Ah yes, TTCI. Located in Pueblo, it is where they do tests of new rolling stock to measure how good the equipment is and that sort of thing. I know that they also to the occasional crash test as well as speed tests of rolling stock. I also believe they test rolling stock that was involved in an accident and see why it failed. At one point in time, TTCI actually used to be open to the public.
The area is a couple miles NE of Pueblo Co, and the connection to the E/W mainline, is to the south, and trains must pass through the huge chemical processing dump /depot site, in a very desolate, desert like area.
That'd be Bonneville Salt Flats, near Wendover Utah, northwestern corner of the state. You may have seen the movie "Worlds Fastest Indian" a time or two, which is a good movie now that i recall it.