MBTA installing underground tracking system for Green Line trolleys

By Steve Annear GLOBE STAFF

Riders of the MBTA's Green Line will soon be able to pinpoint the locations of underground trolleys in real-time and get accurate arrival information on their smartphones.

MBTA officials said Tuesday that special tracking technology has been installed from Lechmere to Haymarket Station. Additional equipment will be installed at the Kenmore, Hynes, Copley, Arlington, and Prudential stations over the next few weeks.

The MBTA will start to release some location data to track the trolleys as soon as next month.

The tracking devices, known as Automatic Vehicle Identifiers, or AVIs, will allow passengers to use third-party apps <http://www.bostonglobe.com/metro/2014/10/24/here-how-track-your-next-green-line-train/jc2cHzUVMYmyIrottE5rbI/story.html> to follow the location of underground trains.

The Green Line project began in October of last year when the MBTA installed GPS devices <http://www.bostonglobe.com/metro/2014/10/23/real-time-tracking-comes-green-line/PAPXoxeYosY4zJB1cxIRyK/story.html> on all of its trolleys.

Because the same GPS technology doesn't work underground, the T has to retrofit the tunnels with the special AVI track sensors along those portions of the Green Line routes.

The Park Street, Boylston, and Symphony stops will be next in line, according to the transit agency.

"Once hardware is installed, location data will be released, followed by predictions being displayed on message boards," said T spokesman Joe Pesaturo.

Pesaturo said the entire installation process will be completed within four months, but the bulk of the work is underway.

The entire project is being funded through a $13.4 million grant from MassDOT, according to Pesaturo.

The transit agency already offers real-time tracking and countdown clocks for all of its rapid transit lines and commuter rail trains.