3: AAR plate F clearances for interchange, from the Official
Railway Equipment Register.
rail. Unfortunately, the same standard allows a maximum width
of 8' 6 3/8” at maximum height. Our freight car was rolling
through a curve, increasing the car's overhang on the inside of
the curve. AAR standard S-2041-94 sets the maximum width
of cars with various track centers. So a long car with its truck
centers spaced at 80' can be only 8' 3” wide to meet clearances
because so much of it will overhang the inside of a curve. That
NMRA gauge allowed only 8' of width at maximum height.
Bang, scrape, and maybe a car derailed. We are still within
clearances, so what happened?
We're not done. The AAR maximum widths are based on a
curve radius of 441' 8 3/4”. That's about 60” when scaled
3
