What is the Capacity of the Green Line?

While reading an excellent article by Yonah Freemark, Why should Chicago focus growth near transit?, I thought the Twin Cities should do the same thing. Taking advantage of existing capacity is far more cost effective than building new capacity (and yes, this applies to all modes). But what is the existing capacity of the Green Line? Well, that depends on assumptions and human behavior. In the table below I work through some scenarios based on assumptions.

First, how many hours per day is the Green Line operating? Second, what is the frequency within that time period? Third, how many cars per train are there? Fourth, what is the capacity per car (they are rated at 230, but this includes standees)? Fifth, how long is the line? Sixth, how long (how many stations) is the average trip? Seventh, how many directions are you considering?

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.

Thus, east–west transportation capacity is not the constraint in development along the Green Line corridor. (One could similarly demonstrate the under-utilization in the north-south direction on buses, and in all directions on roads).

Certainly load balancing is an issue, much of the capacity is “off-peak”, but that is what pricing is for. Higher loads would increase wear and tear on the cars, and add costs, but hopefully the added revenues would more than compensate.

Compare with current ridership of about 37,835/day (Sept. 2014).

Given there is also a lot of developable land in this corridor, why are new corridors being subsidized for development? [I do actually know the answer to this, it was a rhetorical question].

Capacity of the Green Line

 ABCDE
Fully UnconstrainedFully ConstrainedNeedlessly Constrained
Hours2424241818
Trains per Hour1212666
Runs per Day288288144108108
Cars per Train33333
Capacity per Car2301151155050
Capacity per Train690345345150150
Stations1919191919
Stations - 11818181818
Average Trip Length (in Stations)177718
Directions22222
DAILY CAPACITY7,153,920510,994255,49783,31432,400
Some scenarios describing capacity of the Green Line

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20 Responses to What is the Capacity of the Green Line?

  1. paddy April 26, 2015 at 9:09 am #

    While not a central to your point, which was interesting BTW, green line can not do more than 3 cars per train. The bridge over 280 can only hold 3 without blocking traffic

    • David Levinson
      David Levinson April 26, 2015 at 1:47 pm #

      Also station platforms would have to be reconfigured, in addition to other city blocks being blocked.

  2. Matt Brillhart April 26, 2015 at 12:49 pm #

    Perhaps someday instead of using 3-car LRV trains with 4(!) empty operator’s cabs and couplings taking up many feet of space in the middle of the train, we will come up with a replacement vehicle that dedicates more space to people. With our current equipment scheme, a significant percentage of the train space is not even available to passengers. I’d estimate close to 10% of the total length of the train is “wasted” (not including the operator’s cabs at the ends of the trainset, which are necessary of course)

    If we’re running 3-car trains all of the time, why not create a unique middle car that doesn’t have the unused operator’s cabs and instead dedicates that space to people?

    • Adam Froehlig
      Adam Froehlig April 26, 2015 at 1:21 pm #

      It would certainly be a capacity improvement. The main downside is that the operator (i.e. Metro Transit) loses trainset flexibility.

      • Matt Steele
        Matt Steele April 26, 2015 at 1:47 pm #

        An easier step would be to have LRVs that are 50% longer than our current LRVs. So a two car train would be the same length as a three car train. Two less cabs in the length of the train. The only downside would be that a single LRV train would be slightly less capacity than a double LRV train used during many off peak hours today. But it may make sense to run double-long LRV trains most of the day, with single-long LRV trains for night owl service.

        • Matty Lang
          Matty Lang April 26, 2015 at 2:38 pm #

          I wonder how that would impact the turning ability.

    • John Charles Wilson April 28, 2015 at 2:17 pm #

      Does anyone manufacture light rail cars that are like the NYC subway cars, where you can walk from car to car?

      • Nathanael April 29, 2015 at 8:40 pm #

        Yes, walk-through, articulated LRT cars are actually very common. If you want the extreme example, look at what Budapest uses on its busiest streetcar line.

        http://en.wikipedia.org/wiki/Avenio

        (NYC subway does NOT have walk-through cars; their gangways have been “for emergency use only” for decades.)

  3. David Markle
    David Markle April 26, 2015 at 5:22 pm #

    Neither speed nor frequency are likely to significantly increase, in my opinion, unless tunnels are constructed in downtown areas or at the University campus. Nevertheless, it seems obvious that the three-car trains presently run at nowhere near capacity, even during peak hours, except between downtown Minneapolis and campus for major athletic games. (These eye-witness observations support with Prof. Levinson’s calculations.)

