Ttraveltimes: Query travel times and travel time performance
In MBTAr: Access Data from the Massachusetts Bay Transit Authority (MBTA) Web API

Returns a list of travel times between an origin destination pair during a particular time period.

Ttraveltimes(from_stop_id, to_stop_id, route_id = NULL,
  from_datetime = (Sys.time() - 3600),
  to_datetime = Sys.time(),
  api_key)

`from_stop_id`	GTFS-compatible stop_id for the origin stop for which travel times should be returned.
`to_stop_id`	GTFS-compatible stop_id for the destination stop for which travel times should be returned.
`route_id`	GTFS-compatible route_id value for which travel times should be returned. If this is not included, travel times for all routes between the from and to stop will be provided.
`from_datetime`	The start of the time period that the travel time (arrival time at the destination stop) should fall within; converts to epoch time.
`to_datetime`	The end of the time period that the travel time (arrival time at the destination stop) should fall within; converts to epoch time.
`api_key`	API key for MBTA API. To obtain one, visit the MBTA Developer Portal (https://mbta.com/developers/mbta-performance)

`route_id`	Route ID for which travel time are returned.
`direction`	Direction id for which travel times are returned.
`dep_dt`	Actual departure times from origin stop during the time window specified.
`arr_dt`	Actual arrival times at destination stop during the time window specified.
`travel_time_sec`	Actual travel times for all trips during time window specified, in seconds.
`benchmark_travel_time_sec`	Benchmark travel times for each trip, in seconds. Benchmarks are based on median travel times during the last 30 days.