A Question Of Capacity – Reprinted from the Light Rail Transit Association

A repost from January 3 2018

A QUESTION OF CAPACITY

THE CAPACITIES of different modes of transport are generally quoted as 0-10 000 passengers per hour for bus, 2000-20 000 for light rail, and 15 000 upwards for heavy rail.

 

 

* Maximum capacity is only likely to be required for a few hours during peak hours, and even here there are likely to be variations both day by day and within each hour. The capacity required originates from the route’s social characteristics.

* As for the vehicles, buses have a comfort capacity equal to the number of seats, and a maximum capacity equal to seats plus standing load.

* In the case of trams, it is more complicated. The nominal maximum capacity is calculated at four passengers per square metre of available floor space (a reasonably comfortable level), plus the number of seats.

* As trams are designed to carry a large standing load, the ratio of standees to seats is quite high. The standing area is also important for the carrying of wheelchairs, pushchairs, shopping and sometimes bicycles. Some manufacturers quote maximum capacity using 6p/m2 while a figure of 8p/m 2 is used as a measure of crush capacity. This last figure is also employed to determine the motor rating of the vehicle.

* A further complication is that even when there are seats available, some passengers prefer to stand. This may be because they are only traveling for a few stops, that they want to stretch their legs, or may just prefer to stand.

* A tram’s comfort capacity can therefore be considered as the number of seats, plus the voluntary standees who may amount to up to 10-15% of the nominal maximum number of standing passengers.

ELASTICITY

* It is the difference between the average passenger load for any particular time and the crush load which gives light rail its Elasticity Factor, allowing it to cope with variations in conditions such as sudden surges or emergency conditions.

* Standing is made more acceptable by the design of track and vehicle, reducing the forces acting on the passenger to a minimum. This makes for a smooth ride, as well as ensuring ease of access, good support and the ability to see out without having to stoop.

* Where a route is mainly urban with short journey times, the number of vehicles required should be calculated on the nominal maximum. On longer journeys outside the central area, a lower level may be more appropriate, dependent on the route’s characteristics. Even on rural sections, there are likely to be a a number of short distance riders, and the loading factor will increase nearer to the urban area.

COMPRESSIBILITY

* While it might be thought desirable to offer every passenger a seat, it is in fact the ability to carry high loadings in a confined area (the Compressibility Factor) which enables light rail to achieve many environmental benefits, allowing large numbers of people to be carried without harming, and often improving, the features of a city.

* It is city centres where several routes combine that the most capacity is required. A typical situation could be a pedestrian street with six routes operating at 10-minute headway giving 36 double coupled trams per hour each with a capacity of 225. This gives a nominal capacity of16 200 passengers per hour which can be increased to 25 200 pph in extremis without extra vehicles.

Light rail is unique in this ability to operate on the surface with its capacity without detracting from the amenities which it serves. A further factor in setting the resources required is the need to lure motorists out of cars. The more difficult the traffic conditions, the higher the loading’s will be acceptable. It is however important that crush loads are not allowed for more than the shortest of periods on an infrequent basis, both to maintain customer satisfaction and prevent elasticity of the system being compromised.

* It is vital that public transport can cope with sudden changes in demand, such as extreme inclement weather or air quality violations which can cause private traffic to be halted. This is where the elasticity inherent in light rail is so beneficial in enabling an instant response in an economical fashion. A tram may be crowded, but its infinitely better than having to wait in the snow of smog until extra vehicles are brought into service.

* It is this unique combination of Capacity, Compressibility and Elasticity rather than capacity alone which makes light rail so successful as an urban transport mode.

* Note Statistics are based on Karlsruhe, using GT/8 cars

 

Comments

5 Responses to “A Question Of Capacity – Reprinted from the Light Rail Transit Association”
  1. Bill Burgess says:

    Zwei, this article reports the capacity for light rail is 22,200 per hour “in extremis” (based on Karlsruhe), but your previous, Jan 7 post cited “capacity in excess of 35,000 pphpd”. What is the most credible/comparable number?

    Are you suggesting that the Bloor-Danforth streetcar route carried 12,000 people per hour in the 1950s on any regular basis? If the max crush capacity of each car was 134 (see https://en.wikipedia.org/wiki/Presidents%27_Conference_Committee_(Toronto_streetcar)), that implies headways of only 45 seconds for 2 car trains. Was there any auto or pedestrian traffic or Bloor or cross-streets?

