Arrival Times

The Chicago Transit Authority is opening up its transit arrival data to web developers, spurring what officials and riders hope will be the creation of new tools to make riding transit in the city easier.

Some transit agencies keep it under wraps, while others share it widely. Three cities in the U.S. show how the availability of transit arrival data is a wild frontier.

Philadelphia's public transit system is preparing to launch a new service that makes bus and train arrival times available to riders' handheld devices.