Modern Canadian Practice
The article on maintenance flags reflects modern Canadian practice and US practice is a bit different.
The use of flags to protect track work only goes back to the 1960's or so. Rule books prior to that have no mention of using flag to protect track workers. The use of the yellow-red flag goes back to the 1980's, prior to that most US roads only used yellow flags.
US flags were on short (3-4 foot tall) single posts until the 1990's or later when they went to taller posts.
US practice was to put a yellow flag 2 miles from the beginning of the temporary speed restriction or work area. If it was for worker protection there would be a red flag if the track was to be fouled at the beginning of the work area, if it was a slow order there was no flag at the beginning of the speed restriction. At the end of the work area or speed restriction there would be a green flag.
Beginning in the 1980 or 1990's in the US railroads gradually changed over to a yellow red flag for track worker protection. That was a flag divided into quarters diagonally with alternating quadrants yellow and red. The plain yellow flag was only used for temporary speed restrictions. In the late 1990's the rules changed to require a stop flag be used with a yellow red flag. Prior to that the stop was optional.
The backs of the signs are NOT painted. That eliminates confusion over the start of the restriction. Normally they are plain aluminum. I think the author meant picture #13 to mean the end of a speed restriction where viewer/camera/train is approaching the beginning of a temporary speed restriction with the yellow flag marking the beginning for trains in the viewers direction and the green flag marking the end of the restrictionfor trains coming towards the viewer. What that actually tells me is that I am in a speed restriction and once I pass the green flag I will be out of the speed restriction, plus there is another speed restriction two miles from the yellow flag.
The blue flag is not a "maintenance" flag its a mechanical department flag. Two different groups. The blue flag protects workers on, under or about the rolling equipment. Technically it should only be used to protect railroad workers. Many industries use a blue flag on their tracks although technically they should be using a white flag. The blue flag on page 84 could be considered not in compliance with the rules since it appears to be protecting equipment, not mechanical dept. workers (they probably should be using a red stop flag).
If I were going to use these flags I would pick a "flagging distance" depending on the size of my layout (2 feet, 4 feet, a train length, etc). I would put the yellow or yellow red flags that flagging distance on either side of the restriction and then a green flag at the other end. If it was to protect workers then a red flag at the beginning would be appropriate.
Another caveat is that you would have to give the train crews an order or bulletin for each of these restrictions. Temporary speed restrictions are listed on Form X (train orders) or Form A (track warrants/bulletins). Worker protections are listed on Form Y (train orders) or Form B (track warrants/bulletins).
