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­­­Will self-driving cars really be a cure-all for transport problems? Don’t be silly

Iain Reeve
18 August 2017
Iain Reeve
Iain Reeve


Whenever we talk about autonomous vehicles, a little alarm bell goes off in my head. No, not the safety one – I am sure that boffins in white coats with pens in their top pockets will sort out the safety issues. We will probably all be safer with the Terminator driving behind us, rather than with the human idiot who decides that he has an unnatural fondness for my back bumper at 70mph on the M25.

The little mental alarm bell is the one that sounds whenever we’re getting too excited by geekiness. Self-driving cars will cure congestion, they say. We will be able to drive in huge road trains, with only a few inches between us. Self-driving cars will cure our parking woes. We won’t own a car. We will just whistle for one by phones and it will come running to us like a faithful dog hearing the magic word “walkies”. We won’t need to go to the shops. We’ll be able to work in our cars. We will save the planet.

“They” are saying a lot. And that makes me nervous. Because “they” aren’t always right.

I am old enough to remember a time before the internet. On my first day in the Department of Transport, on  1 August 1985, I was given a collection of pens, an in-tray, half a dozen envelopes to send drafts to the typing pool, and a rotary dial telephone.

That was it. No computer. No screen. No emails. No way of sending pictures of cats to my friends.

Within a few years, “they” were telling me that the internet was going to change my life. We wouldn’t need to go to places because we would be video conferencing all the time. We wouldn’t send drafts to the typing pool. We’d be sending emails. And with all that precious time that we saved, we would have a better life. We would have lots of free time to write poetry, climb mountains, learn to play the guitar, make love, or start a new company exporting home-made soup. And all before lunch. Yeah, right.

As it turned out, Parkinson’s law still applies. Work expands to fill the time available for its completion. Parkinson meant it as a joke, but it has proved to be eerily accurate. I would add another thought, humbly entitled Reeve’s First Law: “Work expands to fill the technology available for its completion.”

The internet didn’t give us the paperless office and free time nirvana that we were promised. Instead we found new ways to use that extra time. We argued about Brexit. We played Tetris and Angry Birds. Our boss sent us work at ten o’clock at night. 

It is at this point that I need to mention Marchetti’s constant. Italian physicist Cesare Marchetti argued that most people have an in-built time budget for travel. We are all prepared to travel for around an hour a day. If transport systems improve, we don’t use the free time for other things. We change our travel patterns so that we are still using that magic hour. This has apparently been the same since Neolithic times. 

It can be a sobering thought for those of us in the transport profession. If we build a faster road, the public won’t simply bank all those time savings and write us endless letters of thanks. No, they will up-sticks and buy a house further away from their work. Or take a job further away from where they live. And then they will start complaining again. The ungrateful so-and-so’s.

What happens if we pass self-driving cars through Marchetti’s constant? It’s not all good news, I’m afraid.

If we give people faster journeys, then over time they will travel further. The total time spent travelling will not change.

If we allow people to work while they are driving, they will also probably travel further.

If we free up some parking spaces by reducing car ownership, some or all of those parking spaces will be filled by new drivers and car owners.

If we create more road capacity through road trains, more people will drive to take advantage of that extra capacity.

I can imagine that the cheerleaders for self-drive cars will be pretty annoyed around now. They’ll no doubt be reaching for their keyboards to say this Reeve bloke is utterly wrong. 

I am sure that self-driving cars will change the way we travel. They may make some journeys quicker, easier and safer. They will allow some people to drive who would not otherwise be able to. They will allow for more deliveries without the need to employ someone.

But let’s not assume that the public will use this extra time for writing poetry and making things. Empty roads do not stay empty for long.

And remember my little geek bell. If someone ever tries to tell you that a new technology will change the world, be afraid. Because the world has a funny habit of changing right back. The public will take all the advantages that you throw at them, normalise those advantages and then ask for some more.

Do self-driving cars work? Yes.

Are self-driving cars coming? Yes.

Are they a good thing? Yes and no.


Iain Reeve is a transport policy consultant

Email: [email protected] //

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