Bus headway grades are calculated from the headway adherence percentage. This percentage reflects how many visits to bus stops occurred no more than 3 minutes after WMATA's official scheduled time window with respect to the previous bus's visit to that same stop.1 The scheduled headways come directly from WMATA and change based on day, time, and route.
A headway adherence grade of A+ would require 97% or more of all bus arrivals to occur no more than 3 minutes outside of their scheduled spacing window.
Bus schedule grades are calculated from the schedule adherence percentage. This percentage reflects how many visits to bus stops occurred no more than 2 minutes earlier or 7 minutes later than the scheduled clock time for that bus's arrival.1 The scheduled times come directly from WMATA and change from day to day.
A schedule adherence grade of A+ would require 97% or more of all bus arrivals to occur within this 9 minute window of their scheduled clock time.
Bus speed grades are calculated by comparing the average speed (in mph) of all observed bus trips to the goal speed of 11 mph.
A speed grade of A+ would require all observed bus speeds to average out to 11.44 mph or faster. (Because an average speed of exactly 11 mph meets, but does not exceed, our minimum goal, this has been scaled to equate to a 93%: the minimum score necessary to receive an A.) Bus speeds higher than 11.77 mph cap out at 100% to ensure that they do not unfairly weight the main grade.