Typically, at controlled railway crossings, hard-wired sensors are used to detect when trains are coming. This means that electrical and communications wiring has to be laid from them to the crossing itself, activating the lights and lowering the gates. Now, however, researchers at Britain's University of Huddersfield are creating tiny wireless sensors that are powered by vibrations in the rails themselves.

Numerous sensors would be used at each location, communicating with one another to form a network going down the track toward the crossing. Attached to the rails, each sensor would harvest energy from vibrations made by approaching trains, and would use that to transmit a signal down the line. If any one of the sensors were to malfunction, the network would simply reroute the warning signal around it.

According to the university, such a system could be installed for less than £20,000 (about US$26,000) per crossing. By contrast, installation of conventional detection systems can run as high as £500,000. Additionally, the wireless sensors could be used not only to detect trains, but to monitor the condition of the tracks.

Perhaps not surprisingly, the Huddersfield team isn't the first to conceive of such technology.

Researchers at the University of Nebraska-Lincoln are working on several concepts, while a team from Stony Brook University has developed a working prototype device.