Train handling... There was probably a grade there or the locomotive engineer was was power braking through the curve... envision the train as a rope you are pulling around a curve... The more tension on the rope the more lateral force to the inside it will have
In that picture, the wheels may have dropped inside the gage (wide gage)...and then the drawbar pull “stringlined” the train.
Great explanation! Didn’t even occur to me,then again I’m no train man!