09 July 2014

The Path to Level Boarding

The California High-Speed Rail Authority recently abandoned its plan to procure trains by piggybacking on an Amtrak order of new trains for the Northeast Corridor.  This news isn't all that surprising: the two have such different requirements that it never made sense for California to hitch its cart to the wrong end of Amtrak's horse.

The effect is to free California from the prescribed platform interface in use on the Northeast Corridor, where the platform edges are located 48 inches above the top of the rail and offset laterally by 67 inches from the center line of the track.  An earlier recommendation that Caltrain should use high platforms to ensure compatibility with high-speed rail, especially in highly constrained stations like San Francisco Transbay, still stands.  The specific dimensions of the platform interface, however, can be optimized for California at a height less than 48 inches and offset greater than 67 inches.

Let us briefly review the Unique Local Conditions present in California:
  • "blended" commuter / HSR service
  • bi-level commuter rolling stock, both in the north (Caltrain) and south (Metrolink)
  • single-level HSR rolling stock, at the CHSRA consultant's insistence
  • a strict requirement for level boarding, per Americans with Disabilities Act, unlike Europe
  • no pre-existing level boarding standard, unlike Amtrak's NEC
  • a very tall (17 feet, AAR Plate F) loading gauge, unlike Amtrak's NEC
These conditions have direct implications for the upcoming procurement of Caltrain EMU trains.  Caltrain recently sent out a Request For Information to train manufacturers.  This RFI discusses the platform interface issue but considers only a high option (~50") and a low option (~25").  Are those really the only options?

Future trends in high-speed train design

Stadler EC 250, with a 760 mm floor
Europe, where "blended" high-speed rail is the rule rather than the exception, is gradually standardizing around two platform heights: 550 mm (21.7") and 760 mm (29.9").  Accessibility laws are becoming more stringent, forcing train floor heights to match the platforms for seamless level boarding.  The traditional single-deck high-speed train designs now operating in Europe, including recent models designed in the last decade such as the AGV and Velaro-D, still don't allow level boarding. Two or three steps are necessary depending on platform height, to the increasing dismay of advocacy groups for persons with reduced mobility.  The next generation of single-deck high-speed trains, of the sort that California might order later this decade, are designed for level boarding with entry floor heights of 760 mm; for example, the Talgo Avril and the Stadler EC 250 (shown at right).  Accessibility requirements will eventually leave the big three manufacturers (Alstom, Bombardier and Siemens) with no choice but to follow suit and offer high-speed trains capable of level boarding, most likely at 760 mm.

Not too high, not too low, just right

760 mm is a good compromise platform height because it satisfies two conflicting requirements:
  1. it is low enough that a Caltrain or Metrolink double-deck EMU could be designed with entry doors on the lower floor without making the train excessively tall, and
  2. it is high enough that a single-deck high-speed train can be designed with a continuously accessible floor with no interior steps throughout the entire length of the train, per ADA requirements.
Floor heights lower than 760 mm quickly become impractical for providing accessibility throughout all cars of a single-deck high-speed train, as required by Federal Railroad Administration regulations that implement the ADA (specifically 49 CFR 38.175).  The train's floor must rise over wheels and traction gear that can be significantly taller than 760 mm, so lower floors lead to impractically long interior ramps or lifts to enable wheelchairs to move about between train cars.

Floor heights higher than 760 mm are not practical for boarding and alighting from the lower level of a bi-level EMU, and push the entry doors out over the wheels at the ends of train cars, resulting in unevenly-spaced doors that may impede passenger flows on station platforms and increase station dwell times.

Stepping up to 760 mm (30 inches)

The transition to level boarding, regardless of the selected platform height, will not take place overnight.  For logistical and financial reasons, there will be a period of several years during which commuter trains will serve a mish-mash of old and new platforms at differing heights.  To allow uninterrupted service through this transition, the trains will require built-in movable steps to serve both heights.

This isn't a new problem.  Numerous trains worldwide have been designed to address it, as seen in the image and videos below.
YouTube videos of moving steps:

Step deployed for a low platform on a Paris
commuter train. Photo credit: Poudou99

This is however a deceptively difficult engineering problem, because the step mechanism and controls must be incredibly reliable to prevent trains from breaking down and disrupting service.  Consider that a single train opens a dozen doors at every stop; if 100 trains a day make an average of 16 stops each, there will be about 20,000 door cycles per day.  If each door cycle has a failure probability of just 1 in 100,000, we are still left with an 18% chance that one or more doors will fail and disrupt service on any given day.  That's why even a 1 in 100,000 failure probability is not acceptable for a door mechanism, as a number of operators have found out the hard way.

The lesson is clear: these mechanisms must be designed with the utmost simplicity and reliability.  For Caltrain's new EMU fleet, that could be nothing fancier than a single step deploying from each door, as shown in the cross-section diagrams below.  Train floors are drawn in dark red.


The EMU steps, shown in the third diagram from the top, are a bit taller than one would like with an 11-inch rise.  That's 1 inch taller than today's first step, but probably acceptable for a temporary transition period until all platforms are raised and the step mechanisms can be permanently retired.

