Actions of consequence

Materials World magazine
,
9 Jun 2014
Traffic jam on the M25

Despite the price of diesel cars, their fuel economy has stimulated many motorists to opt for this form of transport.

Around town, the diesel cannot be beaten except, perhaps, by even more expensive hybrid vehicles, where there is more to the concept than just supplementing a petrol engine with a battery and an electric motor. Governments, too, have been four square behind diesels, which, on balance, minimise CO2 emissions. Even in Britain, where fuel duty is as high for diesel as for petrol, sales of diesel cars are now outpacing those of petrol.

But the Jeremiahs who have been telling us that diesel is not good for the environment are being proved right. In April 2014, pollution in London, in part a result of diesel particulates, hit such high levels that politicians suggested people with heart and lung conditions should avoid strenuous activity outdoors. The Law of Unintended Consequences was in full swing. Efforts to combat global warming were having a more immediate impact on the health of our capital city. Parisian politicians took a more aggressive line, decreeing cars could only be driven on alternate days, based on their number plates. You might think diesel pollution is nothing to do with materials technology. If so, you are wrong. Pollution from the private car is as much to do with numbers as with fuels and engines. Britain has almost 30 million cars on the road, which compares with eight million back in 1964, when I passed my driving test.

How has this increase come about? Some would claim it is the relative cheapening of motor vehicles, but there is a deeper cause. It is, again, our unwelcome sidekick – the Law of Unintended Consequences. Today, the average car has a life expectancy of about 14 years. Back in the early 1960s, when vehicles were sold without undersealing, car life was a derisory six years. Car ownership was spreading, but most cars were parked on the streets, so underbody corrosion was at work from the moment a car left the production line. A query posed by UR Evans, the man who established corrosion as a science, was whether rust could breed rust. It was certainly not an academic question to me, where, after of three years of on-street parking, I noticed a slight blistering of the paint on the wings of my Ford Anglia. Probing with a screwdriver revealed that the paint was holding in place a thick layer of rust. The true scale of the problem was a fist-sized hole. So I set off to buy plastic filler, fibreglass, catalytic resin, and cans of spray paint to camouflage the damage. This was followed by hours of filling, grinding, smoothing and painting. The struggle was hopeless. Eventually I was spending more time on the bodywork than on servicing.

Car manufactures were dismissive of the issue. Prospective owners were supposed to be happy spending half their annual income on what were veritable rot boxes. The much-vaunted Mini had joints between the bodywork panels, making ideal sites for crevice corrosion. Ford boasted that it had got the sheet steel for its cars down to 0.78mm.

It was Saab, one of the most innovative of manufacturers, which was the first to market cars that were undersealed. Over the next decade, kicking and screaming, other car makers were dragged into line, as the public demanded cars that would last. One wonders, however, how many cars would now be on British roads if the time from build-to-scrap had stayed at six years. Statistical projections in the 1960s suggested 15 million – less than half the present number. And how many would have been diesels, given that the diesel only makes financial sense in a high mileage vehicle?

So shame on you, the backroom girls and boys in the anticorrosion labs of the car industry. Did you not consider the implications of what you were doing? Filling the M25 with near continuous traffic jams? And, although, as the song says, it’s very nice to go travelling, in London, Paris or Rome, the next time you are coughing out your lungs in those cities, you will know where the blame should really lie.