Adam Fitch wants to share this pdf with us:

Tunnel Vision vs Green Vision

See also, UBC line: The Adam Fitch proposal

…and the Vancouver Canada line case. The remarks apply also to LRT unless specified (another post has been dedicated to buses

In a nutshell, the person per hour per direction (pphpd) capacity a subway line can offer, is

    (capacity of a train) × (number of train per hour).

Like for buses, the capacity of a train is a function of different parameters, mainly person per square meter occupancy standard, and seats arrangement.

At the difference of low floor buses (and LRT), there is little “protuberance” (such wheel room) on high floor train, and technical room present in a train cabin rather under floor or on roof, are often the result of a tradeoff:

    train capacity vs easy maintenance

The theorical capacity of a train, is in fact a direct function of its surface:

      (length of the train) × (width of train).

…and a train length, is constrained by the station’s paltforms length, which are typically very expensive to expand.

Train capacity

below is an example of compared train capacity, expressed in term of surface able to accomodate passengers

Train consist Platform length width surface
Vancouver Canada Line 40 3 120
Vancouver Canada Line 50 3 150
Vancouver Skytrain (Expo line) 80 2.65 212
Paris typical subway line 75 2.37 178

For matter of comparison, the theorical Canada line capacity (with 50meters platform) is just 15% lower than on most of the parisian subway lines, such as its line 2 or 5: those lines carry ~100million riders a year.

Behind the seating layout, a train needs in practice several features to effectively reach its theorical capacity. Among them

  • Minimal unusable space between cars (and in cars)
  • Allow passenger to “overflow” from a car to another one

Intercirculation between cars, usually allows that, but again, some interciruclation layout can be more efficient than other:

skytrain


MP89CA_interior On top the skytrain MKII (second generation interior)intercirculation is narrow, impeding free flow movement from car to car, and blocking line of sight at the difference of the Parisian MP89-CA (bottom picture), where the train look like a single “big room”- credit photo top, the Translink’s Buzzer, bottom: wikipedia

Dwelling time and frequency

homogeneous occupancy of a train is also function of the door disposition, but the door layout affect primarily the dwelling time. Short dwelling time is important for a host of reasons, frequency being one of them, and frequency affcet the line capacity:

    interval between train can’t be shorter than the station dwelling time

It is hence important to have as much as possible doors, but also have them wide enough, to allow good in/out flow movement. It is also important to avoid that some doors, slow down the boarding/alighting time because they have to handle more traffic flow:

  • From a boarding viewpoint, where passengers have no apriori on the location of door on platform, the best way to do that, is to have all the doors equidistant (It make also the best use of the platform space)
  • From an alighting perspective, all doors on a car should be equidistant

skytrain

A 68 meters Vancouver skytrain consist, compared to a 75meterParisian MF01 5 cars consist (operating on line 2,5 and 9): the later has lower theorical capacity because it is narrower, but it has greater practical capacity due mainly to a better intercirculation. Furthermore, all doors are equidistant on the MF01 [1], while on the skytrain MK2, people waiting in red zone have to report on a nearby door zone slowing down the boarding. Similarly people standing in red zone aboard the train are too far from a door slowing down the alighting (or conversely limiting the practical capacity of the train by passenger reluctance to stand too far away of a door).

Track issues

A single track, vs a double track, at the end of a line could be used as a cost saving measure, but obviously it affects the frequency of a train line. That said, if the single track portion is short enough, the impact can be relatively minimal.

    Frequency can be be obtained by using a tail track to store trains

The possible frequency is then:

    ((time to travel for and back the single track) + (dwelling time × number of train to be stored) ) / (number of train stored).

As an example, at Richmond Brighouse station, on the Vancouver’s Canada line

  • the tail track past the station can accomodate one stored train [2], and the station another one
  • the travel time between Lansdowne and Brighouse is ~90s and a typical station dwelling time ~20s
2 trains run in one cycle on the single track , by using a tail track behind the termini station

2 trains run in one cycle on the single track , by using a tail track behind the termini station

2 trains can run every 4mn on the Richmond Brighouse branch of the Canada line.

