James Robinson writes:
It makes absolutely no difference what the distribution of weight in the
train is when stopping in a hurry. The suggestion that the locomotive in
the rear is somehow a problem demonstrates a complete misunderstanding
of the physics involved.

The issue is the total mass of the train behind a derailed vehicle,
which includes the mass of the coaches as well as the power car. That
total mass is what creates the tendency to jackknife.

Er, this is why it *does* make a difference.

If a passenger car weighs P tons, and a locomotive weighs L tons
(where L P), then moving a single locomotive from the front to
the rear increases the total weight behind the Kth vehicle from the
front of the train by L-P tons; and it increases the total weight
behind the Kth passenger car by L tons.

It is one thing to decide that this difference does not pose enough
additional risk to offset the operational benefits; it is quite another
to say that it makes "absolutely no difference" and throw around words
like "complete misunderstanding" while disproving your own point.

Another issue is whether the heavier locomotive or the lighter passenger
cars would be more likely to derail in any particular situation. If one
type of vehicle is more likely to derail, putting it at the front is a
less safe choice. But I think this would depend on the particular mode
of derailment, and probably on the suspension characteristics of the
individual models; it's not obvious which is the best choice on this
basis, or, again, whether it makes enough difference to offset matters
of operational benefit.
--
Mark Brader, Toronto "As long as that blue light is on, the
computer is safe." -- Hot Millions

My text in this article is in the public domain.