Media Hype and Not the Numbers are Delaying the Purple Line

In a surprise ruling last month, Judge Richard Leon found that backers of the Purple Line planned for suburban Maryland failed to adequately consider the impact on its ridership from recent issues with Washington’s Metrorail system. This ruling has big implications because if it withstands an appeal it would force Maryland to reissue its environmental document threatening both its federal funding and the bids from its public-private partnership procurement. The plan was to have the same team both build the line and maintain it for 36 years but that may be in jeopardy. Unfortunately, the ruling is simply not supported by the numbers and even if Maryland had evaluated this in more detail, their only conclusion would have been that there is no significant impact that could be expected.


The Purple Line is a planned 16-mile light rail line that would act as part of a circumferential line connecting areas in suburban Maryland to the rest of the Washington DC Metro system. The route runs from the New Carrolton station in the east (Orange Line), connects to the College Park station (Green Line) and Silver Spring (Red Line) in the middle, and ends at the Bethesda station (Red Line) in the west. With all of these connection, the environmental study that Maryland completed found that about one-quarter of riders on the Purple Line would use the Washington Metro to get to/from the line.

The judge’s ruling hinges on the claim that Maryland did not adequately evaluate the impact on ridership of the Metrorail system’s recent safety and ridership woes, which have been well-documented (see here, here, here, and here as examples). As you can see in the chart below from the Washington Post, ridership has declined from a peak of over 750,000 daily riders in 2009 to 713,000 in 2015. This represents a 5 percent drop in ridership and a slightly higher drop in ridership per capita when taking into account recent population growth in the region.


In its environmental document, Maryland simply said that they do not run the Metrorail system so this is not their issue to study. The judge found this inadequate and referred to it as “cavalier” in his ruling. However, where the judge’s argument falls apart is that if Maryland had actually studied this question in more detail, the only conclusion they could have reached is that the recent woes will not have a significant impact on the forecasts.

I don’t have the breakdown of the ridership declines by different trip origins/destinations but I think it’s fairly safe to assume that the issues have been so widespread that the declines are roughly evenly distributed and that suburban Maryland is not the hotbed of non-riders. If we take that assumption then we need to consider two things:

  1. How much has ridership declined so far?
  2. How much more will it decline before it stabilizes/starts growing again?

As we know, so far the drop has been about 5% since 2008 (over the span of 7 years). With the forecasts being made out to 2040, let’s assume that there are 7 more years of a similar decline resulting in a total drop of 10% of the riders. This seems like a pretty significant downside scenario and I would expect things to be better than this. But even this downside scenario, assuming it applies equally to the Purple Line access trips, results only in around a 2.5% drop in ridership. If no further declines are assumed then this would be just over 1.3% of ridership.

So basically the judge found that because of a potential overestimate of either 1.3% or maybe 2.5% in a downside scenario, the project should be delayed for 6 months costing potentially millions of dollars in delay claims. Without even looking at the ridership studies in depth, I can guarantee that there are at least a half-dozen other assumptions in there that could have a larger downside than 1.3% – 2.5%, they just haven’t been in the headlines. Unfortunately, the judge bought into the media hype instead of looking at what the numbers actually tell him.


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