Overlapping schedules for buses?

[Juan]

Hi MTA folks,

We've noticed that it seems possible to determine the 'blocks' that MTA buses run on via the trip_id field in trips.txt.

For example, tripId MV_D2-Saturday-056400_M3_314 seems to belong to block M3_314.

If we look for block M3_314 elsewhere in the trips.txt file, we find other trips for that service_id that are chronologically ordered.

Given tripId (MV_D2-Saturday-056400_M3_314), if we look at the next trip (MV_D2-Saturday-065400_M3_314) in the series, we notice the arrival time to the last stop of the first trip is 11:02 and the departure time of the first stop of the second trip is 10:54. These times overlap by 8 minutes and assume no layover.

The situation is the same for many other trips. Though the spec does not define a relationship between the trips, guessing how the system behind this data could be working and indexing the data, it looks suspicious. 

We've also noticed that the trip times for subway runs seem to be similarly padded towards the end of the trips.

Is there any more information you could give us regarding this?

Thanks in advance.