Boxing clever

ASK somebody to name the most important inventions of the second half of the 20th century, and you may hear of the silicon chip, the contraceptive pill or the hydrogen bomb. Few would plump for the shipping container. Yet those humble, standard-sized steel boxes, invented in 1956 by Malcolm McLean, have changed the world. Some economists reckon the shipping container has done more for global trade than every trade agreement signed in the past 50 years.

Even revolutionary products can be improved, though, particularly after half a century of service. And, at a meeting of the American Association for the Advancement of Science held in Chicago earlier this month Stephan Lechner, of the European Commission’s Joint Research Centre in Ispra, Italy, explained how.

One idea Dr Lechner proposed is to make containers out of carbon-fibre composites. Such containers would be easier to use, because they would be lighter and also—if designed appropriately—might be folded flat when empty, saving space. Dr Lechner reckons a carbon-fibre container would need to travel only 120,000km (three times around the Earth) to prove cheaper than its steel equivalent. It would also be more secure, because it would be easier to scan without being opened.

That is an important consideration. In 2006 America’s Congress passed a law requiring all containers arriving from abroad into American ports to be scanned to make sure they do not contain anything nasty (drugs, illegal immigrants or—a particular worry—fissile material). Doing this has proved hard, though, and the deadline for compliance is constantly being pushed back. Scanning steel needs high-power X-rays, or even gamma rays. These are expensive and dangerous. Carbon-fibre could be scanned with “soft” X-rays, which are easier to generate and use.

Scanning containers to look at their contents is, though, only one aspect of security. Another is monitoring what is happening inside them. Many are already fitted with sensors that do this, but these need power and satellite- or mobile-phone connections to work. A nifty bit of physics called the piezoelectric effect, by which certain materials generate an electric current when stressed, offers a way around that. Vibration sensors (which might help spot stowaways or shifting cargo) could be powered by the very vibrations they were designed to detect. Low-powered wireless networks, supplied with electricity in a similar manner, would then relay the bad vibes to the port authorities. In a mock port built in the car park of their institute, Dr Lechner’s team have already proved the idea works in principle.

Another way to improve containers’ security is to track them properly. At the moment, according to Dr Lechner, the authorities in a given port are usually told only about a container’s most recent movements. Better to give each container a comprehensive history, recording every port it has visited and every ship that has carried it. Such data could be crunched to detect suspicious patterns: for example, a container making several apparently pointless loops to and from the same place.

Experiments on these lines are happening in seven European countries. Dr Lechner says inspections do indeed uncover something untoward in about a fifth of the containers flagged as suspicious. The system also saves on shoe leather, since most of the work is done from an office. Containerisation put many longshoremen out of a job. Carbon-fibre containers, fitted with sensors, a travel history and the ability to talk to the authorities, may one day do the same for many customs officials.