The UK's first driverless bus is being trialled for the next two weeks between Fife and Edinburgh from today.
Stagecoach is carrying out on-road testing of the full-sized autonomous bus, but without passengers on board.
It's part of preparations for the launch of the CAVForth pilot service in late summer.
Five single-deck autonomous buses, operating at SAE Level 4, are running between Ferrytoll Park and Ride near Inverkeithing and the Edinburgh Park train and tram interchange, via the Forth Road Bridge, during the next fortnight.
The Perth based bus firm is working in partnership with Alexander Dennis, Fusion Processing and Transport Scotland.
Fusion Processing’s ground-breaking sensor and control technology, CAVstar, are fitted into the buses.
It'll allow the vehicles to run on pre-selected roads without the safety driver having to intervene or take control.
The buses will provide a service capable of carrying up to 36 passengers over the 14 miles across the bridge, with capacity for over 10,000 passengers per week.
This on-road testing follows successful depot-based trials, track testing and virtual simulation where the buses have been put through their paces to fine tune the autonomous drive systems.
Transport Scotland recently opened a section of Actively Managed Hard Shoulder for all buses on the M8 eastbound to help support the delivery of Project CAVForth.
It aims to reduce journey times and improve journey time reliability for all buses of 24 seats or more on approach to Scotland's capital city.
Sam Greer, Regional Director for Stagecoach in Scotland, said: "Stagecoach is continuing to look for ways to improve the service it offers to customers, including through major investment in new technology, such as the CAVForth pilot.
"This is a hugely exciting project for Scotland and we are pleased to be starting live testing on roads this week.
"This is a major step forward in our journey to fully launch the UK’s first full-sized autonomous bus service and will provide easy access to a brand-new bus route in the heart of East Scotland."
Chris Gall, ADL Group Engineering Director, said: "The start of on-route testing is a milestone for our autonomous bus project.
"In partnership with Stagecoach, Fusion Processing and Transport Scotland, project CAVForth helps us to explore new technologies that will make buses even safer and even more efficient.
"As we move towards passenger services later in the year, the project will be a landmark demonstration of future technologies in transport."
Jim Hutchinson, Fusion Processing Ltd CEO, said: "We are delighted to be leading the world’s most complex and ambitious autonomous vehicle programme.
"CAVForth will provide a useful service to local people as well as being a great demonstration of Fusion’s automated vehicle technology.
"The buses are fitted with CAVstar, our automated driving system which combines our own hardware and software to create, safe, full-size buses, operating at SAE Level 4.
"On road testing is an exciting milestone in the development of autonomous commercial vehicles and we look forward to welcoming passengers onboard in a few months’ time."
As part of project CAVForth, around 500 members of the public have helped with the implementation of the new autonomous bus service, giving feedback on what would make them feel comfortable and confident in travelling.
Built on the feedback received, the partners have developed a vision for the new autonomous vehicles, which includes making sure future autonomous bus services will still have a member of staff on board.
In a further positive step forward in the project, more than 20 specially trained "Autonomous Bus Professionals" are soon to be recruited by Stagecoach from across its East Scotland business.
When the service goes live, these experienced bus drivers will monitor the autonomous system alongside a bus "Captain" who will move around the saloon, chatting to passengers about the service and answering any questions they may have, demonstrating what a future service might feel like when the staff member is able to leave the cab while the computer does the driving.