  With the widespread installation of location-enabled devices on public
transportation, public vehicles are generating massive amounts of trajectory
data in real time. However, using these trajectory data for meaningful analysis
requires careful considerations in storing, managing, processing, and
visualizing the data. Using the location data of the Los Angeles Metro bus
system, along with publicly available bus schedule data, we conduct a data
processing and analyses study to measure the performance of the public
transportation system in Los Angeles utilizing a number of metrics including
travel-time reliability, on-time performance, bus bunching, and travel-time
estimation. We demonstrate the visualization of the data analysis results
through an interactive web-based application. The developed algorithms and
system provide powerful tools to detect issues and improve the efficiency of
public transportation systems.
