Whenever I make the case for starting in the depot, someone asks whether it means giving up on the real prize — autonomous buses carrying passengers on public roads. It's a fair question, and the answer is the opposite of what they expect. Depot-first isn't a detour around street autonomy. It's the on-ramp to it.
Let me explain why these two things are one journey, not two.
Start with the technical approach. Depot autonomy and road autonomy are not separate categories built on entirely separate technology. They draw on a similar approach and many of the same building blocks: reliable drive-by-wire systems, clean interfaces between the vehicle and the autonomous-driving software, and fail-safe behaviours that are tested, monitored and repeatable — even though driving on the open road is a considerably more demanding domain. The Tier-1 suppliers who build steering, braking and driveline systems across Europe's bus platforms see it this way too — depot automation as the first stage of a progressive deployment path, building on the same core capabilities. When you deploy a smartbus in a depot, you're not building a dead-end product. You're putting the first building blocks of road autonomy into real operation.
Now the part that actually unlocks the future: evidence.
The single biggest barrier to broader autonomous operation isn't the engineering — it's the safety case. Regulators and operators need to approve wider operational domains, and to do that they need a body of demonstrated, real-world performance. Where does that evidence come from? The depot. The depot is where the first generation of autonomous buses logs real operating hours — and every one of those hours becomes a traceable record: how the system detects hazards, how it behaves at the boundary of its operating conditions, how it executes a validated minimal-risk manoeuvre under real variability of layout, weather and traffic. That accumulated record is precisely what strengthens the safety case needed to expand the domain — first to mixed depot traffic with people and conventional buses, then beyond the fence.
This is why I think of the depot as a bridge, not a destination. It connects today's constrained operations to the next era of public transport. And critically, it's a bridge you can afford to cross, because the operational savings fund the journey. You're not paying to gather evidence as a research cost. The evidence is a by-product of a deployment that's already paying for itself in recovered driver time. The learning is financed by the saving.
The policy environment is moving in the same direction, and faster than many operators realise. Switzerland, for instance, has had a regulatory framework for driverless operation on public roads — Level 4, on predefined routes, with remote supervision — since March 2025. The depot is where an operator builds the operational experience and the performance record needed to step into a framework like that with confidence. Meanwhile, the EU AI Act's requirements for high-risk AI systems — transparency, human oversight, data quality, robustness, cybersecurity — will apply to autonomous vehicle functions, depot included. Systems deployed now under structured validation, independent assessment and documented operational design domains are exactly the ones positioned to meet what's coming. Deploying today isn't jumping the gun. It's building the institutional knowledge, the data and the safety record that regulatory compliance will demand tomorrow.
So when you put a smartbus to work in your depot, here's what you're really doing. You're solving a concrete operational problem today — recovered hours, fewer collisions, lower energy cost. And at the same time, almost for free, you're laying down the building blocks, the operating experience and the evidence base for whatever comes next, whenever your city, your network and the regulatory framework are ready for it.
Most people agree autonomous vehicles are part of the future of mobility; the visibility of robotaxis has made that feel inevitable. The open question has always been what it means for public transport. This is the answer. There's a way to adopt autonomy that makes business sense from day one — start in a controlled, safe environment, prove it, earn the evidence, and let the savings finance the learning. You don't have to wait for the future to arrive. You can build toward it on someone else's timetable while improving your operation on your own.
The depot is the bridge. The street is on the other side of it.
The full trajectory — the shared building blocks, the regulatory outlook, and how depot evidence supports broader deployment — is in The State of Smart Depots 2026.