Good friends, I give you: the about-minute.

This is not something that spun loose during translation. The "about-minute" here is a straight calque of the Japanese 約分. This sign is asserting, apparently seriously, that it is correct to say "The train ride from Yokohama to here takes twenty about-minutes", and that the same is true of the equivalent structure in Japanese.

My native-speaker sense rejects the English version -- admiring nevertheless its ingenuity -- and I have my doubts about the Japanese one, too. I can't find any websites that use "(number)約分" more than once on the same page (except for sites using it in its other sense, "reduce [a fraction"), but I can find plenty of sites with a few "約(number)分" ("about (number) minutes") and just one "(number)約分", suggesting strongly that these cases are just typos.

Still, non-standard in both English and Japanese as this usage seems to be, I think it's brilliant. "About-minutes" are bold and concrete where their insubstantial cousins, "minutes (approximate)" are timid and hypothetical. Plus, "about-minutes" are totally commutable: if you define the "about" part to mean "+/- 10%", then sixty about-minutes do indeed add up to one about-hour, and so on.

Bonus information! "About" itself exists in Japanese as a loan word: an adjective/adverb (depending on trailing particle) meaning "rough[ly]", "vague[ly]", "flexibl[y]", "half-assed[ly]"... clearly, any definition of abauto must itself be abauto, but here's a fine visual representation of the concept: a "chō abauto" floor guide for some store somewhere. (Chō means "very".)