https://newatlas.com/urban-transport/cavforth-autonomous-passenger-bus-road-testing/

QuoteThe pilot project will see five single-deck SAE Level 4 autonomous Dennis Enviro200 buses rolling over the Firth of Forth via the 1.5-mile-long (2.5-km) Forth Road Bridge to carry passengers between Ferrytool Park & Ride in Fife and the Edinburgh Train and Tram interchange.

Interesting choice.

Date revealed for groundbreaking first 'driverless' bus service over Forth Bridge | Fife Today

https://www.fifetoday.co.uk/news/transport/date-revealed-for-groundbreaking-first-driverless-bus-service-over-forth-bridge-4091317

The proposed 14-mile route from Ferrytoll Park and Ride in Fife to Edinburgh Park Transport Interchange has also been extended into Dunfermline city centre.

TLDR:  a "safety driver" behind the wheel who guides the bus on the twists and turns.

Edinburgh: 'World's first' driverless bus service doesn't quite live up to the hype

https://news.sky.com/story/edinburgh-worlds-first-driverless-bus-service-doesnt-quite-live-up-to-the-hype-12878530