Autonomous Systems: depot-first autonomy for smartbuses

"For more than a decade, autonomous buses have been "almost ready." Demonstrations with safety drivers began around 2015, and ten years later, this is still largely what we see. The reason is not a lack of ambition - it is physics, safety, and economics. Autonomous buses on city streets are inherently difficult. They carry dozens of passengers, operate as heavy vehicles, and move through a chaotic urban environment."

"One of the key challenges is the so-called "minimal risk manoeuvre" - in plain terms, what the vehicle should do if something goes wrong. At speeds of up to 50 km/h, physics does not allow a bus to simply stop instantly. In many situations, an emergency stop would not even be desirable, especially with standing passengers on board. Autonomous systems must therefore be intelligent and reliable enough to handle emergencies."

"So far, in the case of autonomous buses, this responsibility has been pushed onto human drivers - or "safety drivers", as they are called in the autonomous vehicle world. This is a sensible approach from a safety perspective, but it fundamentally undermines the economics. You replace a driver with... a safety driver, while still paying for all the technology. A bus with a safety driver is not autonomous - it is simply a more expensive bus."

Autonomous buses have repeatedly reached demonstration stage but remain largely driver-supervised due to physical, safety, and economic constraints. Buses operate as heavy vehicles carrying dozens of passengers in chaotic urban traffic, creating challenges for the minimal risk manoeuvre since stopping quickly at up to 50 km/h is physically impossible and often unsafe for standing passengers. Safety drivers currently absorb emergency responsibility, preserving safety but eliminating cost advantages of full autonomy. Depot environments change the equation by enabling low speeds, empty vehicles, and controlled layouts where systems can react calmly and stop safely, making practical, deployable autonomy feasible for initial deployments.

Read at Sustainable Bus