Is Your City Making Full Use of Existing Transit Investments?

In Chicago, fewer people are living near transit, even though rising rents say demand is high. Graph: Metropolitan Council
In Chicago, fewer people are living near transit, though rising rents indicate demand is high. Graph: Metropolitan Council

Chicago’s rail transit infrastructure has a lot of unused capacity, Yonah Freemark wrote last week on the blog of the Metropolitan Planning Council, and making use of it might be cheaper and easier than expanding the system.

Some of Chicago’s most transit-accessible neighborhoods are barely growing, but rents are rising fast, Freemark reported, an indication that additional transit-oriented housing could be supported. Unfortunately, zoning laws limit new construction in these areas, says Freemark, so countless would-be transit riders move to the suburbs or other regions, outside the reach of transit service.

Inspired by that article, David Levinson at looked at how much additional capacity there is on Minneapolis’s new Green Line — one of the biggest transit success stories of last year — which carries about 38,000 riders daily. Depending on how you calculate capacity, there’s actually quite a bit to work with, says Levinson.

This measures capacity in terms of daily boardings. Daily miles traveled is another measure, and is independent of the length of trips. To calculate this we use the following equation:

Capacity = (Hours of Operation)*(Trains/Hour)*(Cars/Train)*(Capacity/Car)*(Stations – 1) * (Trip Length) * (Directions Operating).

At any rate, the attached table shows some surprisingly high numbers, up to 7 million (under the admittedly silly unconstrained scenario (A) where people only ride the train for 1 stop before alighting, trains run for 24 hours a day, and people are standing at near crush capacity), with more plausible numbers in the 255k territory, assuming everyone gets a seat, but you can run at 5 minute headways (C). Here we are limited by capacity in one section (downtown Minneapolis), which does run at 5 minute headways, but splits the capacity between the Green and Blue lines.

The main point is that there is a lot of capacity on the Green Line yet to go, even if you only run 18 hours a day, and you expect everyone to have a seat, and run at today’s 10 minute headways (which is all today’s fleet can support, to increase headway we either need to increase speed greatly or add vehicles), and assume the average trip is 7 stations (Aaron Isaacs informs me it is 3.5 miles, which at 1/2 mile spacing is about 7 stations) (83,314 – scenario D). At the other end of the spectrum, if everyone expected a seat and was riding from Union Depot to Target Field, the capacity would only be 32,400 with today’s frequencies.

Since Minneapolis has additional capacity on its new rail line, and there’s a lot of developable land along the corridor, Levinson wonders: “Why are new corridors being subsidized for development?”

Elsewhere on the Network today: The Wash Cycle shares a photo from San Francisco showing how a bump-out makes a handy spot for a bike corral. discusses the stubborn resistance to bike transportation in Georgia. And Prince George’s Urbanist evaluates efforts to make a rail hub at New Carrolton, Maryland, more urban and transit friendly.

  • JacobEPeters

    Before anyone says it, yes, certain lines on the CTA are not operating with any rush hour capacity. The excess capacity on the CTA exists on the Orange, Green, Pink, & south side Red Line, along with off peak on most lines. TOD in north & northwest side neighborhoods along CTA lines that already are packed during rush hour will improve off peak capacity utilization, but it will also require expanding platforms on some lines & reorganizing some aspects of routing in order to meet new rush hour demand. TOD on the near south and west sides would improve utilization of capacity drastically, but there is only 1 TOD project that has been proposed that isn’t on an already very busy CTA line.

  • Concobhar Mac Conmara

    City also needs to expand lines. Create the gray line, extend Green line to 63rd and Dorchester, as well as 111th and Pulaski via Beverly and Mt. Greenwood, extend Orange south to Ford City, then east to Pulaski, then south to a terminus at 111th and Pulaski. Improves the transit for most of the South Side, especially with the impending Ashland BRT line and Red Line extension.

  • Yes, it makes no sense to invest in the capacity to move lots of people quickly in one place then allow all the development to occur elsewhere, even subsidizing it at times. This precise problem is exactly why so many transit projects “fail”. You could even say that this is why many of the original streetcar lines “failed” too as they couldn’t compete with publicly-funded roads.

  • neroden

    Zoning as it’s been done starting in the 1950s has been a curse. I understand the idea of keeping dirty industrial operations isolated off in a corner away from residential areas… but keeping shops and restaurants away from residents makes *no sense*, and that’s the basis of most zoning.