I recently road the TENNESSEE VALLEY RAILROAD in Chatanooga, Tennessee. It was a fun ride.
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At one point, there is a tunnel. I shot my camera out the window several times to get a look at what the tunnel liner looked like.
I was surprised by the variety of surfaces inside the tunnel. I was expecting it to be all rough rock.
Is this normal for tunnel construction?
-Kevin
Living the dream.
SeeYou190Is this normal for tunnel construction?
Depends on a LOT of things, including what the tunnel is cut through, how unstable the material is, whether there is water (which might freeze to damaging icicles), whether you want safety alcoves or similar space, whether there is material in the budget for different types of liner ... etc. The technology changed over the years, involving brick, cut stone, cast concrete, 'gunite'/shotcrete approaches, slipforms, and so forth, with cost changing over the years.
In some cases repairs will be made in some material, or replace one type of lining with another. My 'advice' would be to decide if your 'original' were made
A couple of B&O "liners" and portals, circa 1906:
Tunnel_0001 by Edmund, on Flickr\
Tunnel by Edmund, on Flickr
As Overmod states, a great deal depends on geology and geography. Some of the NYC tunnels along the Hudson River are bored through solid rock with no portal used, just bare rock.
For a fascinating look at the construction of the six "tubes" under the East and "North" (Hudson) Rivers, pick up a copy of Conquering Gotham: The Construction of Penn Station and Its Tunnels, by Jill Jonnes.
These tunnels are now at 110 years of age and "preliminary" plans are just now being discussed for their eventual replacement.
Cheers, Ed
Thank for the replies and information.
I never gave it any thought about what went into the inside of a tunnel.
Once again, my assumptions have been proven entirely wrong.
You can get a peak of the brick lining of the Howard St. tunnel in Baltimore. Don't know if the brick is original to the 1800's or a later addition. I am not planning to run camera trains so I will only be modeling what is visible from the outside of my tunnels.
Right at about 30 sec into the video
Henry
COB Potomac & Northern
Shenandoah Valley
Where I model most of the tunnels are just blasted rock so I used the painted tinfoil method and I think it looks great when you drive a camera through it.
Brent
"All of the world's problems are the result of the difference between how we think and how the world works."
During the steam age, nearly all tunnels were blasted rock. but later wood and concrete designs took over in some parts of the US.
ATSFGuy During the steam age, nearly all tunnels were blasted rock. but later wood and concrete designs took over in some parts of the US.
Not sure where you got this information.
Unstable rock Is unstable rock whether in steam or modern days, and required lining. Timber and concrete lining was common from the earliest days. Timber generally if lumber was abundant and available; concrete or stone otherwise.
Ray
Colorado RayNot sure where you got this information. Unstable rock Is unstable rock whether in steam or modern days, and required lining.
I agree.
The two B&O prints I provided above are from 1907. I think that should qualify as the "steam age". The Pennsy's Hudson and East river tunnels are cast iron with concrete lining but these are from the "electric age".
Regards, Ed
I am going to try Noch's rock paper as a tunnel liner and see if the results are acceptable.
This experiment will be on my layout test section.
Painted tin foli worked for me.
Joe Staten Island West
I use woodland scenics shaper sheets.
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I've used grocery brown paper bags. Crumple and uncrumple a few times to get some texture. Spray paints can be used to mimic the surrounding rock. Make sure the printed side that says "Kroger,Publix,Winn-Dixie etc" is not visible.
Mark B
Since it's not possible for viewers to see the interior of my layout's tunnel from the aisle, I simply used a piece of black construction paper, forming a loop over the track, and stapled it to the sides of the plywood roadbed, creating the tunnel's "walls and roof" only at the tunnel's entrances. The roadbed through the tunnel has low sides of 1/8" Masonite stapled to it in case of derailments, and is easily accessible from under the layout.
Wayne
I used 2” foam, cut slightly larger than the tunnel portals, to create the structure of the tunnel. I glued them together along the centerline of the tunnels (both are curved), and then used crumpled foil for the interiors. Painted dark grey with white dry-brushed highlights, they look good. In the centers I left off the foam and used wood and fabric to cover the sides and top (wood on one side and the top, fabric on the other side) and allow access.
The same method could be used for lined tunnels by laminating the liner material to the inside of the foam instead of the foil.
—Jeff Mutter
Erie Lackawanna’s Scranton Division, 1975
http://elscrantondivision.railfan.net