Just Googled BNSF Track Signals and got back a hatful of images. Some would be easy to scale - measure rail width at mast, then make vertical measurements, Others might require a more comfortable knowledge of Descriptive Geometry. Subjects ranged from single and double mast mounts to a bridge over multiple tracks with 3-over-3 in both directions.
The one thing I didn't find in a rather cursory look was the BNSF Common Standard for signal installation. You might try that as a Google query.
Chuck (Modeling Central Japan in September, 1964 - color-light signals included)
This site has a simple drawing with a few basic dimensions. Don't know how close they are to BNSF signals
http://www.lwind.com/wayside_structures.html
I tried to sell my two cents worth, but no one would give me a plug nickel for it.
I don't have a leg to stand on.
Does anybody know how high (in feet) the BNSF 3 over 3 head signals are and how many feet the signal heads are from the ground or signal base? I am asking because I just bought a ton of OregonRail Supply's 3 over 3 HO scale signal kit (https://www.walthers.com/products/layout/signals-detection-units-signs/signal/block-signal-kit-three-over-three-w-leds) and I would like to know how high to make the mast and the placements of the signal heads on it.
Thank you for anyones help with this.