Sadiq Khan Wants a Cap on London Robotaxis. Here Is What It Could Mean for Drivers

Imagine sitting in a queue on the Embankment and noticing that the car beside you, an empty one, has nobody in the driving seat. Now imagine that being normal, with hundreds of them circulating, picking up and dropping off wherever the kerb allows.

That is the future London's mayor is wary of. According to The Guardian, Sadiq Khan has called for a limit on the number of robotaxis allowed on the capital's streets, just as the government moves towards allowing driverless vehicles in London. His stated concerns are congestion, air quality and jobs.

Most coverage will focus on the technology. This post looks at the less glamorous questions that decide how it plays out for ordinary drivers: who can actually impose a cap, how robotaxis would sit within existing traffic rules, and what you should keep in mind as a motorist.

What happened

The Guardian reports that the mayor wants a ceiling on robotaxi numbers rather than a free-for-all. The call comes as ministers edge towards letting driverless vehicles operate commercially in the capital. The three worries cited are:

• Congestion: more vehicles on already crowded roads.
• Air quality: a concern even if the vehicles are electric, as we explain below.
• Jobs: the livelihoods of London's licensed taxi and private hire drivers.

That is the core of the story. The rest of this piece is our analysis of why those three points matter and where the law stands.

Why the congestion argument is not as simple as it sounds

The intuitive pitch for robotaxis is that they replace private car ownership, so fewer cars overall. The mayor's worry is the opposite scenario, and it has some logic to it.

Empty running. A conventional private car sits parked for most of its life. A robotaxi is only earning when it is moving, which gives its operator a commercial incentive to keep it circulating. When no passenger is aboard, it may still be driving towards the next pick-up, or cruising until it is needed. Human minicab drivers do this too, but a fleet operator can add vehicles far more easily than recruiting and licensing new drivers.

Cheap rides draw people off buses. If robotaxi fares were low, some journeys that currently go by bus, Tube or on foot could move to cars. We do not have figures on how this would play out in London, and we are not going to invent any. It is, however, a standard concern in transport planning and a plausible reading of why the mayor wants a cap rather than a ban.

Kerbside chaos. Pick-ups and drop-offs happen at the kerb. In a city where kerb space is already contested between loading bays, bus stops, cycle lanes, resident bays and red routes, a surge in vehicles stopping for passengers could add friction. If you have read our guide to red route parking rules, you will know how tightly stopping is controlled on those roads.

The air quality question

An electric robotaxi has no exhaust emissions, so why would air quality be a concern? Because tailpipes are not the only source of road pollution. Brake and tyre wear and road dust still produce particulates, and more vehicle-miles generally means more of them. The mayor's argument appears to be about total traffic volume rather than the fuel type, though the source summary does not go into detail, so we will not put words in his mouth.

It also ties into London's wider clean air policy. If you want the background on how that has played out, our piece on ULEZ expansion three years on is a good place to start.

The jobs angle

London has a long-established licensed trade. Black cab drivers famously complete the Knowledge, and tens of thousands of private hire drivers work through app platforms. A large fleet of driverless vehicles competing for the same fares is an obvious threat to those incomes.

This is where politics and licensing law meet, which brings us to the legal question.

The legal angle: who can actually cap robotaxis?

A mayor calling for a cap is not the same as a mayor having the power to impose one. Three pieces of law are worth understanding.

1. The Automated Vehicles Act 2024

This Act is the main framework for self-driving vehicles in Great Britain. In broad terms it creates a system of authorisation for self-driving vehicles and puts legal responsibility on the company behind the driving system, rather than on a passenger who is not actually driving. It also provides for a permitting scheme for automated passenger services, the category into which commercial robotaxis would fall.

Our understanding is that the permitting scheme gives local transport authorities a role, with Transport for London involved in the capital. The detail of how much weight TfL's consent carries, and how the government's accelerated pilot plans interact with that, is exactly what the cap debate is likely to turn on. Readers should treat the specifics as evolving and check official government and TfL announcements.