    Zwei replies: The LRTA article on capacity was published in the early 2020’s, while the traffic flows in excess of 35,000 pphpd topped about seven ago. A subway on Kaiserstrasse is about to open but planners are now saying they erred in putting all rail service underground and they should have retained tracks on the surface.

    The capacity of trams on Bloor Danforth has been well documented by the the TTC, much to the embarrassment of Vancouver’s engineering department.

  2. Bill Burgess says:

    Oops, 45 cars per hour,

  3. Bill Burgess says:

    I can find find 6,000 and 9,000/hr for the Bloor streetcar but no 12,000/hr.

    “Until the subway opened, service was provided on Bloor-Danforth by two-car trains of PCCs running less than 90 seconds apart… The design capacity (based on 75/car) was over 6,000 passengers per hour, and actual loads were above what is now considered a reasonable service design level.” (https://stevemunro.ca/2013/03/16/past-and-future-streetcar-service-capacity/)

    “Streetcar capacity was 9,000 passengers per hour compared to more than 20,000 passengers per hour carried by the subway line” (https://torontosun.com/2016/02/24/bloor-danforth-line-turning-50#:~:text=It%20was%20estimated%20that%20500%2C000,carried%20by%20the%20subway%20line)

    “Until the subway opened, service was provided on Bloor-Danforth by two-car trains of PCCs running less than 90 seconds apart… The design capacity (based on 75/car) was over 6,000 passengers per hour, and actual loads were above what is now considered a reasonable service design level.” (https://stevemunro.ca/2013/03/16/past-and-future-streetcar-service-capacity/)

    As you know, Steve Munro likes streetcars so I don’t think he would under-report their capacity. Nor would this TTC engineering report that argued for buying more cars to bring the Bloor line capacity up to 9,000/hr:

    “Major track reconstruction where required should therefore, be undertaken on these
    routes as set out in the attached memorandum from Mr. W.A. MacRae, and as shown on
    the accompanying plan, marked Exhibit No. 5.
    Route Passengers per
    Maximum Hour
    Street Cars Required

    Bathurst 6,100 70
    Bloor 9,000 174″
    (https://swanboatsteve.files.wordpress.com/2010/01/wepduncan19520603.pdf)

    The Karlsruhe system was/is great, but for comparative purposes 35,000 ppdpd (and I take this to be over a short stretch/on multiple lines) is not a credible figure for the capacity of light rail. It would be more convincing to cite actual peak hour numbers of light rail systems. What/where is currently the highest ridership in the world for light rail a) in mixed traffic, b) own ROW, and c) segregated ROW?

    Zwei replies: It has been well established that the Bllor Danforth route operated coupled sets of PCC cars

    A quote from our friend Haveacow, who is a transportation engineer from Ottawa. “Minor point, historically, the TTC did run coupled sets of PCC Streetcars on the Bloor-Danforth and Bathurst lines in the 50′s to early 70′s. The Bloor-Danforth line ended service in 1966 with the opening of the first section of the Bloor-Danforth Subway Line. The Bloor-Danforth streetcar did move up to 12,700 passengers per hour per direction at peak. On the Bloor-Danforthline at the time, there was a coupled set of cars every 75 seconds (Always a streetcar car in site was the old moto).

    The figure of 12,000 pphpd (a conservative number evidently) figure is also credited to several transit based magazines.

  4. zweisystem says:

    As the LRTA defines LRT as a mode that can economically cater to traffic flows between 2,000 and 20,000 pphpd+ any argument about tams carrying high volumes of customers is moot.

    As most tram networks carry their highest volumes of traffic within the city centre, the ability to cater to high traffic flows is necessary but as the route travels to its terminus in the suburbs, the need for such high capacity does not exist. What is forgotten, most subway routes contain the ridership of 3, 4 or more tram routes, any comparison lacks validity.

    In Europe, most major cities operating trams offer huge ridership numbers close to the city centre, in excess of 20,000 pphpd on several routes during peak hours.

  5. Haveacow says:

    Unfortunately, the TTC will never be able to do run line capacities like that ever again due to one simple fact. When the Bloor-Danforth streetcar line was able to do this, the TTC had a streetcar fleet of over 700+ streetcars. Even though the new Bombardier Flexity Outlook LRV’s are much longer than previous TTC streetcars a fleet of only 204 just doesn’t have the size to accomplish the needed frequency of service. At it’s peak in the mid 1950″s the TTC had 750 PCC’s and over 125 remaining Peter Witt’s. Even with the TTC planning to order between 60 to 80 even larger LRV’s in the next few years, that kind of passenger carrying capacity is nearly impossible without leaving multiple lines without any service at all.

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