Fairfax Media reported a claim recently that self-driving cars could be “mainstream in Australia within a generation” and could slash the road toll by 80 per cent (Driverless cars closer than you think).

Risk consultant Mike Erskine told a transport conference in Victoria the technology necessary for autonomous cars to operate on public roads was already well advanced. He said it would:

… come into use in some form over the next 10 to 15 years and engineering controls, when developed well, usually have something like 10 times the reliability of what a person can do for a task. Experts know human error is to blame for about 95 per cent of collisions on the road

While advanced technologies are already appearing on the market, a generation sounds awfully optimistic to me. I don’t doubt, though, that driverless cars (aka autonomous cars) are on their way and will have a profound impact on the way we plan and manage our cities (1). Google expects to release its autonomous vehicle technology in five years and GM, Audi, Nissan and BMW all expect to have driverless cars on the road by 2020. Even if we add on an extra 20 years for hyperbole, it’s an idea whose time seems close – certainly within strategic planning time frames.

Yet even though they ostensibly look up to 40 years ahead, neither Sydney’s (still) draft metropolitan strategy nor Melbourne’s (finally) finalised strategic plan, Plan Melbourne, seriously discuss how autonomous cars might affect their development in the long-term (see Should strategic planning ignore the future?). From today’s perspective there are still big questions about the outlook and the ramifications of autonomous vehicles, but it’s a very big call to assume by omission that autonomous vehicles will have no impact on the shape and operations of cities by the middle of the century.

This is an important issue but it’s also a complex one. There’re lots of claims, both positive and negative, that warrant close scrutiny. I’ve discussed autonomous cars a number of times before, so I want to revisit what I said a bit over a year ago in Could driverless cars reshape our cities? (2)

Transition and implementation

A lot of the discussion on driverless cars focuses on the considerable problems of implementation, particularly the transition period during which human-controlled vehicles are likely to share road space with machine-controlled vehicles. This could take decades, so there’re bound to be serious problems. Some of them will be technical but most will be political. What would the reaction be, for example, the first time an autonomous vehicle collides with a pedestrian?

I think there’s a parallel here with the introduction of cars at the end of the 19th century. Back then it wasn’t obvious cars would succeed on the scale they ultimately did. They were expensive to buy and operate for all other than the extremely rich. There was limited supporting infrastructure such as fuel stations and all-weather roads. The vehicles themselves were mechanically unreliable, difficult to control and operate, and unsafe for occupants. They were seen as a serious threat to pedestrians and horses as they were capable of what must’ve seemed incomprehensible speeds.

Moreover, there was active opposition to cars. As Aaron Wiener notes in the Washington City Paper:

….in the early days of the automobile, when the technology itself was being questioned and few rules existed to govern traffic and parking, there really was a war on cars. Driving could get you arrested in some places, whacked with stones in others, and actually shot by gun-wielding police in at least one. This wasn’t a philosophical debate over parking or bike lanes. It was a real, knock-down, drag-out battle.

I don’t think autonomous cars will provide the same quantum leap in mobility and productivity that cars and trucks offered back in the early 20th century, but it seems likely they’ll nevertheless offer a compelling, even irresistible, proposition.

Potential benefits

Subject to the technical problems being overcome, the positive view of fully autonomous cars is they have the potential to lower the capital and operating costs of travel, increase speeds, and make time spent in-vehicle more productive and more comfortable.

Since intelligent vehicles are much less likely to have accidents than human-controlled vehicles, they could be considerably lighter. They could consequently be cheaper to make, use less fuel and be more amenable to alternative power systems. They could be faster, too, because inter-connected computers can manage higher speeds better than humans. They could also manage congested traffic conditions intelligently.

Since they won’t require a driver, passengers could spend time working, reading, drinking or sleeping. People who currently can’t drive – like the young, the elderly, the infirm and the drunk – could enjoy greatly enhanced mobility.

Autonomous cars could spend less time searching for parking spaces; they could drop passengers at their destination and then take themselves to the nearest car park. Probably the most cited potential benefit is greater road capacity. Because autonomous cars can travel faster and closer together, roads could take more vehicles, delaying the need for additional infrastructure.

Some of the biggest benefits could potentially come from car-sharing. Rather than own one or more vehicles that sit parked most of the time, households could summon a rented vehicle as and when needed, much as they currently use a taxi. And of course, as Mr Erskine says, there could potentially be many fewer accidents due to eliminating human error.

Car-sharing isn’t an inevitable way autonomous cars would be deployed but they make the possibility plausible. Sharing would save households money, and lower-income travellers could avoid the capital cost hurdle of car ownership. For the society as a whole, sharing would reduce the number of vehicles that have to be manufactured and the number of parking spaces required in sought-after locations. Since the majority of trips involve only one or two people, the average size of the vehicle fleet could also be smaller and lighter.

Autonomous cars won’t eliminate traffic congestion. Nor will they obviate the need for public transport in dense locations, but they could make it cheaper by eliminating the expense of drivers. That would also be true for trucks, delivery vans and buses (there are already a number of rail systems with driverless trains).

Potential downsides

But there could also be problems. If travel is cheaper, faster and more comfortable, it lowers the cost of ‘driving’ ever further. People can consequently live further from work and other key destinations. That’s how trains and trams, and subsequently cars, facilitated suburban sprawl. Easier travel provides a private benefit – it increases the range of housing/locational choices available in terms of space, amenity and affordability, as well as easing pressure for redevelopment within established areas. But as we know from the history of urban sprawl over a century and a half, it can also impose social costs.

Autonomous cars could increase travel in other ways, too. Even trivial decisions could lead to more travel – for example, some households might order the car to do multiple automated shopping trips on a just-in-time  basis rather than do all shopping in one trip. Those whose travel options are currently restricted because they can’t drive would likely travel more; that’s mostly a private benefit but could have a social cost.

Another issue is that the potential for sharing autonomous cars might be more limited than much of the discussion assumes. Many travellers might prefer to have their own driverless car. They might not be prepared to wait for a shared vehicle to be dispatched or they might like the customisation potential a dedicated vehicle offers.

Even if the technology is only a generation away, fully achieving most of the positives rests on the assumption that all cars are autonomous and are supported by complementary infrastructure and laws (3). However, it’s likely the potential benefits will be seriously compromised while driver-controlled vehicles remain in the fleet. The transition to a fully autonomous fleet will likely be a challenging period politically, but policy-makers should be thinking now about the implications for the way cities might work in the future.

1. I’m assuming Mr Erskine was talking about a population generation, not a technology generation.

2. This article was previously published in a slightly different form at The Urbanist on 22 April 2013 as Could driverless cars reshape our cities?

3. That’s a key reason why “closed” systems like rail lines have seen the first implementations of driverless technology.

This article was first published at Crikey.