Scale groups of actors during runtime

I have a model train game and would like to be able to change the scale of things like the size of the track, the trains, during play while keeping the actual layout of the track the same.

There is a lot of code around distances and speeds of carriages that would be affected, so I wonder if there is a more global way of doing this where I don’t have to introduce a scale value into every speed, distance, and location calculation.