Transit and tech leaders want to reward mobile app developers with $50,000 for making the MTA system useful for everyone, including those who can't see and other disabled riders.

The Metropolitan Transportation Authority and AT&T Wednesday launched the third annual App Quest, which promises the prize money supplied by AT&T, for developers of transportation-related apps.

This year, organizers are urging developers to focus their efforts on disabled riders, including by taking advantage of new technology being tested in Grand Central Terminal that can pinpoint the exact location of a mobile user "down to the foot," according to MTA chairman Thomas Prendergast.

The "PROMObeacon" technology could be used to help visually impaired customers navigate the subways, officials said.

"I have to listen to when the trains are coming . . . I have to be careful with the gaps when traveling, and where not to exit," said Matt Puvogel, a visually impaired representative from the Mayor's Office for People with Disabilities, at the Manhattan news conference announcing the contest. "Apps and other technology . . . can help with these situations, creating less stress for the traveler."

For about four years, the MTA has made internal data, including train and bus arrival times and service disruptions information, available to private developers to come up with their own third-party apps. Prendergast said Wednesday he was "proud of what we've done to open ourselves up to the world."

Among new data at developers' disposal is real-time information on the exact location and train arrival time of a Long Island Rail Road or Metro-North train, using global positioning systems and other train-monitoring technology. The LIRR is already using the data in its official app, LIRR Train Time.

"The ability to now have this data available opens a whole new world to us on the Island, and we're very excited," said AT&T New York President Marissa Shorenstein, adding the apps will be judged on their creativity and viability.

Last year's grand-prize winner, Citymapper, which gives real-time travel information across various transportation modes for several metropolitan areas, has been downloaded about 1.8 million times.

"Our goal is to continue working with app developers to make the best apps possible for our customers," Prendergast said.

More information on the contest is available at mtaappquest.com.