def GetFrequencyStartTimes(self):
    start_times = []
    for freq_tuple in self.GetFrequencyTuples():
      (start_secs, end_secs, headway_secs) = freq_tuple[0:3]
      run_secs = start_secs
      while run_secs < end_secs:
        start_times.append(run_secs)
        run_secs += headway_secs
    return start_times