OpenTripPlanner up to 2× Faster: RAPTOR Route Optimization for Transit Agencies

Route optimization for transit agencies runs, more often than not, on OpenTripPlanner (OTP), one of the world’s most widely used open-source multimodal journey planners. It combines transit schedules with walking, cycling and ridesharing, and its users range from single city agencies to national governments.

It powers trip planning for TriMet (Portland), MBTA (Boston), MARTA (Atlanta), LA Metro, Sound Transit (Seattle), HART (Tampa), METRO (Houston) and New York State DOT in the United States, and for nationwide deployments in Norway and Finland, Skånetrafiken in southern Sweden, Rennes and Grenoble in France, Piemonte/Torino and Trento in Italy, Lower Saxony and Leipzig in Germany, and Valencia in Spain.

RAPTOR (Round-Based Public Transit Routing) is an algorithm for finding journeys in public transport networks. It works in rounds directly on the timetable, without building a graph first: the first round finds every stop reachable on a single ride, and each further round allows one more transfer. OpenTripPlanner 2 uses RAPTOR for its transit search.

We profiled the hot paths of the routing core and targeted the highest-impact bottleneck. The fix is a few lines of code — sorting a list and adding a single early-exit test — which kept the change low-risk and easy to upstream.

The full technical write-up, with benchmarks across networks, is in our research article.