Would whistle post have been found in the right of way between double-track mains or would a single one on the outside of a right-hand main been the standard?
Your right Keith, only on the outsides, nothing between the mains. "Right hand side as seen by passing train" Frisco didn't have very much two main track, some directional E&W abs, but that would hold true for sidings also. The older track was 13.6 feet to 15 feet center to center. Not much room for signs.
William is correct that the whistle boards were on the outside of the tracks. This held true for a siding and main track and for two main tracks signaled in both directions. I can't speak to current of traffic double track mains which were run directionally with a train running against the current of traffic. We had current of traffic rules in the rule book, but I didn't see any. All of our two main tracks were CTC on the Cherokee and Creek subdivisions where I ran from June 1971 on. Someone else will have to speak to that the current of traffic situations, if in fact, the Frisco had any. Terry
The only double track ABS territory I know of was St. Louis-West. We retired a bridge up their once upon a time.