Because one train can run every 4mn on the Airport line, it is possible to get a train every 80s, or 45 trains per hour, on the common trunk (Bridgeport-Waterfront)

Even, with 40meters long train, the Canada line could provides a capacity of ~15,000pphpd, assuming 330 passengers per train: that is 3 times the actual capacity. Greater frequency are theorically possible with the introduction of short turn train (avoiding the single track section):

3 trains running in one cycle, one being shorturned before the single track section, 2 using the single track section

3 trains running in one cycle, one being shorturned before the single track section, 2 using the single track section

PS The above numbers for the Canada line, assume the availability of rolling stock, power supply, track signalling, and fast operating switch: All those could need to be upgraded, as well as the stations along the line to handle the corresponding increase in ridership, but it could be no need for heavy civil engineering work/track reconfigutation toward a capacity increase of 15,000+ pphd


[1] Materiel roulant MF2000, seance 12/12/2000, Conseil d’administration du STIF

[2] Addressing Canada Line capacity questions, Translink, June 3, 2010.

Post edited after comment number 3

Addendum

I have noticed that Translink has made public on Monday its full study [5], which looks pretty comprehensive, so I have to swallow back some chuncks of this post, to recognize this fact. An important figure from this study is how the line affect ridership region wise, and more especially the busiest segment of the Expo line:

2041 AM peak transit flow on on the Broadway-Commercial / Main-Terminal Expo line segment

Mode pphpd
Business As Usual 23,104
LRT 22,165
Skytrain 18,981
Combo 20,007


The above illustrates that not extending the Millennium beyond VCC Clark, impose a cost on the Expo line… just to be able to cope with the demand on its busiest segment. This cost can be eventually tremendous, [6] has advanced number above $1 Billion to upgrade the Expo line capacity above 20,000pphpd.

A Potential Broadway subway alignment (notice the 2 stations on the UBC campus)

Lot of activities on the Broadway subway front those days:

  • A KPMG study financed by the City of Vancouver
  • The finding of what is presented as a Phase 2 of the UBC line rapid transit study: One year study for a 9 pages pamphlet : Isn’t it pathetic? No, now Translink has made available the full 406p study on its site [5]
  • A Vision’s campaign for the Broadway subway, with its Town hall meeting sunday March 10th

The results of the KPMG study are unsurprisingly aligned with the buyer expectation, City of Vancouver. Nevertheless, the study addresses an important global economic aspect of why rapid transit is needed, and we will have probably the opportunity to develop on this aspect in the future

The March 10th Vision town hall meeting, or Broadway subway Rally

A gray hair, subway hostile crowd was out in full force at the St James Community Hall in the heart of Kitsilano, and was seeming to set a pretty dominating adversarial tone for this meeting. It turn out that the Geoff Meggs presentation [1] was able to keep their ire under control. After that, the “anti subway” lobby was not really able to come with any constructive comment/question: Usually sarcastic, and more often that not fear-mongering and deriding UBC students.

The refreshing voice of one of them was in fact framing the debate:

  • The young from UBC, representing and wanting to be the fuel of the future of the regional economy vs
  • The gray hair, living on over-inflated real estate, contemptuous of everything West of Alma, and East of Arbutus, and representing a past era.

In that sense, this meeting probably achieved its key objective. Some tried to make the case for an LRT, based on the premise that for a subway, you can have many LRTs. Geoff Meggs admitted that he has to believe the Translink engineers more than the “engineer” Patrick Condon (the champion of this idea).

The Phasing of the Line

Richard Campbell questioned about that. It is probably the only way to see this line somedays as well as the best way to move forward as suggested before. That allows to defer technology choice west of Arbutus to a later date. Below some useful numbers from an Ottawa study [2]; which are relatively inline with a Parisian study [7]; for the matter relevant to the Broadway Subway:

Component Ottawa Cost [3] Paris Cost [7]
Twin bored tunnel (3m radius) $45M/km
Single bored tunnel (4m radius) €25M/km
Track/Electrical $55M/km
Underground Station (up to 30,000pph) $40M €32M
Open air Station (up to 30,000pph) €27M

The total leads to a $2Billions for the Broadway line, adding a 50% contingency fund as assumed in [3], brings the cost to $3Billions, not including rolling stock and land acquisition.

