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In the last decade, 23 workers have died fixing railroad tracks in the U.K., where the gap between lines can be just 4 to 6 feet. Tended’s high-precision wearable device, which uses similar technology to drone-positioning systems, can pinpoint a wearer’s location to around half an inch, raising an alarm if they stray too close to a live track. (GPS, by comparison, can locate a person’s position to within 16 feet.) Funded by the European Space Agency, the geofencing technology is already used by the UK’s National Rail. “We just build really cool s–t,” says Tended CEO Leo Scott Smith, “and hope that one day it will save somebody’s life.”

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