Officials with San Francisco International Airport (SFO) have announced a pilot program to test the usefulness of sensors placed on the walls to help blind people find their way. The sensors will emit Bluetooth signals for capture by smartphones running an associated app. The signals will be converted to voice messages telling the user which way to turn to get to their destination, similar to that used for drivers using GPS systems.

GPS, by all accounts, is a major hit, especially for helping drivers get to where they want to go—but it doesn't work indoors, which has led to some work-arounds. Some hardware makers have been betting on near field communications, others are going with the more established Bluetooth. That's the case with Austrian indoor positioning company, Indoo.rs—they're the ones that make the going on the walls of Terminal 2 at SFO. The sensors are round and black, slightly larger than a quarter, and rely on battery power—each costs $20 and is projected to last for four years before running out of juice. They emit Bluetooth signals which are translated to location information on a smartphone.

As a person walks, they are transferred between sensors in a way similar to the way drivers using cell phones are passed from tower to tower automatically. That allows for not only offering directions, but for dishing out other useful information, such as calling out the names of restaurants or noting bathrooms as a person walks towards their ultimate destination. SFO and Indoo.rs have another partner as well, Lighthouse for the Blind, an organization with a history of providing services to those with vision impairments. If the program is successful, SFO plans to expand the sensors to the entire airport, providing assistance from curbside to boarding gates.

Workers have installed 300 of the sensors which are already being put to the test by technicians, and presumably volunteers—if all goes well, the app will be made available for public use in just a few months time. Indoo.rs has suggested that non sight-impaired people may also want to use the app to help them find their way around the airport.