Many cities in the world have incorporated information technology to their public transport systems, and continue advancing along these lines. Santiago, Chile is not an exception, and the new public transport system Transantiago has introduced GPS bus location and smartcard payment systems. However, this particular case has some characteristics that make it particularly interesting for passive data collection: most payments are made by smartcard, therefore a very high percentage of boarding transactions are recorded in a huge Transactions database and all buses are equipped with GPS device that generates an even bigger Positions database. These characteristics, which are not yet present in other transport systems, will most likely be the standard in the future. This represents an excellent opportunity for public transport planners, as cards (users) can be followed through the system to identify their travel patterns. This source of information has so much space-time detail that once processed would permit analyzing not only mean attributes at any desired level of time-space disaggregation, but also variance and regularity of behaviour. This paper describes the data and some of the potential applications, and shows some preliminary results. A method is proposed to estimate boarding and alighting bus stops, and to estimate travel time and time assigned to activities between trips. The method is applied to a sample of the database. Some preliminary results and the success rates are shown.