Most of us have not seen an autonomous car, let alone been in one. Yet autonomous vehicles have the potential to define a new era, as private cars did a century ago.

We have heard plenty about their technologies, safety standards, and legal and ethical challenges. What we might not have considered is how this new technology, which makes them much more than just another type of car, may reshape our city, changing the streetscape and the balance between centre and suburb.

This mobility revolution has been just around the corner for a few years now. The game changers are vehicles that are fully independent within a defined geographic zone as a minimum, or of level 4 autonomy and above, and are connected to road infrastructure as well as other vehicles. Estimates vary as to when these fully autonomous vehicles (AVs) might become part of our lives. Studies vary in their estimates from 3 to 13 years, with one recent study arguing that, by 2030, 95% of all US passenger miles travelled will be served by autonomous taxis.

The UK is also working hard to prepare for this revolution, and is according to one study the 5^th most prepared country for AVs. The UK Government would like to see driverless cars on British roads by 2021, and is planning changes in regulations to encourage adoption of AVs. It has also earmarked £250M to position the UK as a global leader in Connected and Autonomous Vehicles.

But what do these developments mean for UK cities, and especially for London, a city where in 2016 public transportation modes had a share of all trips (37%) that exceeded private cars (36%) and continues to grow? How will AVs affect Londoners’ flagging relationship with private cars in a city where 43% of households do not have access to one? And how will it fit with the capital’s mobility trends?

The economics of AVs may hold a few clues to answer these questions.

To make an AV and its complex and expensive electronic systems economically viable, it needs to be utilised around the clock for most of its lifetime, far exceeding the limited utilisation rate of current private cars which currently stands at 3-5 per cent of the time. This level of utilisation can only be achieved if AVs are introduced as autonomous taxis (or, driverless electric Uber taxis if you will) operating as much as 90% of the time, requiring minimal maintenance compared to internal combustion engine (ICE) vehicles, and causing minimal damage to the city’s air quality due to the lack of tail-pipe emissions.

The impact of the Autonomous Taxis (ATs) being introduced into the public transportation mix in London could range from the complementary to the disruptive. ATs could be introduced as a flexible new mode of transport which complements the capital’s multi-modal public transportation networks in supporting door-to-door mobility. ATs could, for example, provide first-mile and last-mile connections to and from tube stations, and could respond rapidly to rising demand for mobility during peak hours. This integration could be further strengthened if the entire trip -including ATs and public transportation components – is planned, booked, and paid for using a digital platform or a mobile application.

Under this scenario, ATs would simply be integrated into the emerging trend of Mobility as a Service (MaaS), which has been successfully implemented in Helsinki and is being tested in Birmingham.

But under another scenario, the high utilisation rate of ATs could also allow the service they provide to become cost competitive with public transportation, providing door-to-door mobility at a comparable cost. This scenario – where ATs cannibalise rather than complement public transportation – could lead to significantly more AVs on London’s roads, increased traffic congestion, and potentially more carbon emissions. That depends on how successful the UK is in decarbonising its electricity grid.

Separately, AVs could also enable the emergence of autonomous freight. London has already witnessed a rise in van trips of 16% since 2001 – compared to a drop of 13% in private car use – which has been attributed to an increase in home deliveries and the large size of the UK’s e-commerce market. Here, AVs could reduce the congestion caused by these vans by facilitating off-peak deliveries (e.g. at night). Small deliveries might even be diverted away from roads if delivery drones prove safe and reliable.

Under both scenarios, AVs will require fundamental changes to the urban fabric of the city. Like the car revolution of the 20^th century, AVs will force us to reconsider the function of London’s public realm, and the urban fabric of this old city might need to be reconfigured at all scales: city, district, street, and buildings.

At city and district scales:

• The economics of ATs will work best in areas of higher population density, which could lead to further densification of central London. The expected reduction in demand for parking lots, petrol stations, and parking structures, could see their banked real estate value being released in the form of residential or commercial developments. This partially ties in with the capital’s current growth plan around dense mixed-use developments.
• Outer London boroughs might also witness densification as ATs open the potential for private commutes from the outer boroughs to central London and to rely on ATs for commuting. Some might even choose to move well outside the city – within or even beyond the green belt- benefiting from the ability to use the private ATs for work or rest during the long commute hours.
• Commuting within and between outer boroughs, which are less well served by the London Underground, could also increase due to the use of ATs. This could minimise the barriers to the development of higher density business areas in the outer boroughs, and in turn enable the emergence of multiple medium-density business centres around the city. This multi-centric city structure would not only reduce peak transportation flows in and out of central London but it could also enable the development of multiple business eco-systems around individual centres that foster collaboration and competition (in a way similar to the development of the financial services sector in the City of London, and to the development of Tech City around the Old Street Roundabout in East London).

At street scale:

• AVs can move more people in fewer vehicles on less congested streets compared to private cars. This means that some London streets could be made narrower and spare street space can be reallocated for other uses including bus lanes, cycling lanes, or expanded pavements. Street space can also be released for vegetation, allowing for cleaner streets and better storm water management. Demand for street parking could also drop due to ATs, but will be replaced by an increased need for drop-off and pick-up points (which could be priced to manage demand). These transformations will require a fundamental reconfiguration of the city’s streetscapes.
• Central London’s historic street patterns also pose some – albeit limited – challenges to the implementation of AVs, where the narrowest streets may not be able to accommodate dedicated AV lanes. As a result, AV and regular vehicle traffic would initially have to mix, thus reducing overall efficiency – due to the inability of AVs to form platoons, for example.

At building scale:

• As many parking structures and residential garages become redundant, London must facilitate their adaptation into residential or commercial uses. This requires changes to the local planning processes to facilitate change of use and densification. It also includes mandating adaptable design and additional infrastructure for new parking facilities to ensure that they can be easily converted to new uses when AVs become mainstream.

The success or failure of AVs in UK cities, would be determined not only by the viability of the technology, but by its economics, the policies ensuring their integration into existing mobility network, and the regulations governing their operation (e.g. tolling and road pricing).  It will also be determined by how successful the cities are in mitigating the social impact of a transition to AVs. There are about half a million taxi drivers, delivery drivers, and bus drivers in UK cities, the majority of whom will be impacted by the integration and adoption of AVs.

The good news is that London is in a great position to lead this complex process. Transport for London has developed one of the world’s most advanced transportation data platforms and has collected an enormous amount of data that gives us a detailed understanding of mobility in the capital. The city also has great experience in tolling, acquired from the operation of the city’s Congestion Charge zone.

The capital has grown and transformed itself many times in its long history, always embracing new technologies whilst maintaining its heritage and unique character. The AV revolution presents the latest mobility challenge to the city. It’s a challenge that might redefine the city, again.