Old style hydraulic switch stand w/o electric assist. Dangerous things.
Probable Cause
The National Transportation Safety Board determines that the probable cause of the September 15, 2002, derailment of Norfolk Southern train 15T was (1) the decision by the train dispatcher and signal maintainer to allow the train to pass over the spring switch at maximum authorized speed before the switch had been adequately inspected or clamped closed and (2) the lack of company procedures requiring that train dispatchers, after receiving a report of a problem involving a main track switch, immediately stop trains or implement an appropriate speed restriction in the affected area.
http://www.ntsb.gov/investigations/fulltext/RAB0305.html
How much of a maintenance problem are spring switches?
Any part the moves is a maintenance problem - to keep it moving properly and to make sure it’s alignment is proper with the parts it moves in relation to. If MofW had their druthers, all switches and special track work would be done away with, because they are all maintenance hassles and money pits.
It CAN’T be “old-style”… I watched them install that thin just 20 years aog.
ROAR
Railroads are doing trackwork upgrades faster than they were 20 years ago!
Correct on moving parts (points or spring frog) being a problem.
The spring part wasn’t a problem here, the rod and the points were well out of adjustment … all it took was one wheel, less than round on the edges and it all goes to heck… I would have expected the switch point to be obviously smashed in the photo. The point should always be tight against the stock rail - NO gapping at all.
Spring frogs fell out of favor in the 1970’s because of the adjustment of the horn spring that closed the flangeway on the frog, especially when the rail ran (expanded in the heat and the anchors could not hold the rail in place (FRA Exceptions Deluxe). The technology has improved and spring frogs are coming back into vogue.
A big problem with spring switches (either with springs or “dashpots”) is their accident potential. If a train reverses movement after partially springing though a switch, the train will split the switch. This wasn’t so much of a problem with the short trains on interurbans, but it’s a much more serious potential with longer trains, particularly at locations where switching is performed. Illinois Railway Museum had an expensive spring switch accident with their Nebraska Zephyr trainset a few years ago(since repaired) involving this scenario.
Human Failure - pure & simple.
Very definitely human failure. It’s just that a spring switch creates more opportunity for this kind of failure, particularly if it is in an area where trains might be expected to reverse movement over the switch. Regular switches have to be aligned for a trailing movement, so the train won’t split the switch if it reverses before entirely clearing the switch. A spring switch, on the other hand, doesn’t have to be aligned for a trailing movement, since the train wil simply spring throught the points. This creates the potential that the crew will forget which way the switch was set (or won’t check it) before reversing movement. Just one more thing to go wrong. A solution to this issue that many railroads employ in yards is a switch where the points push aside for a trailing movement, like a spring switch, but then stay in the new position, rather than returning to the original position.
[quote user=“Falcon48”]
BaltACD:
Falcon48:
A big problem with spring switches (either with springs or “dashpots”) is their accident potential. If a train reverses movement after partially springing though a switch, the train will split the switch. This wasn’t so much of a problem with the short trains on interurbans, but it’s a much more serious potential with longer trains, particularly at locations where switching is performed. Illinois Railway Museum had an expensive spring switch accident with their Nebraska Zephyr trainset a few years ago(since repaired) involving this scenario.
Human Failure - pure & simple.
Very definitely human failure. It’s just that a spring switch creates more opportunity for this kind of failure, particularly if it is in an area where trains might be expected to reverse movement over the switch. Regular switches have to be aligned for a trailing movement, so the train won’t split the switch if it reverses before entirely clearing the switch. A spring switch, on the other hand, doesn’t have to be aligned for a trailing movement, since the train wil simply spring throught the points. This creates the potential that the crew will forget which way the switch was set (or won’t check it) before reversing movement. Just one more thing to go wrong. A solution to this issue that many railroads employ in yards is a switch where the points push aside for a trailing movement, like a spring switch, but then stay in the new position, rather t
Strasburg has a couple at Cherry Hill.