Will driverless cars save our cities, or ruin them?
Credit: John Stillwell/PA Archive

Driverless cars are coming soon, and there will be big political implications.

One set of issues revolves around road safety. Unless automated systems are much, much safer than human drivers, we won’t get driverless cars. But if the new technology does work out, then the moral case for banning human drivers – and therefore saving thousands of lives – becomes overwhelming.

This is going to be a major issue – perhaps a defining one – within one or two decades. But it won’t be the only one.

There’s the impact on transport policy – and, by extension, the way we plan and run our cities. Let’s begin with road space. At the moment, the number of vehicles on our roads are limited by the number of drivers available to drive them. Most of the time, most of us are doing something else than driving – and quite a lot of us don’t drive at all.

With automated vehicles (AVs) those limits no longer apply. In theory, the roads could be full of empty but moving cars, vans and trucks – looking for ‘fares’ like an under-employed taxi driver. The counter-argument is that under computer control, vehicles can drive in precise, compact formations in a fraction of the road space required by human drivers. Furthermore, there’d be none of the traffic congestion caused by accidents and bad driving habits such as ‘rubber-necking’ and braking too hard. Self-driving cars are also self-parking – making it easier to ban on-road parking were it does most to impede traffic flow.

However, as Jeff Speck explains in a post for the Public Square blog, more road capacity only attracts more traffic:

“…these days, traffic congestion is the principal constraint to driving. Because driving is already so subsidized, we do it as much as we can, unless we are punished by traffic…

“This becomes especially alarming when we realize that AVs will make driving cheaper in two ways: money and time. You will pay less per mile, and won’t mind sitting in gridlock as you work or watch cat videos.”

To put it another way, if a super-cheap taxi service were available wherever you went, would you spend more time on the road? Almost certainly – and that’s exactly the service that driverless vehicles will provide.

You’d probably also spend less time on public transport – which is an extra problem:

“This is why, when the Brooklyn Bridge was converted from part rail to all car in 1948, it went from carrying 400,000 people/day to carrying only 170,000 people/day.  It’s why a single New York L train carries as many people per hour as 2000 cars, and an articulated bus equals 100 cars. Autonomous cars are a great supplement to transit, but, in congested places, they are not a solution to transit.”

So is this the urban environment of the near future – a solid mass of very safe, but very slow moving traffic? Let’s hope we’ve gone all-electric by that point, or we’ll choke to death on the fumes.

There is an alternative, though – which is universal, but very flexible, road pricing. For instance, access to particularly busy parts of a local road network could become steadily more expensive until traffic speeds reached a target level. Unlike the congestion charges currently imposed in places like central London, prices could be adjusted in real time to have the desired effect – only charging people extra when and where roads become overused.

Would this mean that poorer people would be priced off the most in-demand routes? Would only the rich reap the benefits of reduced congestion? Not necessarily. The pricing system might include a daily per capita allowance of ‘road credits’ that citizens could either use themselves or sell online to others. People travelling by bus or some other shared vehicle would use up their credits at a proportionately slower rate than those hogging a whole car – and the associated road space – to themselves.

This all sounds very complicated (certainly compared to present-day congestion charges), however any technological platform capable of enabling self-driving cars could easily support an intelligent road charging scheme.

As with the issue of enforcing road safety there will be those who resent yet another restriction on the ‘freedom of the road’. However, road space isn’t free, it is a limited resource. Driverless cars will make it easier for more people to access that resource and so we will need to find a fair and efficient way of sharing it.

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