Detail view of the support for the freeway. Note close clearance between the top of the autorack and underside of freeway. Notice also the wall on this side of the autorack that reduces the possiblity of any errant rolling stock from taking out supports for the freeway by providing a surface to slide against (compare the wall to a series of poles which could be knocked down in the direction of the track by the forward movement of the vehicle).
Concrete is NEVER one color, rather is has a base color and a series of overlays from grime, soot, stains, rust etc. as well as subtle variations in color of each pour of concrete since few structures are poured in one single shot.