I got on a bus in Adelaide and couldn't believe what happened next: 'What's going on?'

A French expat was left shocked and confused by a popular bus route in an Australian city.

Valentin, who goes by the TikTok handle @valentinslo, boarded a bus operating on the Adelaide O-Bahn – a 12-kilometre guided bus route between the city and the north-eastern suburbs.

The O-Bahn, a concept developed in Germany, features automatic track guidance for buses and provides a faster, more cost-efficient service.

In a now viral TikTok video, he recorded his reaction as the road turned into a train-like railway line.

“Adelaide, what the hell??” he wrote in the short clip that has now been viewed more than 1.4 million times.

“Metro map makes sense, but this is so weird!”

A French expat was confused by the Adelaide O-Bahn. In a now-viral TikTok video, he captured his reaction when the road turned into a train-like railway line

Buses from 18 different routes wind through the northeastern suburbs before joining the guideway at one of two access stations.

Steering is completely controlled by the guideway and buses reach speeds of up to 100 km per hour.

Other vehicles are not supposed to access the O-Bahn, but they occasionally do so accidentally and need to be rescued.

Buses from 18 different routes wind through the northeastern suburbs before joining the guideway at one of two access stations. Steering is completely controlled by the guideway and buses reach speeds of up to 100 km per hour (stock image)

The locals responded quickly and offered explanations.

'Welcome to the O-Bahn. Please don't drive over it,” someone said.

'It's the O-Bahn. When my mother moved here from Tassie she was the first to accidentally drive her car into it and get stuck,” wrote another.

“It's great when the driver reads the paper,” said a third.

But some called it a “terrifying” experience.

South Australia is the only state and territory in Australia with the O-Bahn and it opened in 1986.