Tunnel Portal Options

I would use an appropriately sized piece of 3/4' foam board insulation commonly available at one of the big box stores in either pink (HD) or green (Lowes). It can be cut to size; scored to make it look like blocks or stone; painted and weathered. Check to see if the store has any scrap pieces around.

It looks like you may have to cut into the existing mountain, but that should not be an issue.

Carve your own from foam. See the thread below.

https://ogrforum.com/...4#182466532415443784

I made this with foam core - and a few sticks (smaller width than popsicle sticks)..  Just as @Richie C. said, the foam core can be scored.

walt

Thank you gentlemen, your responses have given me direction.

Jay

Jay, as mentioned above, making a "custom" opening from a foam product is a great option.  You can see my finished product to the far right in the picture. I had a similiar issue to yours with the 20" passenger cars coming out of the tunnel on the curve.

I had to think a while about how to finish off the portal to make the end product look somewhat realistic.  Under my exterior deck was a ton of small rocks put there by the builder to help drainage under the deck.  Those rocks were my solution.  I used a dab of construction adhesive on each rock to adhere the rocks to the foam.  I'm satisficed with the finished product...

Photo shows the East Portal of a tunnel on my 10'-by-5' layout with O-54 curved track. The portal is soft urethane (stone colored - although mine is painted) and easily carved. It is 9-inches wide by 8-inches high. The opening is 5-inches wide by 5-1/2- inches high. It is available from one of the major online scenery suppliers and is large enough for you to enlarge the opening to the 7-inch width and 6-inch height (rectangular) that you require. Also notice the stone wall on the right side of the tunnel interior. It is also urethane embossed with colored stone blocks. It comes in sheets about 14-inches long by 7-inches high by 5/8-inch thick. You could buy two such pieces and cut and glue them (with yellow carpenter's glue) to make a portal. You could also buy two of the urethane portals and cut and glue them to make a single portal with the larger curved opening that you require. In my opinion, the advantage of using pre-embossed urethane instead of carving from foam insulation is that the stones look realistic, are pre-colored, and are a good base for paint. Are you sure that you need a 7-inch by 6-inch opening or could it be smaller? My 18-inch MTH Premier Madison passenger cars easily pass through this opening with an O-54 curve. Your O-42 curve will require a larger opening but I'm not sure of exact dimensions.

From your picture, it's not evident to me that you really need an opening with 7-inch width. I think it could be smaller - even with an O-42 curve. The portal in my picture is just wide enough for Atlas O 21-inch Horizon coach cars to slip through with 1/8-inch clearance on an O-54 curve. Cut a cardboard template and experiment with different openings to see what you really need.

MELGAR

Melgar - That's awesome.  Are you saying you carved that out of a flat sheet, and put that design and the texture of the stones on it.  That's really well done, like a piece of art.  I like it!

I have used the ready made portals like Mel did, on our club layout. They are easily cut to add pieces and make a larger portal. Portals are from Scenic Express. I have also made molds of the same and made plaster portals.

I cut up a store bought polyurethane portal also, then changed the layout all around.  I’ll see if I can use it again or buy another and start over.

@William 1 posted:

Melgar - That's awesome.  Are you saying you carved that out of a flat sheet, and put that design and the texture of the stones on it. That's really well done, like a piece of art.  I like it!

@William 1,

William,

No. The portal and interior stone walls come embossed (pre-carved) with the stones and painted stone gray. They are urethane - soft and easy to cut. If you buy two portals, the first one can be cut down the middle and a piece cut from the center of the second one can be inserted to make the opening wider. Then, two more pieces can be cut from the second portal and added to the bottom of the first one to make the opening higher. This material can be glued together with yellow carpenter's glue and painted after being assembled. Cutting necessary but no carving of the stones.

More views of portals, tunnel and hill below.

Scenic Express also sells double-width portals that seem to have large-enough openings for @Tranquil Hollow RR.

MELGAR

It is also possible to carve a reasonable facsimile of the Lionel postwar portal, if you are into that:

Details here:

https://ogrforum.com/...16#12974798585284616

While I agree that high-density foam is the better base, you can even  use the cheap white stuff, salvaged from shipping containers, etc. To create portals for a drop-over tunnel for my brother-in-law's seasonal layout, I used some salvaged white foam pieces to both create the tunnel structure, as well as emulate the commercial portals I had previously used on my layout:

After creating the portal 'blanks' out of styrofoam, I carved the stone outlines with a hot wire tool, then painted the 'stones' in differing shades of gray and brown, then finished with some black dry brushing to simulate the effects of years of coal smoke. Not too bad for free!

Thank you Paul, Melgar, William 1, Don, Mark, Pete, and Steve. Your insights are greatly appreciated. I knew I would get the guidance I needed.

Jay

You could certainly carve an opening of desired dimensions out of foam board as suggested, but there are several Pennsy tunnel portals with varying opening widths that can be modified to suit your specific needs. Local train shops commonly carry them, or you can order from Scenic Express: https://www.sceneryexpress.com...stems/products/1076/.  Saves landscaping the final product.

I attached photos of 2 portals on my layout to show different modifications of the Pennsy portals. Enjoy!

Michael

Thank you Michael, your portals look great. I really like the interior support columns; that’s different and realistic. I have a scenic express portal but it is just the angle and the adjoining track geometry that causes the problem. Plus, my 18” mu’s need to fit. I’m leaning towards making something from foam board. Thank you for your advice.

Jay

I used foam for almost all my portals. It gave me the flexibility to span the tracks anyway that was needed.

Of course, there is always balsa wood:

Steve and Pete, thank you for the photos. The balsa wood is very unique and perfectly done. The foam portals also look outstanding. These excellent ideas are greatly appreciated.
Jay