRR bridge in Philadelpha.  If the railroad needs to put a turnout somwhere they do it.  Anything goes in railroading to get the job done.  I am sure some railroad has done what you are asking.  Anyone know of specific instances?

 
I've never seen any specific guidelines for the prototype railroads. As someone noted, a turnout is a likely place for a derailment, so a railroad if possible would want to allow enough room (if possible) that a derailment didn't involve the tunnel or bridge. I would say on a model railroad, where say two tracks come together to go over a bridge or through a tunnel, I'd leave about one car length (40-60') clear.
 
BTW note that in the photo earlier of two tracks coming together to cross a small bridge, it's actually a 'gantlet' - the two lines aren't coming together with turnouts.
Stix
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Posted by mbinsewi on Thursday, February 15, 2018 10:16 AM

wjstix
BTW note that in the photo earlier of two tracks coming together to cross a small bridge, it's actually a 'gantlet' - the two lines aren't coming together with turnouts.

I'd like to find out where this is.  The gantlet is what first caught my eye, but I think Gregc was pointing out the turn out, just before the bridge, on the left.

I checked out the Bellows Falls thing, looks close, but I don't see the gantlet.

Mike.

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Posted by GraniteRailroader on Thursday, February 15, 2018 5:28 PM

The guantlet has been removed.

I've got an email in to one of my previous co-workers who has been employed by GMRC/VTR/VRS as long as I've been alive asking about it.

I have confirmed though, that the photo is actually on the Green Mountain, with the diamond at the photographers back, facing North/Northwest...

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Posted by GraniteRailroader on Friday, February 16, 2018 1:55 PM

Got this back at lunch, from my previous coworker...

 
 
The photo you sent was taken sometime before 1985 because that was about the time the silver Western Union shack on the other side of the canal was moved to North Walpole. 
 
What you don't realize is that there were once several switches within this view.  What you see remaining are from left to right:
1. The old "B&M Middle" which once ran across the street to the freight house and reconnected to the B&M Main.
2. The actual connection to the B&M Main.
3. The GMRC Main that actually connects to what is the Straight Track east of the diamond.
 
However, you can also see switch ties in front and to the right.  Between 1 & 2 you also had the real Rutland Main line and the extra track between it and the Straight that was used for baggage and express transfers.  Then to the far right there was a track called the North Boston which was the actual yard lead for freight departures.  Add those together and you get six track emanating from the canal bridge to the B&M and four diamonds.

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Posted by gregc on Friday, February 16, 2018 7:36 PM

GraniteRailroader
Greg, where was this taken? It looks awfully familiar from my childhood, but the gauntlet track across the bridge doesn't make sense from what I can remember.

sorry, don't know.  Probably found the photo searching for gaunlet.

greg - Philadelphia & Reading / Reading

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