Charles, it's no good measuring the floorboards in your house, the flooring in the TSBD is industrial, not domestic. Also, those pipes are definitely not conduit. I really don't understand why you guys are still struggling with this. You have the best standard measurement possible in the photo. As I posted earlier, 3no vertical courses of bricks plus cement bed is between 8''-8.5''. Now all you need to do is measure the 3no courses on your monitors with a small compass set and all the other measurements, floorboards, pipes etc, all fall into place. I've not done it myself but I'd be very surprised if the flooring isn't approx 6'' and the pipes 4''.
PS If you try this don't forget the first course of bricks is only half visible. Measure the three above. Good luck.
Thanks Denis, I appreciate your input. Below is a photo showing the two pipes in question. Notice that the pipe on the left of the photo has been bent twice (forming the offset) and appears to me to be EMT electrical conduit. There are no fittings at the bends. EMT conduit is typically bent in the field in this manner with EMT tubing benders. And the couplings on the pipe at the right appear to have either one or two set screws for each section of tubing that helps to hold the EMT in place within each coupling. This is a typical type of coupling that I have used many times with EMT couduit.
Also, please note the box on the floor that the sniper would have sat on is approximately 11.75" wide (see photos below).
And Jerry's post of today shows a photo of that box (see below) clearly shows that that 11.75" side of that box spans approximately 3.75 floorboards. The arithmetic indicates each board to be approximately 3.13" (thanks Jerry).