The use of the word “Gage” in the context of this report is wrong, pure and simple. I don’t care what FRA 213.53 says, this is the wrong word to use to describe the space between the rails.
FROM GRAMMAR.COM
The word "gage" stands for pledge. It is defined as a guarantee given against an obligation. It is regarded as a security, whether it is for a bet, for an organization or for a bank. At the same time, though, "gage" can also be used to express a challenge, in the sense of a fight.
Example 1: "Her father's apartment is her gage for the bank." - a gage practically serves as a guarantee for a loan.
Example 2: "Throw up your gage" - this is an expression meaning to forfeit a fight or to avoid a challenge.
The word "gauge", on the other hand, is used both as a noun and as a verb. As a verb, "gauge" refers to measuring, estimating, analyzing or evaluating dimensions. Whereas used as a noun, "gauge" stands for the actual dimension, usually a conventional, standard capacity of quantity. In addition, "gauge" can also be sometimes used as a noun referring to a measurement tool used for the measurement of fuel, oil, pressure and so on.
Example 3: "The NASA staff is trained to gauge the proximity of stars, planets and other elements of the galaxy." - used as a verb, it stands for estimating/evaluating/measuring a distance.
Example 4: "They estimated the thickness of the material to get slightly over 30 gauge." - as a noun, it often stands for the thickness or size of an element.
Example 5: "The fuel gauge was indicating some low values." - "gauge" can also refer to a measuring tool, as a noun.
When do we use "gage"?
Almost never. This word is considered obsolete in modern times and can easily be replaced by other words. So avoiding it would be the safest decision for both linguistic elegance and respect of formal vocabulary nowadays. Using "gage", anyway, is mostly appropriate in the examples discussed above, as a noun.
I dont believe everything I read, especially things published in government publications.