Brought to you by the makers of replacement plastic truck frames for locomotives on DCC layouts!
FWIW the placement of a derail, by CSX and NS specs, is to protect an industrial siding or yard track, with parked cars, from being pushed or allowed to drift onto a main line. And the requirement is that that have to be at least 50' back from the fouling point.
There are two types of derails, these kind of 'flopover' derails, and split-point derails like half of a switch that goes nowhere. The flopover derails have a significant fault that they are only as good as the ties they are spiked to. We've investigated several derailments where the car hit the derail, knocked it off the (rotted) ties, and just kept going....to derail on something else. One particularly bad accident allowed standing covered hopper cars to roll a couple miles downhill into a parked and empty excursion train, lots of damage, derail was set but knocked free.
