The Metropolitan Area of Buenos Aires is the third largest in Latin America, with millions commuters using public transport every day. As government officials we must make sense of the massive amounts of location data generated by our transport system. We used Apache Spark in combination with Geomesa in order to process over 100 million monthly GPS records from buses to create individual trajectories between terminals, infer direction of travel and derive meaningful performance indicators of transportation. We conclude that this is a great combination of tools to tackle big-geo and mobility problems of the kind expected in a big city government.