The proportion of commuters in each direction matters as well. For instance, if we have two equivalent lines, each with the same ridership, and 90% of Line A’s AM peak trips are inbound while only 60% of Line B’s are, Line A will be more congested. It would still be more congested even if Line B had 10% more riders.
Another factor that must be considered is the spreading of trips along the line. Not every rider starts at a suburban terminal and rides to downtown. Some start at suburban terminals and ride to suburban office centers, while others start in urban neighborhoods and ride into or through downtown. The Red Line is the longest line and has more stations than the Orange Line, so more riders are to be expected.
Finally, the amount of rail service impacts congestion. The Red Line does not share trackage with any other rail line. This means that the number of trains per hour is higher on the Red Line than it is on the Orange Line, which shares tracks with the Blue Line.
With these factors in mind, let’s look at rider volumes. The link with the most riders in the system, according to my analysis, is the inbound Blue/Orange shared segment between Rosslyn and Foggy Bottom, which carries 44,719 people between opening and 9:30 AM. In second place is the next link inbound, from Foggy Bottom to Farragut West, carrying 41,137 riders during that period. In third place comes the Red Line, with 31,773 trips from Dupont Circle to Farragut North. This means that the most used section of track of the Red Line carries only 70% as many riders as the busiest section of track on the Blue and Orange Lines.
But the real crux of the issue becomes clear at the Rosslyn junction point. At Rosslyn, 65% of inbound riders are on the Orange Line, but only 60% of trains are on the Orange Line. That means that passenger demand slightly outstrips the supply of railcars at that point. And the inbound track between Court House and Rosslyn is the 7th busiest in the system during the AM Peak.
|OR||BL||Foggy Bottom||Farragut West||41,137|
|RD||Dupont Circle||Farragut North||31,773|
|OR||BL||Farragut West||McPherson Sq||31,448|
|RD||Woodley Park||Dupont Circle||31,156|
|RD||Gallery Place||Metro Center||31,002|
|RD||Union Station||Judiciary Sq||30,694|
|RD||Cleveland Park||Woodley Park||29,143|
|RD||Judiciary Sq||Gallery Place||28,685|
|RD||Van Ness||Cleveland Park||27,163|
|OR||BL||McPherson Sq||Metro Center||26,264|
|OR||BL||Eastern Market||Capitol South||25,944|
|OR||BL||Capitol South||Federal Center SW||25,855|
|OR||BL||Metro Center||McPherson Sq||25,422|
With the most riders, the Red Line certainly faces crowding issues, although the crowding might not be as acute as it is on other lines due to ridership patterns.
The Red Line essentially operates as two overlapping services during rush hours. One service runs the full length of the line, from Shady Grove to Glenmont and back. The other service only runs between Grosvenor and Silver Spring.
At the Shady Grove end of the line, trip volumes on the link between Shady Grove and Rockville (in that direction) are just under one-third of the volume of the highest Glenmont-bound link, between Dupont Circle and Farragut North. The Shady Grove-Rockville link’s volume is roughly half of the Grosvenor-Medical Center link. That link is just over 60% of the Dupont-Farragut link. Ridership increases by about one-quarter from the White Flint-Grosvenor link to the Grosvenor-Medical Center link.
On the other side of the Red Line, trains leaving Glenmont for Shady Grove travel on a link whose volume is about 14% of those of the most heavily-traveled link, the one between Gallery Place and Metro Center. The Glenmont-Wheaton link is about one-third the volume of the Silver Spring-Takoma link. Ridership increases by over 70% between the Forest Glen-Silver Spring link and the Silver Spring-Takoma link. Based on these numbers, the case for Silver Spring short-turns is fairly clear cut – almost twice as many inbound trips are made south of Silver Spring as they are on the busiest inbound link between Glenmont and Silver Spring.
Analysis of the other lines is not as easy since they share track with other colors downtown and in Alexandria. I’ll let you compare links for yourself below.
Note: combined line segments reflect the total ridership on that segment, not just the riders on a particular color train. For example, link C2, track 1 carries 31,448 riders overall during the AM Peak on both the Blue and Orange Lines, not each individually.
Note: All figures referenced in this post refer only to the AM Peak period (opening-9:30AM).