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61fce59

Here. That's the Transport Act B.E. 2497 (1954): §12 lets the committee set routes and how many operators get licensed, via Gazette notice. So the route announcements after it should show how routes changed. Want me to dig into those?
On text: old PDFs are image-only scans, no text layer. The 2021 reform one has real text. Dataset OCR starts 2002. So the text era is ~2002+, roughly 3k notices. Notes are in NOTES.md in the repo.
Can we make like a database of a changelog of each bus route? So given a route, we can see when it was established, when was it revised, etc. with deep links into the PDF.
Known wart, see the Bangkok route 1 shot: air-con ปอ. 1 and ordinary 1 share a page, and the 2021 reform's numbers (4-70E, 5-1) are in the same list. Next could be: split those, then use text layers for the body-only notices. Which first?
Wart? Elaborate pls

commit 61fce59

Wart = known flaw. Bangkok "route 1" page mixes 3 different things: air-con ปอ.1 คลองจั่น-ปากคลองตลาด (1978, 1982), ordinary สาย 1 ถนนตก-ท่าเตียน (2007), and the 2021 reform notice.
That 2021 one is your reform PDF: it sets 258 routes, but the title only names "สายที่ 1 บางเขน-หัวลำโพง ฯลฯ", so only route 1 gets it. Fix: key air-con routes separately (ปอ.) and read the reform's route table from its text layer.
Also: I show 1978 as "ปอ.1 renumbered to 12", but ปอ.1 still exists in 1982, so it's probably a split (Sukhumvit vs New Phetchaburi). Titles alone can't tell; the body would.