Here is the question I want to put a few tunnels on my layout mid 80’s to present south east and mid alantic coal area when would start seeing concretee portals verse cut stone? I want to back date some of the areas for late steam Any help???
The Romans started using concrete in something BC!! Seriously, in northern NJ there are some Erie portals dating from the early 1900’s made of concrete. I would guess that the RR’s would use whatever material was available the cheapest for any building projects. My [2c]
You could probably get away with using either one. But to answer your question, stone was used from about the mid 1800s through the early 1900s. After that, cement casting was perfected and builders began using more and more of it because it was faster and cheaper than cut stone.
Tracklayer
While I can’t find it at the moment, one of my reference books has a photo of the front end of a N&W mallet framed in a cast concrete tunnel portal. The cast-in date is 1913.
That should meet the OP’s specifications.
Chuck (modeling Central Japan in September, 1964)
The Clinchfield RR was built 1908-1915 and used concrete portals, except for those few places where the rock was hard enough itself to not require a portal. For the “late steam” era you suggest, concrete portals would be the most common. Many of those concrete portals from 1905 or so still stand, so they can serve modern lines as well.
Bill
Here in West Virginia we still have some of the old wooden portals probably built in the 1890’s and they are still standing with trains running through. I built most of mine from pictures that I took, I’ll try to post one!
It depends on when the tunnel was built. The GN’s original Cascade Tunnel was built 1898-1900 and has concrete portals. The SP&S line between Vancouver and Pasco has concrete portals and the line was built between 1900&1908. All the portals are identical on the line as the same forms were used for each tunnel. When the cement hardend the forms were taken to the next tunnel and used again.
I hope this comes out!
It didn’t work.
Rotor
Hey
I model the Conrail Mainline in Southfork/ Johnstown Area in pennsylvania here is my portals, 
Tjsingle
Hey thanks Rotor! I got it now!
That’s some nice portal you built there!
Use the 4th link, (the bottom one) to make your pics enlarge like the one I posted from your photobucket account.
Rotor
You have to decide when your Rail Road was built. It does not matter what was being used for construction in the era of your layout because it was probably constructed much earlier than say the steam transistion era that is most common.
Dave