CHICAGO (CBS) — The CTA has launched its CTA Train Tracker website, allowing riders to use their computers and smart phones to view estimated arrival times for trains on all eight CTA rail lines.

Mayor Richard M. Daley and CTA officials announced the launch of the new website on Saturday at CTA headquarters in the West Loop.

The website provides estimated arrival times for trains at all 144 CTA train stations on all eight of the agency’s rail lines. CTA customers can visit and follow the link on the page to CTA Train Tracker. There is also a mobile version of the program for smart phones.

Customers select their rail line and then choose the station from which they will board the train. Arrival times of approaching trains are provided within a 15-minute timeframe for the selected station — with results refreshing approximately every 20-30 seconds, according to a news release.

“The innovative use of this technology will improve CTA reliability and make traveling around Chicago more pleasant and convenient for our residents,” Daley said in a written statement on Saturday.

Also, at several stations, electronic signs will announce when CTA trains will arrive, both at mezzanine levels and on platforms.

The CTA concedes the Train Tracker system will not be quite as accurate as the popular Bus Tracker system. The Bus Tracker uses GPS technology, but the Train Tracker will gather its information from signaling systems and sensors on the tracks.

Some CTA stops already have electronic arrival time signs, but they are not uniform in age, size or character availability. The 47th Street, Sox-35th, and Addison Red Line stops, the Davis Purple Line stop, the Roosevelt Green-Orange Line stop, and the 18th Street Pink Line stop all feature a full-color digital display. But the Belmont Red-Brown-Purple line station, among several others, uses yellow LED-light sign.

Thus, the CTA has been seeking a consistent method of delivering arrival time data.

Estimated arrival times are generated through a combination of scheduling information and data collected by the software that monitors the signal system to indicate when a portion of track is occupied by a train.

CTA Train Tracker calculates estimated arrival times by first measuring how long it takes a train to travel a portion of track and then averaging the times of the last five trains to move across a portion of track.

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