Service Reliability
The MBTA performance dashboards are undergoing service maintenance. During this time, the dashboards may be unavailable. We apologize for the inconvenience and thank you for your patience.
We can’t improve service reliability without first accurately measuring it. To measure how reliable our service is for riders, we use different metrics for each mode. We use different metrics for each because they don't operate the same. These metrics also reflect how riders experience them.
How We Measure Service Reliability
Subway: Wait Time Between Trains
To determine subway reliability, we measure the percentage of riders who waited less than or equal to the amount of time scheduled between trains.
We use wait time as our subway metric since service runs frequently throughout the day. Riders do not need to rely on printed schedules.
Commuter Rail: Arrival Time at Final Stop
We determine Commuter Rail reliability by measuring the percentage of trains that arrive at their final stop no more than five minutes late.
We use this metric since Commuter Rail follows an infrequent schedule with specific times that riders plan around.
Bus: Departure Time for Frequent and Infrequent Routes
Bus reliability depends on how frequently buses run on a particular route.
Frequent routes have buses that come every 15 minutes or less. We measure their reliability by calculating the percentage of buses that depart no more than three minutes late.
Infrequent routes have buses that come more than 15 minutes apart. We measure their reliability by calculating the percentage of buses that depart no more than one minute early and no more than six minutes late.
The RIDE: Scheduled Pickup Time
To determine reliability for The RIDE, we measure the percentage of completed trips where riders were picked up 15 minutes or less after their scheduled pickup time.
Currently, data for The RIDE is not in the dashboard. We're still working on accurately displaying that data. Check back here for updates.
How We Measure Subway Trip Time
Trip time is how many minutes it takes for a rider to travel from one end of a subway line to the other. Each line travels in two directions and has separate trip times for each direction.
To calculate trip time, first we find the daily median trip time for each direction on the Orange, Red, and Blue lines. Then, we calculate the average of both medians from each of those lines to find each line’s daily average trip time. Finally, we calculate a seven-day average trip time for each line, each day. To do that, we find the average of the seven most recent daily average trip times.
Trip time data for the Green Line and Mattapan Line are not currently included in the dashboard. We are in the process of upgrading the way we collect data for those lines so we can provide thorough information in the future.
