Public Interest Transportation Forum


Examination of monthly boardings on King County Metrobus and
Sound Transit Central Link Light Rail since light rail opened in Seattle

Data source: U.S DOT National Transit Database, Monthly Module Adjusted Data Release for October 2016

Charts created by John Niles, Public Interest Transportation Forum, December 8, 2016

King County Metrobus count sums up motor bus and trolley bus boardings. Sound Transit light rail boardings includes only Central Link and NOT Tacoma Link and NOT Seattle streetcars.

Chart 1: Raw count of monthly boardings July 2009 to October 2016 for King County Metro bus and Sound Transit light rail separately.  Monthly boardings data fluctuate considerably. The rapid rise of light rail ridership beginning March 2016 with the opening of two new light rail stations is clearly visible. Through October 2016, light rail boardings seem to have hit a plateau just below two million riders per month.  That many riders per month with Link’s historical annualizing factor of 332 means weekday ridership is settling down at approximately 2 million X 12 months divided by 332 equals 72,300 weekday boardings per month. This level still does not reach the earlier promise for 2010 of 105,000 per weekday made back in 1996 when the initial taxation authorization was achieved in a regional vote.  Sound Transit apologists will point out that the University District Station at NE 45 Street and Brooklyn is still not open to support high ridership promises.  Sound Transit critics would note that even with U District, Roosevelt, and Northgate stations opening in 2021, the agency has not forecast ridership exceeding 100,000 boardings per weekday until the mid 2020s.  Nevertheless, 73,300 daily weekday ridership is arguably close to the expectation set since 2007 for the two new stations of University Link plus the new station at Angle Lake.

Data source:

Chart 2: Five month moving average of monthly boardings for bus and light rail separately, to smooth out fluctuations and more clearly show the monthly boardings trend over time, November 2009-October 2016.  This technique muffles the effect of different numbers of non-holiday weekdays in a month.  Metro bus boardings trend was flat in 2010-2011 coming out of the recession, then grew, and now appears to be flat again with little growth since the summer of 2014 compared to 2011-2014.

Data source:

Chart 3: Five month moving average of monthly boardings for bus and light rail stacked on one chart to show combined total for both modes, November 2009-October 2016.  Boardings in these charts count vehicle boardings, and of course some light rail riders are riding a bus to get to the rail station. What was one boarding earlier is now a bus boarding PLUS a rail boarding for each trip by those who transfer in the morning from bus to rail, for a total of two boardings where there used to be just one.  Not surprisingly, combined bus and rail boardings have hit a new high in the most recent months on this chart.

Data source:  

Chart 4: Number of light rail boardings as a fraction of Metrobus boardings.  The fraction of light rail boardings has risen 2009 to 2016 from 3% to 18%.  In terms of sheer raw boarding numbers, Metrobus in 2016 remains five times more important for mobility in the Seattle region than Sound Transit light rail.

Data source:


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Last modified: December 15, 2016