Frequencies¶
Describe a frequency-based service¶
The Société de Transport de Montréal operates transit services in Montréal and runs a frequency-based service for its metro lines. Hence, instead of providing a schedule with arrival and departure times in a GTFS dataset, the file frequencies.txt is used to describe the service frequency throughout the span of the service. Having a trip repeat only works in cases where the timing between stops remains consistent for all stops. When modeling a Frequency-based service, stop_times.txt (@TODO link) contains the relative times between stops in order to determine the times to be displayed to riders.
trip_id,start_time,end_time,headway_secs
22M-GLOBAUX-00-S_1_2,16:01:25,16:19:25,180
22M-GLOBAUX-00-S_1_2,16:19:25,17:03:25,165
Above, a trip on the Green line with a trip_id=22M-GLOBAUX-00-S_1_2 is used as an example. For that trip, the first record indicates that between 4:01:25 PM and 4:19:25 PM, trains run every 180 seconds (or 3 minutes). Similarly, the second record indicates that between 4:19:25 PM and 5:03:25 PM, trains run every 165 seconds.