Microdot markers
July 15, 2011
In June, police in the Meiderich district of Duisburg were called out in force. Several squad cars surrounded a disused building, where police heard what they called "workshop noises."
The three men, hard at work on a Sunday afternoon, had been caught red-handed in the act of stealing metal.
When the price for raw materials is high, metal theft becomes a lucrative business. Cemetries are a favorite target. Last month over a hundred graves were defiled in the Aachen area in western Germany in just a few days.
The thieves made off with crosses and small figurines, and also chipped metal inscriptions out of headstones. A 600-kilo (1,320-pound) bronze statue was even taken from the Ohlsdorf cemetery in Hamburg.
Heavy metal detectors
But the criminals, often with professional equipment, don't just plunder graveyards, churches and memorials. Germany's huge rail network has also become a frequent target. Huge quantities of metal are incorporated into the network, which stretches over tens of thousands of kilometers.
German rail operator Deutsche Bahn reported as many as 1,500 cases of metal theft in the first four month of this year alone – a massive increase on 2009 when 1,800 cases were recorded over the whole year. A company spokesman estimated the losses from January to April 2011 at 10 million euros ($14 million).
Deutsche Bahn realized it needed to combat metal theft with some new, special measures. Since it's impossible to guard the entire rail network, the company has chosen to mark all non-ferrous heavy metals and cables with an "artificial DNA."
ID rail
The idea of marking valuable property indelibly is not new. Three hundred years ago, the British Navy invented a method of putting a red thread in its rope to mark it as military property. It worked. Stolen rope could no longer be sold safely, curbing the widespread epidemic of rope theft in British ports.
Deutsche Bahn now hopes to achieve the same effect by spraying its metal with a special alloy that can't be seen or felt. The alloy contains small "microdots" with a code that can only be read with a microscope. The code identifies the owner of the metal, potentially making it impossible to sell safely if stolen.
Deterrent
The "artificial DNA" is already being used in the northern city-state of Bremen, where small bottles of the alloy can even be bought over the counter. Customers simply bring identification and their data is then encoded into the micro-dots.
The clear liquid can be used to mark virtually any consumer products, including bicycles, stereo equipment, jewelry and mobile telephones. It acts as an effective deterrent for potential thieves and their middlemen, since the risk of being caught also depresses the price on the black market.
The liquid becomes visible under ultraviolet light, and the Bremen police are now equipped with the microscopes necessary to read the ID codes.
But it remains to be seen whether the technology will also work with Deutsche Bahn's metal. So far there is little experience of how well the liquid can withstand the extreme temperatures and weather conditions that the rail metal is exposed to all year round. It's also unclear whether the microdots will survive if the metal is melted down.
But for now Deutsche Bahn is banking on the liquid having a deterrent effect. Bremen police say they have already noticed a change – the number of burglaries has gone down in areas where signs have been put up to show that valuables are marked.
Author: Dirk Kaufmann / bk
Editor: John Blau