I would like to put a tunnel on a 2% grade. It will be 2’ to 3’ long and both ends will be visible from the main viewing area. I am wondering how it will be from an appearance point of view. I don’t want it to look like it’s just a bad modeling job where I forgot to use a level. In the real world it would be unlikely you could see both ends at the same time. Have you done this ? If so how does it look? Could you post photos? Thanks
Brent
The majority of tunnels are on grades, just as bridges are on grades. They may be on a slope like 1/200, or on grades nearer to 5%, depending on the engineering problems and the needs and economics of the host road.
If you do this, do it without guilt…unless you forget to provide access in case you have any boo-boos and can’t reach in from either end.
-Crandell
A lot of ‘real’ railroad tunnels ar on grades! My layout has a 17’ tunnel that is on a 2.7% grade’ As long as the construction is solid, it should be no problem(you should has some kind of access in case you do have a derailment).
Jim
Brent:
Fear not, my friend [:P], every tunnel on my trans-Sierra Yuba River Sub --and there are five of them, are not only on 2% grades, but on either 34 or 36" radius curves. Don’t have a straight-track tunnel in the bunch (at least I don’t think so).
Out here in the West, tunnels and grades go together like hand in glove. So drill away! [^]
Tom [:D]
As for seeing both ends of the tunnel at the same time. Is there a chance of using a view block? It could just be a straight piece perpendicular to the track, just sky with maybe a cloud or two.
Just a thought.
Good luck,
When putting tunnels on a grade, are the protals supposed to be perpendicular to the track or straight up and down?
When I first read your question, I thought “there’s no difference between perpendicular and straight up and down.” Then I thought about a track that isn’t level from side to side, as in super-elevated track.
So, the answer is - maybe! If the track is level side-to-side, the portals would be both straight up and down and perpendicular to the track. Where the track is NOT level side-to-side, the portal can be tilted to provide clearance, however, I don’t think you’ll like the looks of it and it probably isn’t prototypical.
Real tunnel portals are built vertical and level. This construction method insures that the portal is stable and properly supports the weight placed on it. Tracks running through the tunnel may or may not be level, but the portal should be. The portal may need to be made larger or taller if the tracks are curved or elevated on one side to provide the clearance needed for the trains.
Hope this helps.
Darrell, quiet…for now
In the real world they would be vertical most of the time. Possibly leaning in but not out. Remember Fudd’s first law of opposition: If you push something hard enough … it will fall over. The hill pushes on the portal.
I’d forgotten about tilting track, but my question did get answered by the 3rd paragraph. So it’s leve, and straight up and down for the portal, not at a 90 degree angle to the track.
You might find them either way there, Dude, but I would venture that you are more likely to find a concrete portal standing straight up and down.
Now there’s the rub, and the reason I posed this question. The photo I have of a pretty decent looking layout has the portals perpendicular to the track that is on a grade, and thus they look like they are leaning. All in all it looks baaaaad. I think if the portals in the photo were straightened up it would look sharp! I was worried that if you could see the track entering and exiting the tunnel on a slope it would look cockeyed. But not if everything else is as straight as it should be. Thanks a bundle.
Brent
If in doubt, look at the prototype - specifically the joint UP-BNSF Tehachapi route.
There’s one place between the Loop and Tehachapi where you can see all four portals of two short tunnels. It’s a mighty short train that doesn’t have locomotives in daylight at one end, cars in daylight in the middle and the rear-end device in daylight at the end.
Masonry (stone and/or concrete) portals are usually vertical. So are telephone poles, buildings and bridge towers/abutments. Roof and floor lines are on true horizontal. Only the roadbed itself is at some non-level line.
If a tunnel covers a superelevated curve, the designers allow for the greater width and height required for top-of-the-boxes and middle-of-the-cars clearances. The most extreme example with which I am walking-through familiar are the tunnels on the former Hoover Dam access route, now the “Railroad Tunnel Trail,” adjacent to Lake Mead. The tunnels had to clear huge steel penstock sections riding down to the dam on flat cars. They were only single track, but could easily have accepted two tracks with room to spare.
