Is the relationship between rail track gauge and lateral stability, linear?
If the gauge of the rails is increased the height of the locomotive and carriages likely will also increase. As the train rounds a turn there is a couple (opposed forces tending to cause rotation) represented by the mass of the locomotive concentrated at its center of gravity acting outward and a counter force provided by the outside rail restraining the outward motion. The speed of the locomotive, sharpness of the curve, slope of the curve and height of the center of gravity above the rails all play a part in a rather complex situation that may not always be linear. The rails are set on wooden sleepers (ties) that have a little give rather than in concrete, likely to reduce impulse (similar to dropping a glass on a carpet rather than on a concrete floor!).
