I believe that hitting a 5 tonne elephant might also not be good enough for the locomotive too, even though it weighs around 120 tonnes (WAP-4 or a WAP-7 considered here). That is a lot of momentum!
Anyway killing an highly sentient, intelligent and an endangered species must be avoided at all costs!
After all the Earth is not just ours, it is we who traversed into their territory, laid tracks for our benefits.....