My own prototype is notable for a rapid succession of short bridges and short tunnels on a twisting, squirming grade. I’m looking forward to modeling that.
Chuck (Modeling Central Japan in September, 1964)
Thats how I get from one level to the next on the new layout. Go in the tunnel and go around a semi helix as I like to call them and come out on the next level. I don’t have the room just yet to do it on more of a straight run. I picked this trick up when visiting a large home layout. Obviously if you put the tunnel portal Straight up and down as you call it and the roadbed is at a 2% grade it will cut down on the over head clearance. If your not happy with the way it looks if you keep it with the grade you always have the option to skew it a little by either placing wedges under the tunnel portal of cutting thethe bottom surface of the tunnel portal at a slight angel, I would opt for the small shim myself. Just enough so it looks like it’s cut into the mountain at an angel which appears to the eye to be up and down but really isn’t.
In the end it’s all about what yo perceive to look real and good.
Classic in your backyard (well, not quite but close enough!) is CP’s spiral tunnels. On grade, with both ends visible at the same time.
You want a tough tunnel call? How about the Othello (Quintette) tunnels on the old KVR. They are now a provincial park, just outside Hope. Nice walk to look at the amazing engineering on those!
Everything so far is great advice. My comment is to be careful that your tunnel doesn’t look like a hole punched through a loaf of bread. The geology should justify a tunnel rather than a much less expensive “cut.” I won’t say that the “Loaf of Bread” thing never happens in prototype railroads (there’s one here in Utah), but they are rare. Usually a tunnel is used when the obstructing mountain is so big that boring a hole makes more sense than cutting a man-made pass through it, or the obstruction is really a giant rock and blasting a hole is a reasonable thing to do.
In the case of the former (big mountain), there are usually cuts as the track approaches the tunnel openings; these help us modelers hide the entrances - so only one is visible at a time. It also helps that the mountain is so big that it blocks the view of one or the other tunnel opening.
Just a couple of things to keep in mind. Post pictures of your progress. Good luck.
I remember when I got back into MRR I wanted to do the spiral tunnels. It would take just a little to much real estate if I wanted to do it justice though. I have the Othello tunnels on my hit list though.
Brent
Most prototype tunnels are rather short. Trains are typically much longer than tunnels. For instance, of the two closest railroad tunnels to me, one is just long enough to burrow through a ridge the width of a six-lane freeway, and then after the railroad track crosses a canyon on a steel viaduct bridge, there is a very short tunnel piercing a narrow spur of a hill (maybe Easterners would redefine our hills as mountains).
Mark
I would encourage you to look at pics of examples of tunnel portals for your RR in yourchosen area and period.
Due to the fact that each tunnel is pretty much unique tunnel portals are also pretty much unique. Okay, there are basic designs but they get adjusted to the local situation which is a combination of topography and geology… and which direction the RR is heading through it… in 3 dimensions (plus time).
A portal in hard rock is very different from a portal in shale, sand or sloppy mud… and its design varied with time and resources…
Don’t forget that the conditions at one end of a tunnel may be different from those at the other end. This can apply to a short tunnel - if the strata slope away bottom to top at both ends of a tunnel they will lean into the tunnelat one end and away from it at opposite end. OR the material may change - rock at one end may be solid but shattered at the one end may be clay and the other sand…
No one seems to have mentioned that portals can be stepped (rather than sloped) in various ways - the face may not be straight up in a single rise… it may also be deeper one side of the track than the other… among other variations… the land may slope across the portal… and the slope may not be at a right angle tothe track…
The thing to do is to figure out what you are tunnelling through and then design a portal that will do the job.
Don’t forget that portals were made of any materials from wood through stone and masonry to poured concrete. Can’t say that I’ve seen a steel portal yet… [:-,]
There may also be a question of sloped cuts, retaining walls or cribbing on the approach to the portal… these are whole subjects in themselves.
The essential thing for a modeller to bear in mind is that if the track is not
Take a look at tomustang’s post here. As someone said, there’s a prototype for everything. [:)]
http://www.the-gauge.net/forum/viewtopic.php?f=35&t=2192&start=15
-Crandell
Hey! [:D] WOW! [(-D]