Knees, Feet and the Interborough Express [corrected]
By John Pegram[1]
While studying railcar capacity for the Interborough Express (IBX) project, I have discovered that transit planners often do not take account of knees and feet of longitudinally seated passengers when estimating space available for standees. Because of the need for knee and foot space for seated passengers, crowding not only adversely affects standees, but also the seated passengers.
Here is a recent photo I took in a typical NYC Transit subway car on the 6 line:
Note first that the bottom of the seat is at least five inches from the car wall at the right edge of the photo. Ideally, passengers can sit with their feet flat on the floor, as the woman in the foreground is doing. For most adults, the knee and part of the leg extend beyond the seat edge. And, naturally, their feet extend further.
I am a 5-foot, 10-inch tall adult male. When seated in a subway seat, with my feet flat on the floor, the tips of my shoes are 32-inches from the car wall, protruding about 14-inches beyond the seat edge. Thus, when seated in a typical 18-inch-wide seat, the seat and I occupy an 18 x 32 inch space, with an area of 576 in.2 = 4 ft.2 = 0.37 m2. That is a passenger density of 2.69/m2. It is roughly comparable to the area allowed for an Economy Class airplane seat.[2]
When viewing seat diagrams for transit vehicles, there appear to be comparable areas allowed for knees and feet of passengers in transverse seats. For example, here is a diagram of a transverse seating area at the car end of a Siemens S700, 70% low floor Light Rail Vehicle (LRV), of the type used by Sound Transit in the Seattle area:[3]
The seats appear to be at a 30-inch pitch, with 6-inches of extra foot room for the front seats of each group. However, Siemens’ calculations of the number of standees (at crush loads of 6 or 8 riders per square meter) appear to have assumed the spaces occupied by longitudinally seated passengers’ knees and feet are available for standees.[4]
Four then-employees of the MTA wrote an excellent study in 2013, “Observed Customer Seating and Standing Behavior and Seat Preferences Onboard Subway Cars in New York City” (2013 Study).[5] That study divided several hypothetical and real subway cars into near-square rectangles, and considered the accessibility and desirability of each area of the car. An example from that study of a cab-less “Type B” R142 subway car, of the type that could fit on the IBX line, is shown below:[6]
Each of the 145 rectangles is identified by a row letter and column number. Each rectangular space is considered available for one of 40 seated passengers or one of 105 standees. Based on interior car dimensions of approximately 50-feet long and 8-feet wide, the dimensions of each rectangle is approximately 20.7 x 19.2 inches = 397 in.2 (= 2.76 ft.2 = 0.256 m2). That equates to approximately 4 persons per square meter overall.
The 2013 Study, however, apparently fails to consider the knees and feet of seated passengers. The seat rectangles are approximately the size of the seat itself and do not allow for the knees and feet of seated passengers. If a half-rectangle allowance is made for each set of knees and feet of seated passengers, the number of standees would be reduced by 20. Also, the poles located in three of the rectangles make it impractical for someone to stand there, so the number of standees at the density targeted by the 2013 Study would be further reduced by three. Therefore, at the study’s targeted density, the R142 Type B car capacity would be 122 passengers. Whether that would be comfortable will be a subject for a future article.
The R142 Type B cars discussed above are cab-less. According to the seat arrangement in the 2013 Study, the Type A cars, which have a cab, would have eight less seats and nine less standees than the Type B cars.[7] Therefore, the capacity of a pair of A and B cars at the study’s targeted density, would be—by my calculations—approximately 227 passengers.
Because LRVs, which the MTA proposes to use on the IBX line, are the same width as R142 and other NYC Transit A Division railcars, capacity analyses for the R142 is—to a large degree—scalable to LRVs with all longitudinal seating, or at least indicate an upper limit capacity at the targeted density. LRVs, like the S700 series, typically devote a greater percentage of their length to cabs as compared with R142 railcar sets, and the available passenger area may be reduced by stairs and by accordion walls where the LRVs are articulated.
The total passenger area of the Siemens S700 70% low floor LRV discussed above appears to be approximately 655 ft.2 (= 60.9 m ). The total passenger area of the R142 Type B railcar is 400 ft.2 (= 37.2 m2). Therefore, the passenger capacity of the 95 foot-long S700 with all longitudinal seating, at the density suggested by the 2013 Study, would be about 199. (Whether that density, or some other density, would be comfortable and appropriate will be the subject of another article).
This article expresses the personal views of the author and does not express the views of his employer, or any client or organization. The author has degrees in law and physics, and has taken several engineering courses. After five years of work as an engineer, he has practiced law primarily in the field of patents for over 50 years, dealing with a wide variety of technologies. He is a life-long railfan and user of public transportation in the United States, Europe and Japan.
As usual a PDF copy of this article is attached.
[1] © John Pegram, 2024.
[2] See Seat Guru, https://www.seatguru.com/charts/shorthaul_economy.php.
[3] Siemens, Low Floor Light Rail Vehicles brochure, pp. 25-26 (2021 ed.), copy of cited pages attached.
[4] Id. The 2024 version of this brochure no longer states a passenger capacity at 8/m2. See https://assets.new.siemens.com/siemens/assets/api/uuid:3ce5a359-5933-4f0b-8877-6e9aa3df13bd/Low-Floor-Light-Rail-Vehicle-Packet.pdf, pp. 30-31.
[5] Berkovich et al, “Observed Customer Seating and Standing Behavior and Seat Preferences Onboard Subway Cars in New York City” (2013 Study), preprint available at https://engrxiv.org/preprint/view/3421/6134.
[6] Id. at p. 21; see id. at pp. 7-8, 10-11.
[7] Id. at p. 21.
53rd used to (in 1989) carry 52.6k pph inbound in the morning rush in one hour, and that's with 30 tph of older B division trains. That averages out to 175 people/car. Still quite a bit less than the AW4 8/m2 240-person capacity, but it is an average sustained for a whole hour every weekday, and a lot higher than 122. And depending on the methodology, some fare evasion might've meant it was a bit higher in practice.
53rd in 1989 is crazy crowded compared to today, and I think people's tolerance of such crowding has decreased, but it does mean that that many people can fit in these trains.
> the same width as R211 and other NYC Transit A Division
Is this a typo? B division trains like the R211 are a lot wider than A division trains.