I had an opportunity to visit Kansas City this past weekend and spent some time exploring the Hill Track in person with some model railroad friends. I'm still working on getting through the pictures and will post the more interesting ones here soon.
The most notable detail learned from the trip was the elevation changes that the line experienced. While some of that information can be gleaned from topographic maps, nothing beats the in-person experience and GPS readings (thanks Keith & Mark!).
At just over a mile in total length and with a total elevation change of 100 ft, the average grade works out to be 2.2%, which is towards the steeper end of the spectrum for railroad grades. Of course, this is a small industrial spur but the laws of physics still apply. Most spurs from the main track were level, so that adds to the visual interest of the scenes.
The one thing I regretted not doing while there -- I only thought of it while on the plane back home -- was to measure the two remaining switches on the line. I'd like to use that as a key input to the planning. "Standard" model railroad switches are often too small compared to what scaled-down versions of the prototype would be for similar use cases. I plan to rectify that and use switches in the #8 to #10 range plus curves as broad as I can justify to avoid a crammed look.