Note also that as drawn here, the extra width of the new cars would place the new platform edge 70 inches from the track center line, a full six inches outside of the nominal Plate F loading gauge.  This dimension might ease any concerns from Union Pacific that high platforms would interfere with freight service, or from the government about STRACNET clearances.

This is a compromise solution, and as such it isn't ideal under every criterion:
  • the floor height is a bit higher than one would like for a bilevel EMU
  • the floor height is a bit lower than one would like for a single deck high-speed train
  • there is a failure-prone moving step mechanism
  • the step height is awkwardly tall
Nevertheless, this compromise, or one very similar to it, provides the only viable path toward a high-speed rail system that is seamlessly interoperable with Caltrain and Metrolink in Southern California.  The guiding principle of "any train, any track, any platform" will pay off with billions in infrastructure savings state-wide, more efficient utilization of station platforms, and valuable minutes saved on every connecting trip.

Gradual Transition Strategy

Getting from today's 8-inch platforms to 100% level boarding isn't something that requires a mega-project right after (or worse, during) electrification.  It can be done piecemeal, on a station-by-station basis as funding becomes available for each, exactly like the 37 platforms built in the last 15 years.  The timeline can expand or contract to match any budget.  Here's the simplest way to get from here to level boarding:


Thinking about this transition ahead of time, and designing the EMU fleet around the new platform interface, has essentially zero up-front cost.  In the long run, doing it right the first time saves money because we won't have to do it over in order to achieve the numerous benefits of level boarding.

Caltrain may not fully realize this, but their decision about the platform interface for their upcoming EMU procurement could set a generational precedent for the entire California rail system.  Will they give it the consideration it deserves?

39 comments:

  1. What can we do to actually make this happen? Do we know when the new level boarding heights will be decided, and if there will be a public comment period?

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    1. The new boarding height will be decided in the next few months as the EMU RFP is prepared, and it remains to be seen whether Caltrain staff will even be aware of having made a choice--never mind the far-reaching implications of that choice for decades to come. I sincerely hope this key decision will be given the careful and deliberate attention it deserves.

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  2. The norwegian version of the Stadler Flirt is built with an floor height of 800 mm and is also widened to the larger loading gauges of Scandinavia, allowing 2+3 seating. As already mentioned, this is the way the European market will go. If California doesnt choose the high floor Shinkansen model, wide body trains with low to medium height platform is the way to go.

    The Scandinavian version of the Flirt will also run as a high speed (200 km/h) service between Stockholm and Gothenburg starting in 2015. It will only be One step up from the 580 mm swedish plaform height, and a small ramp for wheelchair passangers. (you can find more information about this new service here: http://www.mtrexpress.se/english)

    Greetings from Sweden

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    1. It would be really nice if the USA could join Europe and continue the development of modern and effective low floor trains. High floor trains might at the first glance look like the best solution but im not sure that holds in the future.

      I have made i sketch illustrating the possibilities of the 760 mm platform height:

      https://flic.kr/p/ofHPMN

      Greetings from Sweden

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    2. Here is a more detailed view of how a low floor wide body TGV may look like in 10 to 20 years. As you said, "Accessibility requirements will eventually leave the big three manufacturers (Alstom, Bombardier and Siemens) with no choice but to follow suit and offer high-speed trains capable of level boarding, most likely at 760 mm."

      https://flic.kr/p/oi1nvw

      Greetings from Sweden

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    3. Thanks Erik. I think it's important that Caltrain make the effort to go all the way up to the 760 mm standard, because that's the direction in which the entire European HSR market is going. This will enable seamless interoperation with HSR at SF Transbay, Millbrae and San Jose--not to mention Burbank, Los Angeles and Anaheim.

      "Blending" is more than a buzzword, it is a good idea that must be implemented correctly and completely. There is no room for half-measures.

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    4. Clem,

      "Blending"is a political slogan; no more, and no less.

      "Blending" is a polotiical exercise, about politicians in the Peninsula exercising their political power to force early (mis-) "investment" in the so-called "bookends"..

      You know and I know that this "early investment" is INCOMPATIBLE with high-speed rail. The signalling system which Caltrain had pre-selected, and will install on the "Blended" segment, is INCOMPATIBLE with the requirements for *any* HSR signalling system.

      You know that, I know that, and you know that I know that. You and I both know that Caltrain's "Modernization' staff is incompetent: so incompetent, that when the issue of incompatibility is raised to them, they reply that "hsR wouldn't have given us the money for CBOSS if it was incompatible".?
      Yet the two signalling systems *ARE* incompatible. (In many ways, more so than AM and FM radio are incompatible. Just in case the CalMod "director" is reading).

      So, Clem: . just *why* do you think Caltrain will care about "compatible" platform heights? Especially given CHSRA's Technical Memoranda, which clealry dictate airline-style "ground-side" and "air-side' separation. Complete with space for airport-style, captive-market, "mezzanine" (read: monopoly rent extraction) retail on the "air" (train) side?

      Please explain how platfform-sharing is acheivable under that regime.
      Because *I* cannot see how it can be accomplished.

      i mean, we're talking airport-style secured, segreated areas; versus the (cost-effecitve and sane) Caltrain "Proof-Of-Payment" system. Those are incompatible. They cannot be reconciled.

