By Ian Bush

PHILADELPHIA (CBS) — If you’ve driven through the tunnels in Baltimore or New York City, you probably know the frustration of riding blind: no GPS signal means no directions upon emerging into daylight. That can cause a missed exit — or worse. Now, there’s a solution. It comes from a popular navigation app.

Waze has come up with electronic beacons, each about the size of an E-ZPass, installed within tunnels to guide the way via Bluetooth.

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“This is going to help Wazers never miss that in-tunnel exit again,” said spokeswoman Meghan Kelleher, “and will reduce those in-tunnel collisions caused by last-minute lane changes.”

Kelleher says one beacon is placed every 40 feet or so to provide seamless smartphone navigation throughout the tube and to allow people to note traffic troubles on the crowdsourcing app. But even non-Waze users can benefit.

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“It’s actually an open technology,” she said. “We’re making it available free of charge to other navigation services.”

Each mile of beacons costs about $300 per year. The hardware is made by Bluvision with batteries are designed to last about six years.

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Waze has just switched them on in the Fort Pitt and Liberty tunnels in Pittsburgh with an eye on getting governments and other agencies to foot the bill in the rest of the world’s tunnels.