Predicting people's mode of transportation is quite a complex yet challenging study. It involves vast amounts of factors, of which those are reflecting the way people behave and choose their everyday travel mode. In big cities, people are encouraged to take public transportation provided by the government to unravel the congestion. Nevertheless in Jakarta, the intention to use public transportation remains low. The cause is that the public transportation still provides low service standards, far below the expectation and needs. This preliminary study was intended to enhance the public transport improvement planning. With regard to this intention, demographic data of Transjakarta passenger and non-passenger were collected through a survey. Decision trees were utilized to predict travel mode switching. The result of this study is that 60.8% of Transjakarta passengers and 57.1% of private vehicle users tend to consider switching their current transport mode. Transjakarta must be continuously improved, especially on the public's complaints about safety, heading way, people's comfort in the queue line, quality of the road in busway corridor, and non-sterile bus lane. The alternative of the new transportation mode will definitely change the travel mode choice behavior of Jakarta Greater Area people. This will be a challenge in future travel mode switching prediction research.