Public Interest Transportation Forum -

Measuring Sound Transit Link Light Rail Reliability

About one quarter of a sample of light rail trips took three minutes or more longer than the schedule showed.

The below field observations were made on a random sample of 23 trips on Link Light Rail from September 4 to October 9, 2009, between Westlake and either Tukwila or Rainier Beach, both directions. No trips taken by the observer were excluded from the sample.

The scheduled travel time for these trips is 34 minutes in the case of Tukwila and 25 minutes for Rainier Beach.

Results of the survey:

 The observed and measured trip time was no more than one minute slower than scheduled 35% of the time, 8 trips, indicated in the green rows below.

39% of the trips, the light rail travel time was one to two minutes longer than scheduled -- 9 trips, indicated in yellow rows.

13% of the trips, travel time was three to four minutes longer than scheduled -- 3 trips, shown in orange rows.

And in another 13% of the trips, travel time was six to 23 minutes longer than scheduled -- 3 trips, shown in red below.

Date Day of week Departure time Departure Arrival Actual trip time Scheduled Time Lateness
17-Sep THU 11:20 AM Rainier Beach Westlake 23:00 25:00 Faster
23-Sep WED 12:50 PM Tukwila Westlake 32:55 34:00 Faster
17-Sep THU 10:55 AM Westlake Rainier Beach 25:00 25:00 0:00
9-Oct FRI 6:35 AM Westlake Tukwila 34:00 34:00 0:00
30-Sep WED 4:51 PM Westlake Rainier Beach 25:15 25:00 0:15
4-Sep FRI 9:00 PM Tukwila Westlake 34:35 34:00 0:35
8-Oct THU 2:43 PM Rainier Beach Westlake 25:40 25:00 0:40
4-Sep FRI 8:14 PM Westlake Tukwila 34:45 34:00 0:45
9-Oct FRI 8:27 AM Westlake Rainier Beach 26:20 25:00 1:20
23-Sep WED 12:06 PM Westlake Tukwila 35:25 34:00 1:25
30-Sep WED 4:21 PM Rainier Beach Westlake 26:30 25:00 1:30
2-Oct FRI 10:35 AM Westlake Rainier Beach 26:30 25:00 1:30
14-Sep MON 3:30 PM Westlake Rainier Beach 26:35 25:00 1:35
30-Sep WED 3:50 PM Westlake Rainier Beach 26:40 25:00 1:40
8-Oct THU 3:49 PM Rainier Beach Westlake 26:45 25:00 1:45
14-Sep MON 4:40 PM Westlake Rainier Beach 27:00 25:00 2:00
17-Sep THU 11:45 AM Westlake Rainier Beach 27:00 25:00 2:00
8-Oct THU 2:15 PM Westlake Rainier Beach 28:00 25:00 3:00
8-Oct THU 3:11 PM Westlake Rainier Beach 28:30 25:00 3:30
14-Sep MON 4:00 PM Rainier Beach Westlake 29:00 25:00 4:00
9-Oct FRI 8:54 AM Rainier Beach Westlake 31:05 25:00 6:05
9-Oct FRI 7:35 AM Tukwila Westlake 43:30 34:00 9:30
2-Oct FRI 11:09 AM Rainier Beach Westlake 48:00 25:00 23:00

Notes from the observer on the three longest delays in the red columns:

9-Oct 8:54 am:  Everyone on my train forced to get off at Mt. Baker Station, because it went out of service. All passengers boarded a following train, and the arrival time is for this second substitute train.

9-Oct 7:35 am: The train ahead of this one broke down, and all those passengers had to board my train at Stadium station.  Passengers on the broken down train experienced a longer delay than I reported for my train.

2-Oct 11:09 am: The train ahead of this one broke down, and all those passengers had to board my train at SODO station.  Passengers on the broken train experienced a longer delay than occurred on mine.

Click here for complete information from Sound Transit on riding Central Link Light Rail. The seated capacity of the trains is far from being used during most hours of the day, so now -- in the early days of operation -- is a good time to experience light rail.

There is nearly always available free parking at the Tukwila Station just north of SeaTac Airport on International Boulevard (SR 99); otherwise, the easiest access is via Metro Bus to downtown Seattle's Transit Tunnel, where your paper bus transfer lets you take a round trip on Link for no additional fare through the end of the year.

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Last modified: February 07, 2011