Hey Everyone;
Trying to put my first bridge up, Speaking prototype on any bridge, any engine, any railroad, what is the basic height requirement between the top of the highest car and the bottom of any bridge??? Or does it go from rails to bottom of bridge?
Thanks in advance for your assistance!
Hi
You didn’t mention what scale you are modeling in, but it is measured from the top of the rails.
NMRA in HO scale is 3 inches minimum clearance.
N Scale is 1 21/32" minimum clearance.
You should purchase an NMRA guage, it will assist you with clearances, and many other things.
On the prototype, it varies. Some lines can handle anything, while others are not cleared for double stack container trains or autoracks. The NS “Rathole” line was recently upgraded to handle autoracks and double-stack containers by boring into the tunnel ceilings. Even with the increased clearances, there’s only about a foot or less between the top of the container and the tunnel ceiling.
But on a model, you want to go with 3 inches for HO and 1 21/32 for N scale, as mentioned above.
Good luck!
You need to get an NMRA clearance gauge. That’ll clear up a lot of fog for you.[;)] BILL
The AAR specifies a 22 foot clearance from the top-or-rail to the bottom-of-structure–or to the roof of a tunnel. This measurement dates back to the days when railroad cars had roofwalks and were not as tall as today and this left enough clearance to allow a 6 foot tall man on top of a car to pass under a bridge without bonking his head. Telltales were required where that 22 foot clearance was not met. You don’t have to worry about telltales today because train crew ain’t supposed to be on top of (moving) cars in the first place.
Today it is the railroads responsibility to insure that tall cars–autoracks or doublestacks–have enough clearance to pass safely under bridges or through tunnels.
Sure it was the Rathole that was recently upgraded and not the Pokey? I’ve got both of the Pentrex videos from the mid-1990s on the Rathole, and I seem to remember double stacks in both videos.
Kevin
3" would be the minimum, but would be OK unless you’re running very high equipment…I think I just read in a review of Athearn’s stack cars that with containers they’re right about 3" high. If you can do it, having more clearance will look more realistic.
Thank you Geared Steam, some valuable information I needed.
Thank you TrainmanTY, Reklein, R.T. Poteet, Chatanuga & Wistix, appreciate all of your information. I definately need a gauge. Lets get back to building! Railroadinmedic in NC.
You are welcome !