2. Private hire licensing in London

Taxis and private hire vehicles in London are licensed by TfL, under different legislation. As a general rule, London's licensing regime for private hire has not allowed TfL to limit the number of private hire vehicles simply because there are too many. Sadiq Khan has previously pressed for stronger powers over private hire numbers, and the government has historically been reluctant to grant them. If robotaxis are treated as private hire services, the mayor may find that a cap needs new legal powers rather than just a policy preference. That is our reading of the position, not a definitive statement, and it is the sort of point that could change if Parliament legislates.

3. Traffic and parking enforcement

Even if robotaxis arrive, they will not float above the rules. In London, councils and TfL enforce parking, bus lane, box junction and other moving traffic restrictions through civil penalty charge notices under the Traffic Management Act 2004. Those penalty charges are generally directed at the registered keeper of the vehicle. For a robotaxi, that would be the operating company rather than a passenger.

That raises an interesting practical point. Operators with large fleets and automated systems will presumably be well placed to handle appeals at scale, while individual drivers contest the same types of PCN one at a time.

What drivers should know

You do not need to own a Waymo-style fleet or drive a minicab for this to matter. Here is what it means in practice.

1. Do not assume a robotaxi will behave like a human driver. The Highway Code applies to everyone, but automated vehicles may be more cautious, stop more precisely, or react differently to unusual situations. Leave sensible gaps, avoid sudden manoeuvres around them and do not expect eye contact or hand signals to work.

2. Expect more stopping at the kerb. If pick-ups and drop-offs rise, you may encounter more vehicles pausing in places where stopping is restricted or just awkward. Do not copy them. A vehicle stopping in a restricted spot does not make it lawful for you, and a PCN lands on you regardless of what is happening around you.

3. Do not assume robotaxis have the same privileges as black cabs. Black cabs can use many bus lanes that private hire vehicles cannot. Whether robotaxis would be treated more like private hire is a question regulators will have to settle, and signs and local rules vary by borough and road. Always read the sign, as we explain in our guide to decoding UK parking signs.

4. Know that charging zones still bite. Private hire vehicles generally pay the London Congestion Charge, with exemptions for some wheelchair-accessible vehicles, while black cabs are exempt. How the charge would apply to a robotaxi fleet is something TfL would need to confirm. For your own journeys, check the current rules on our page about the London Congestion Charge in 2026, and always verify against TfL's official site before you travel.

5. If you are in a collision with an automated vehicle, gather evidence. As with any incident, take photographs, note the vehicle's identification, exchange details with the operator or any safety driver if present, and report it to your insurer. Cameras and data from automated vehicles may be relevant, but how you get access to them will depend on the operator and the circumstances. For anything serious, seek professional advice.

6. If you drive for a living, watch the licensing consultation. Taxi and private hire drivers have the most at stake. Trade bodies and TfL consultations are the places where practical rules will be shaped, so it is worth keeping an eye on official channels.

Looking ahead

Here are the questions worth watching over the coming months.

• Will the government give London a say? The strength of the mayor's hand depends on how much control TfL has over permits for driverless passenger services. If the legal framework gives it a meaningful consent role, a cap could be written into pilot conditions, which is a more practical route than a blanket legal limit.
• Will a cap be framed as a pilot limit? Starting small, with a fixed number of vehicles in defined areas and a review before expansion, is a common way regulators test new technology. That may be the middle ground between the mayor's caution and the government's enthusiasm.
• What data will be published? Congestion and air quality claims need evidence. If trials produce credible numbers on empty running, kerbside stops and journey substitution, that will shape the debate far more than slogans. We will not guess at figures that do not exist yet.
• How will enforcement work? Expect questions about how penalty charges are issued to operators, how appeals work, and whether authorities need new tools to deal with fleets of vehicles that never get tired and never argue with a traffic warden.

For now, the sensible position for drivers is neither panic nor complacency. Driverless taxis may well become a feature of London life, but the rules around them are still being written. The mayor's call for a cap is a bid to influence those rules before they are set.

If you are unsure how any of this affects a specific penalty charge or licensing question, the best sources are TfL, the Department for Transport and GOV.UK. This article is general information, not legal advice.

Source: The Guardian, "Sadiq Khan calls for cap on numbers of robotaxis on London streets".