If you hear one car horn blaring, it's probably a slow driver.
If you hear dozens at once, killer squid could be on the loose! Or a volcano may have appeared just down the road.
Scientists at the INT in Germany have come up with a patent for technology that will sound the horn of every parked car in a city during a disaster.
Safety from satellites
The technology is based on the EU eCall emergency system, which new cars are going to be equipped with as from September next year. It consists of a GPS sensor and a mobile phone component that's activated only in case of an accident to transmit the time, coordinates and direction of the vehicle to an emergency call centre.
The INT researchers think that this technology can also be used to warn the population about marauding wildebeest and hailstorms of frogs. Once the cars are equipped with a radio receiver, their horns can be triggered by civil protection agencies in case of disaster.
Guido Huppertz from the INT's Technology Analyses and Forecasts department explains the advantages of honking cars: "Previously solutions such as mobile phones or smoke detectors only inform a single user. The entire population can only be alerted if everyone has these devices. However, a mere 14 per cent of vehicles on the road are sufficient to provide extensive alarming."
If all new vehicles are equipped with eCall from the end of next year, the warning system may be ready for use in just two to four years, Huppertz predicts.
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Mark Harris is Senior Research Director at Gartner.