Directional rider flows on Metro
In July, I analyzed how people travel within the Metro system, using a survey to estimate riders' choice of alternate routes.
Because the data used was for average daily travel between origin and destination stations, it was not possible to determine which stations were primarily 'commute from' stations and which were primarily 'commute to' stations. However, after my July post, WMATA offered to give me time-specific data, which allows us to look at commuting patterns. The data used for this revised analysis looks at trips taking place between system opening and 9:30AM. The dataset comes from an averaging of AM Peaks from early May 2009.
The methodology used to assign trips to each link in the system is the same used for the initial model and analysis, published in July. In the above graphic, each segment of the Metro line comprises two lines. One line represents inbound trips, the other represents outbound. The thickness of each line represents the total volume on any given segment.
From the graphic it is clear that, not surprisingly, most AM peak trips on Metro are inbound. Most of the reverse commuting in the region seems to occur on the Shady Grove branch of the Red Line, the Vienna end of the Orange Line, and the common Blue and Yellow Line segment in Arlington and Alexandria.
This analysis also gives us a good estimate of the proportion of passengers traveling on different lines at the junction points. For instance, at Rosslyn, 65% of inbound passengers entering the station do so on the Orange Line, while 35% come in on the Blue Line. Outbound trips are slightly more balanced, with 60% on the Orange Line and 40% on the Blue Line.
In addition to measuring volume on each line segment, this analysis allows us to consider each station based on how "busy" it is. Metro's faregates keep a record of the number of entries and exits at each station, but they are unable to determine where people transfer. As a result, stations like Metro Center and L'Enfant Plaza appear less busy (on paper) because the people transferring there are not counted. Below is a list showing Metro stations ranked on their level of traffic.
Note that the "transfers" column does not count passengers who don't change platforms. This is because for someone changing to a train on the same track with multiple common stations, it is not clear where they transfer. Transfers in the table below only refer to passengers who change platforms, from the outbound Blue to the inbound Yellow at Pentagon, for instance.
|18||West Falls Church||6,894||1,390||-||8,284|
|39||Federal Center SW||475||4,214||-||4,690|
|47||Largo Town Center||3,552||410||-||3,962|
|48||Rhode Island Ave||2,652||1,197||-||3,848|
|56||New York Ave||1,087||2,023||-||3,109|
|59||East Falls Church||2,639||256||-||2,895|
|62||Prince George's Plaza||2,089||728||-||2,817|
|65||Van Dorn Street||2,437||300||-||2,737|
|69||Mt. Vernon Sq||1,164||1,106||-||2,270|
Looking at the 'exits' field reveals some interesting attributes. This field can be considered a reasonable proxy for office access. The first station in exits outside of downtown Washington is Arlington's Rosslyn station at #12. Medical Center is Montgomery County's leading station for exits at #21 and is followed by #22, King Street as the highest in Alexandria. Fairfax's most exited station in the AM Peak is West Falls Church at #33. Prince George's County's New Carrollton comes in at #42. In the case of West Falls Church, it is likely that many of the exits are passengers transferring to buses headed for Tysons or Reston.
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