A reader writes:
Can I bother you with a quick technical question? My new layout will have a tunnel and a couple of over/under areas. I'm a bit confused about how much overhead clearance I need to provide. Some articles I've read say 9", some say as much as 11-3/4". I'm modeling 40's and 50's stuff, so no tall smokestacks. I was planning on 10" from track top to the underside of bridges, tunnel portals, etc. Is that sufficient?
Thanks for getting in touch.
As you suggested, if you're only going to ever run Standard Gauge equipment (like that from AristoCraft, USA Trains, or Piko), you can get away with a fairly low entryway.
1:22.5 stuff like that from LGB and Bachmann Big Haulers is taller. Some 1:20.3 stuff is even taller.
In my case, I have and prefer running my Standard Gauge trains (mostly Aristo), but occasionally I run Narrow Gauge trains for visitors. For example, I have several Bachmann Big Hauler Christmas sets I run during the holidays.
As you suggested, I would count from the top of the rails to the bottom of the center of the portal.
My tallest locomotives are Bachmann Big Haulers with diamond smokestacks, about 7 7/8" high.
So I would put my portals at a minimum of 9" high just to give some extra room, although my Standard Gauge trains look a little low going through them. I say "would put" because I don't have the portals up on my new RR yet myself.
BUT, most of my portals are also located on curves. Depending on the length of the locomotive, the smokestack might not be dead center when it comes through. So that's another consideration. 10" is generally more than enough for me. If your portals are on straightaways and you never plan on running 1:20.3 or larger scale stuff, you may be just fine with 9" or 9.5".
Hope this helps.