The Chicago Transit Authority (CTA) will launch a pilot version of the highly anticipated CTA Train Tracker in early January via a dedicated website. Customers using desktop computers or mobile Web-enabled devices, such as iPhones, BlackBerries or smartphones, will be able to access estimated arrival times for trains on all eight rail lines.

Estimated arrival times will be generated through a combination of scheduling information and data collected by the CTA's QuickTrak program, which monitors signaling systems and indicates when a portion of track is occupied by a train.

An average transit time is determined by measuring how long it takes a train to travel a portion of track. By averaging the travel times of the last five trains to move across a portion of track, the CTA can calculate the estimated arrival times for trains at each station.

To view estimated arrival times, customers will simply have to go to the dedicated website, select their preferred rail line and then choose a station. Arrival times of approaching trains within a 15-minute timeframe will be provided for the selected station, and results will refresh approximately every 20 seconds to 30 seconds.

Customers will have the option to choose the number of results displayed and how they are sorted — either by track or route if the station is served by multiple rail lines; or by time to arrival.

In the event arrival times cannot be calculated — such as with the first trains in the morning — Train Tracker will provide and indicate schedule information for the next arriving train(s).

Since April, stations equipped with electronic signs have been testing estimated arrival time displays. Because the electronic displays across the rail system are not uniform in age, size, character availability or the number of lines displayed, personnel have been working diligently to develop a consistent method of delivering accurate data for the various display types.

As part of the Train Tracker pilot, electronic signs at 10 CTA stations also will feature arrival information either on the platform or mezzanine levels.

Specific details regarding CTA Train Tracker and station locations that will display train arrival information will be made available in January when the program is officially launched, according to the agency.