@classmethod
def is_arrival(cls, session, trip_id, stop_id):
    """
        :return True if it looks like this Trip / Stop pair is an arrival only
        NOTE: this routine might be EXPENSIVE since it is
        Further, this routine isn't well thought out...not sure block.is_arrival() works
        """
    _is_arrival = False
    from gtfsdb import Block
    blocks = Block.blocks_by_trip_stop(session, trip_id, stop_id)
    if blocks:
        for b in blocks:
            if b.is_arrival():
                _is_arrival = True
                break
    return _is_arrival
