Commit

ee67650

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?
General sense, ~8k route notices: 1954 committee 838 (1955–79). After the 1979 act: central board 2,533 (1980–now), provincial boards 4,593 across 80 provinces. Peaks in the 80s–00s, then a 2020s burst (the reform). Mostly "revise" 3.9k, "establish" 3.1k, "cancel" 850.

commit ee67650