    Very early (Peter Bell era) predictions of ridership were exaggerated, but it does appear that most who formerly rode the No. 16 bus now take the Green Line train. Though not faster, the train is a more pleasant ride. As I’ve pointed out previously, a streecar line would have been as pleasant at a fraction of the development cost, could have run on a more frquent schedule, and would have had better access (many more points of boarding and exit): would have been better for the elderly and disabled.

    As both Paddy and the Prof. observe, four-car trains will not fit, and would block numerous intersections, especially in the downtown areas, and most particularly in downtown Minneapolis where the Blue Line runs on the same tracks.

    Regarding Matt Steel and Matty Lang’s comments, the Green Line trains do need to be articulated to negotiate rather sharp corners, for example near the University stadium. Do LRV’s exist that are 50% longer than ours, with three points of articulation? Would such a longer LRV need to make those turns at a slower speed?

    • Matty Lang
      Matty Lang April 26, 2015 at 8:30 pm #

      It’s demonstrably false to say that the Green Line is not faster than the 16 bus. It may be close on the edges of the day when there’s no car traffic.

    • Adam Miller
      Adam Miller April 27, 2015 at 2:05 pm #

      Why is a tunnel needed near the University? Along Washington, there is very little conflicting traffic. What would a tunnel get you that signal priority doesn’t, especially as the main source of delay is the relative proximity of the East Bank, Stadium and Prospect Park stops?

    • Nathanael April 29, 2015 at 8:40 pm #

      In downtown Minneapolis, completely redoing the traffic signals to give the LRT priority would save a lot of minutes.

  4. David Markle
    David Markle April 26, 2015 at 5:33 pm #

    Speaking of capacity, New York City’s hundred year old system now has problems: see yesterday’s New York Times editorial, “New York’s Subway Madness.” (Sorry, wasn’t able to transfer an active link.)

    http://www.nytimes.com/2015/04/25/opinion/new-yorks-subway-madness.html

    • David Markle
      David Markle April 27, 2015 at 1:36 pm #

      Does Matty Lang mean the published schedule of the No. 16 bus (when it ran from downtown to downtown) was demonstrably false? I haven’t checked the current schedule for the shortened route, but it should be faster than formerly, because it now has substantially fewer passengers. True, the actual bus performance will vary in practice, but the Green Line has notoriously run inconsistently.

      So I’d welcome a well planned and documented comparative demonstration. But I won’t ride the whole distance to make comparisons, much less create a data table, because the No. 16 and the Green Line are both too slow. I don’t have the time!

      I’d rather get exercise. I point out that if I walk the 4 mile distance between the West Bank and my workshop in St. Paul, or take the Green Line 2/3 of that distance and walk the remainder, the train saves me little time. After several commenters on another site claimed it couldn’t be true that the train saved me only around 20 minutes, I timed both options on each of five consecutive walking days and found that on the average the train only saved me a little more than 15 minutes! Nothing false, all measured by clock (to the nearest minute) and odometer (to the nearest tenth of one mile).

      • Alex Cecchini
        Alex Cecchini April 27, 2015 at 1:49 pm #

        http://streets.mn/2014/05/16/travel-times-on-existing-central-corridor-routes/

        The Green Line did suffer poor/inconsistent travel early on. They have since come down and become more reliable.

        http://www.twincities.com/localnews/ci_27641549/green-line-trims-st-paul-minneapolis-trip-by

        It now takes 45 minutes end to end, down from 53 during early operation. 38 minutes is the time from Central to Nicollet – about 15-17 minutes quicker than the 16 used to do it (on average), and ~5-7 minutes quicker than the average 50 trip.

      • Adam Miller
        Adam Miller April 27, 2015 at 2:00 pm #

        There is quite a bit of conflict between your contention that the train is too slow and the observation that riding it saves you 15 minutes over a mile and a third.

        Assuming normal human walking speeds, it should take you 20-30 minutes to walk. Which means riding that distance takes you 5-15 minutes. Are you saying you’d ride the whole way if that last mile and a third took less than 5 minutes?

  5. devin G April 27, 2015 at 6:51 pm #

    The GL ridership is very poor the many times I rode it is rarely has more than 20 riders /car The 16/50/94 buses even had mre riders.Even some midday and peak trains are arriving down town with less than 30 riders in all 3 cars MEt COUNCIL need to start steering more riders from the special buses to use the LRT lines and the local routes .#111-113-114-11-134-133 .These buslines are duplicating services with local routes and LRT lines.

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