What does the white markings on top of the rail cars mean i see them on autoracks?

Question

they say excess something the train went to fast for me to see the second part what does this mean and what does it do

Answer 1

Cars with white tops indicate excess height cars, meaning they're taller than most standard rolling stock.  Boxcars of this variety are also referred to as "hi-cubes".

For the most part, this doesn't have an impact on train routing, as most (but not all) tunnels, bridges, and low clearances have been raised, removed, or rebuilt in the last few decades, as these types of cars became more commonplace.

Answer 2

It says Excess Height.  This is to let someone know, like the conductor, that should be walking his air test, that he needs to make sure the dispatchers know that is train is what we call a high train.  This automatically tell them they can run the train on certain tracks.  This is the same for example, caterpillar equipment.  I use this since I was on trains with them. We always had to notify the dispatcher that we were high and wide.  Past a certain height, you are required to notify dispatch.

Answer 3

"Excess Height" cars.    They are taller than standard freight cars and in some cases must be routed over different tracks so as to not be damaged in older, lower tunnels and bridges.

EH cars include autoracks and box cars, which were once called Hy-Cubes.