MY MOTHER, who in the autumn of her years still goes by bicycle to do her shopping at Sainsbury’s in Cromwell Road, in London enjoys a modest proposal about road safety. Outlaw seatbelts. Instead, fit a large spike to every steering wheel, pointed towards the driver’s chest. Well, this idea of the risk expert, John Adams, of University College London, may never catch on. But like Swift’s modest proposal to end child poverty by eating poor children, it would solve the problem. Drivers would take more care, and an innocent cycle ride to a supermarket would be much less hazardous.

Like any sound satire the proposal has good sense behind it. Mountaineering is dangerous, but climbers rarely fall on anyone else. Atlantic cod is the product of a hazardous industry, but the risks are borne by men who have chosen to accept them with their pay packets. Fair enough. But with cars it does not work like that. In the road safety numbers, published yesterday, you can discover that for every two people who died driving a car, one person got run over.

In cost-benefit terms, motoring is a dog’s breakfast. You get in your car; you know it is hazardous; but the risk of death is the cost of comfortable travel, and you accept that. What you did not know is that you are getting a subsidy. The boy playing footie in his street, the merchant banker coming out of the Tube, or for that matter my mother with her panniers full of organic lettuce, are bearing risks created by your travel happiness. One third of your risk is suffered by someone who is not getting anything in return.

Any economist will tell you that where benefits go to people who do not bear the costs, wrong choices get made. Airbags and crumple zones create a sense of invulnerability in the driver.

Worse, this sense is not illusory. I can drive more recklessly in a Volvo than in a Morris Minor, without taking any more risks. For the poor mug on the pavement or in the cycle lane, though, it makes no odds whether I have a side- impact protection system. It is a ton of steel or more at 40mph either way. The safer I feel, the faster I drive, the more likely I am to run you down.

Road safety is just one egregious example of the confused incentives in which all motoring is clouded. Driving costs a lot, but you pay for much of it when you fork out for tax and insurance. Every hundred miles you drive costs you £41, but you take only a quarter of that out of your wallet at the point of deciding whether to make the trip by buying petrol.

Poor old Thomas the Tank Engine is cheaper all round, but the punter pays something close to the full cost of the journey every time he steps on to the platform. This is the real reason for congestion charging and road tolls and higher fuel duty. Not to punish the motorist, but to help us read the price tag for each journey we make. Driving is not wicked, but we do more of it than makes us happy, because what we pay for it today does not tell us how much it costs over a lifetime. In much the same way, people smoked more before they knew it would kill them.

Of course, many of the solutions are worse than the problem. One of the worst by-products of motoring is a hideous body of costly, unenforceable laws which lower the respect in which the law is held. Multiplying laws, even to untangle cost and benefit in the motoring economy — that way madness lies. We might try pay-as-you-drive insurance, with which some insurers are experimenting already, or even plough road charges back into subsidising third- party cover. Or how about making it harder to insure the car against every last ding or crunch, and bring the cost of any journey closer to the lifetime cost by cutting down the upfront premiums. It might make drivers warier, without resorting to the spike.

One thing is certain though: the less driving we do, the less we will want to do. Often one gets in a car because it is the only place free from the stink and racket of other cars, and safe from the alienated anger of other drivers. To this extent, driving is a sad but apt metaphor for the mental condition of our times. We are at odds with one another because my pursuing my own personal fulfilment goads you to pursue yours, and vice versa; we hide in sealed capsules that make us less worth finding; we wear armour because everyone else is wearing armour. That is the real hidden cost of motoring.

The author’s latest book Persuading People to be Good is about the philosopher Alasdair MacIntyre

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