This weekend we experienced another derailment with the SP&S 700 just a few yards from last years derailment with the SP4449/SP&S 700 doubleheader. We need some help from you "oldtimers" who designed and built curves in the steam days.

Both derailments were backing up entering the spiral into a 3-degree right hand curve with a total length of around 2800 feet. The curve was plotted and "best fit" obtained with a Jackson 6700S tamper with the 6.1 curve liner program. We specified one-inch of super-elevation in the body of the curve and the computer controlled the elevation to ramp in the one inch in the approximately 300 feet of the spiral. As such, the cross level difference from the rear of the tender to the pilot truck would be about three-eighths of an inch at any point in the spiral. One inch of elevation was arrived at arbitrarily assuming a maximum speed of 15 mph.

My question is: Since the tamper and computer was designed long after steam was retired, is there a difference in the way curves are laid out for present diesel-powered traffic vs in steam days? If so, Jackson needs to put a "diesel/steam" selector switch somewhere!!

We expect the Holiday Express to continue as an annual event and short of replacing all the ties with hardwood, if a geometry adjustment would solve the problem, we are game to try it.
I realize this probably bores most of you and apologize in advance for doing so.

Shortline Sammie