The numbers suggest that a first phase VCC Clark/Arbutus could come at a $1.3Billion price tag.


For matter of comparison, the 6km extension of the metro line 14, including 4 new stations North of Paris, in a arguably much more complex typology, is budgeted at €1.2Billion [8].

[5] estimates a first phase ending at Arbutus, budgeted at $1.5B and states that:

    The economic assessment of phasing RRT is positive with a benefit:cost ratio of 2.7, vs. 2.3 if built to UBC initially.

Phasing can arise some challenges,

  • It needs to make sense from a Transit network perspective to allow to leverage the new line, and provides an efficient reworking of the bus network

if tunnel is done in several phases

  • More well access to tunnel could be necessary
  • Duplication of starting cost and acquisition of expensive machinery like tunnel boring machine (TBM)

So it is fair to examine the idea to build all the component potentially requiring a TBM in a single phase, and defers later investments at an ulterior date.

  • The drawback is that we can have a sleeping investment not generating revenue, if we end up to build unused tunnels

Building technique

Oak station as envisioned in [2], is de facto assuming a cut and cover method for the station, and a twin bored tunnel. credit photo [2]

The twin tunnels option should also be considered as a starting default point, not as a political statement, like it seems to tend to be done in Vancouver. Considering the topography and traffic level, a cut and cover method could be applied reasonably as soon as West of MacDonald under 10th avenue. This method properly deployed doesn’t need to be despised on the ground of a bad experience, and is still routinely used around the world, including under temporary decks [4]:

Paris Line 4 extension Cut and cover, performed under temporary deck do minimize surface impact, at very busy  Paris's Porte d'Orleans

Paris Line 4 extension Cut and cover, performed under temporary deck do minimize surface impact, at very busy Paris’s Porte d’Orleans

The advantage of it, is that it allows a good phasing of the line in the vicinity of Arbutus.

It is also possible that in the case of the Broadway line, especially East of Arbutus, an single large bored tunnel accommodating stacked tracks north of Broadway could make sense, since, taking account of the topography, it could allow a better access to platforms in both directions:

The Line 9 in Barcelona has adopted a tube large enough to accommodate stacked trains (like on the Expo line), encompassing the station platforms, as well as electrical sub stations, cross over, and storage tracks all in the single bored tube. The impact of station on surface is then limited to the access well: In the Broadway case, it allow tu run the tunnel North of Broadway, and still have direct access to platform in both direction

The Line 9 in Barcelona has adopted a tub large enough to accommodate stacked train (like on the Expo line), encompassing the platform, as well as electrical sub station. cross over, and storage track all in the single bored tube. The impact of station on surface is then limited to the access well: In the Broadway case, it allows to run the tunnel North of Broadway, and still have direct access to platform in both direction

It is worth repeating that there are host of options, and none should be despised on pure political ground, and the one selected should be on the ground of best value for the $.


[1] It was in fact a rehash of a presentation done by the Vancouver engineering department to city council: Broadway Rapid transit, November 27, 2012

[2] Development of a downtown Transit solution and network implications, MacCormickRankin Corporation and Delcan, April 2008

[3] Prolongement du RER E, etude technique Traces gare et tunnel

[4] Prolongement de la ligne 4 du metro parisien, Lot 1, des techniques variees pour un lot complexe et delicat, V. Dore, B. Bizon, F. Billon, S. Leroux and L. Petit Jean. Tunnels et Espace souterrain, Nov/Dec 2010.

[5] UBC Line rapid transit study: Phase 2 Evaluation report Steer Davies Gleave, August 2012

[6] Expo line upgrade strategy SNC Lavalin and Steer Davies Gleave, September 21, 2010

[7] Arc express Etudes, insertion de traces, impact sommaire et redaction du DOCP, Setec Tpi, Xelis and Ingerop, 2009

[8] Metro ligne 14: Prolongement de St lazare a mairie de St Ouen, April 2012