Business Secretary Vince Cable literally cannot wait for autonomous travel. © Rui Vieira/PA Archive/Press Association Images

I’m very excited about driverless cars. They have the potential to change a lot of what we take for granted in our economy, whether that’s how post and parcels get to our homes or how we get from our homes to our offices and schools. But the technology will develop gradually, perhaps taking as much as 20 years before it starts to transform anything. What’s supposed to happen in the meantime though is that politicians get way ahead of the feasibility studies and make rhetorical claims that are fun to debunk. Disappointingly, they’re being much more level headed.

Today the Government launched “The Pathway to Driverless Cars,” a long, careful action plan for the next several years. There were some fanciful statements. Vince Cable, the Business Secretary, said that the UK has the opportunity to place itself as a world leader in what will become a £900bn industry. That figure is more or less a complete invention. We can nit-pick the title of the report too. Most of the vehicles it envisages have a driver—indeed, the driver bears liability for any accidents that occur rather than the machine. However, on the whole the plan is informed by a sophisticated understanding of the car industry, the challenges facing “autonomous vehicles,” and what government can do about them.

The issue of liability is a big one. Let’s say Google succeeds in creating the dominant operating system for driverless cars, building on its mapping and search capabilities as well as the extensive testing it has done already in the US. Does that mean that Google is responsible every time that one of these cars has an accident? The potential scale of that liability is such that Google may rue the day it ever put a driverless car on the road. So it may be that the liability will have to be shared if this is to become a viable technology. But shared with whom—the car manufacturer, the driver or the Highways Agency? For the moment the Government strategy doesn’t state the answer. It recognises the issue though and suggests that “By Summer 2017” it will be possible to introduce new laws that sort it out.

Perhaps the biggest issue that isn’t recognised is what the introduction of driverless cars might mean for public transport infrastructure. Consider the new North-South rail link to deliver a high speed rail line between London and other major cities (at high cost.) What if by the time the line is built—roughly 20 years—driverless cars can make those journeys almost as quickly with much greater flexibility on departure and arrival times than rail can offer? One of the other advantages of rail at the moment is that people can work on trains whereas they can’t in cars. That advantage disappears if the driver doesn’t have to, well, drive—they can be reading, emailing or videoconferencing at the same time, potentially while enjoying greater privacy and comfort than a train can offer.

It would take a particularly bold politician to suggest cancelling High Speed 2 because of the emergence of driverless cars. Neither Vince Cable and Claire Perry, the Transport Minister, who launched the Government’s strategy are being as bold as that. They have played it safe. But this might be one of those rare occasions when it’s the failure by a politician to make a big, bold promise that leads to future embarrassment.