Does anyone know when superelevating curves bacame a standard practice? Was it only done for high speed mainlines on Class I Railroads or did it filter down to branchlines as well?
I’m modeling a small regional line circa 1910 and am pondering whether “to tilt… or not to tilt”.
I don’t know when superelevation was first used but the practice was probably well established by your time period.
The amount of superelevation depended on the sharpness of curve and the speed of trains run on the line.
Some typical prototype numbers (AREA recomendations from that period):
3 degree curve, radius 1910ft ( HO scale 263in) 20mph 3/4in, 30mph 1-3/4in, 40mph 3-1/8in 50mph 4-7/8in, 60mph 7-1/8in, 70mph 9-1/4in.
10 degree curve, radius 574ft (HO scale 43in) 20mph 2-5/8in, 30mph 5-7/8in
With the correct combination of curve, speed and superelevation, the prototype train leans into the curve and tracks better. Too much superelevation may cause slower trains to tip over toward the center of the curve (this is a problem to be aware of on model trains too).
Superelevation had two purposes as I understand it. One was to allow passsenger trains to traverse mainline curves at a higher speed more conducive to passeneger comfort. The second reason was to help guide freight cars through a curve to reduce wheel wear and reduce spreading of the rails. Wheel treads are tapered and do not have a differential like an automobile so when going around a curve the outer wheel rides clsoer to the flange (bigger diameter) then the inner wheel. I used to ride the Reading Fox Chase line into Philadelphia with my Dad and the RDC would stop at Olney on a superelevated curve. I always wondered why the car didn’t fall over because it was very difficult to stay in your seat with the train stopped.
South of Reading PA on the former Reading mainline is the Klapperthal curve which was some of the first rail designed for steam engines exclusively (instead use with horse drawn wagons). There are mid 19th century photos showing the track as being superelevated. Moncure Robinson of VA was it’s chief surveyor and civil engineer.
Of course the Pennsy’s famous horseshoe curve was superelvated from the start and that was completed in 1854 - 150 yrs ago! Civil engineers must have figured out how to cant the tracks early-on to keep the trains rolling as fast as possible.
Similar to ndbprr’s experience is the Narberth Station on the ex-Pennsy Paoli local west of Philly; That station stop is on a superelelvated curve too; makes boarding and deboarding a real adventure.
Mark