      And that incompatibility is the *ONE* thing on this blog, which a public-policy graduate, who did community outreach for a new BART station, is most likely to understand.

      On the dark sid,e perhaps such concrete-intensive, transportation-industrial-complex profit-making, segregation of passengers, is seen as desirable. Who knows......


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    5. I think it is slightly presumptuous of you to tell me what I know and don't know. That being said, I prefer to focus on the future and try to affect the decisions that are yet to be made. The new platform interface is one such decision, and it will be made very soon. That is where long-term value can be added.

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    6. Clem,

      I apologize, sincerely, for presuming to you what you do or don't know. I was thinking of issues like signalling -- where CBOSS is incompatible with HSR. I think we agree on that much.

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  3. I would just like to say that this is a well-written, clear, concise, informative, informed and useful article.

    It is 10000 times as useful as anything that has ever come out of Caltrain or CHSRA.

    Thank you.
    Well done.
    That is all.

    I could end on some downer about being ignored here on this critical issue as on all the other points, but let's all pretend the future will be different from the past, shall we?

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    1. Plus c,a change, plus c'est la me^me chose.

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  4. @Clem, like you said, 760mm is a compromise solution. Certainly 50inch is much more desirable for HSR trainsets because it enables all the mechanical and electrical components to be put underfloor and thus have lower center of gravity.

    The cost difference of building platforms to either 760mm or 50inch would be small for existing stations, and next to nothing for new stations. Caltrain had built many temporary stations for its various projects in recent years, the transition from existing 8inch to 50inch would be no different: build temporary platforms next to existing stations for older trainsets while rebuilding existing platform to final height.

    The advantage of bi-level passenger cars is marginal due to the need to include stairs. So instead of arguing for 760mm platform height just to enable Caltrain to order bi-level cars and put the doors at lower level, perhaps convincing Caltrain to order single-level trainsets is a better choice, which has the added advantage of conductors needed to walk through the cars once to check tickets.

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    1. Interesting thought.

      If the advantage of bilevel cars were truly so marginal, then they wouldn't be such a ubiquitous solution to capacity limits in so many cities around the world. And you can be sure that Caltrain will be severely capacity-limited once HSR is blended into the corridor. So I remain convinced that a large bilevel train (making full use of the generous clearances available on the peninsula corridor) is the right solution for Caltrain to make the most of what track capacity will be left.

      As to conductors checking tickets, what century is this? POP fare inspectors usually work in roving teams, with one person taking each floor.

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    2. There is actually room for some components under the floor. 760 mm is more like a medium height, about 400 mm higher than the bottom floor of the TGV Duplex. As the 760 mm standard mature there will be components designed specifically to fit this space. Not all will fit but a lot.

      In a high floor car up to 100 persons with luggage is moved up about 500 mm compared to a 760 mm car, that also affects the center of gravity. A low floor design may also reduce the overall height thus reducing drag and increasing wind stability.

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    3. More to the point, there really is no good transition story from 8 inch to 48 inch platforms, for either Caltrain or for (portions of) Metrolink. The cost of Shinkansen, Acela and Chinese HSR compatibility is either many years (decades?) of service interruption for Caltrain and/or procurement of an oddball high-low fleet with significant costs and service limitations.

      Compare with the much poorer
      http://caltrain-hsr.blogspot.com/2009/09/platform-height.html
      http://caltrain-hsr.blogspot.com/2010/11/future-emu.html
      or look at the complete messes (trap doors, mini-highs, hopeless levels of inefficiency for decades and decades) of the North East Corridor.

      In contrast, the engineering compromise outlined in this article above comes with an outstandingly good and achievable transition plan for Caltrain (and parts of Metrolink), and would leave us with a compromise-free (other than being a few inches too tall, if double deck) Caltrain fleet post transition.

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    4. Unless you want to close down Caltrain for a few years while they build all of the platforms there's going to be a transition period while the level boarding platforms are built, whatever that height turns out to be.

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    5. Reality Check15 July, 2014 14:53

      50 inches is just too damn high, so I vote for 760mm (30 inches).

      Easier, less costly transition and doesn't preclude bi-levels.

      Ticket checks (POP or otherwise) work just fine on bi-levels, so that's a nonsense argument for 50 inches or the single-level cars that height implies.

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    6. There are bi level cars that go to 48 inch platforms

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    7. Reality Check15 July, 2014 15:22

      Which ones and where are they in use today?

      How do wheelchairs board and where on the car are they accommodated?

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    8. http://en.wikipedia.org/wiki/E4_Series_Shinkansen

      They flit about in far off exotic New Jersey a lot and are fairly often spotted in Montreal, Boston and soon Baltimore and Washington DC.

      They board from the platform and ride inside the car?

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    9. Reality Check15 July, 2014 16:11

      Looking at this photo, it appears you can only move past the door vestibule via stairs. If so, the E4 doesn't work for wheelchairs, does it?

      Shinkansens don't "flit about" anywhere in North America, so what cars are you talking about and how many and where on-board are wheelchairs and riders unable to use stairs accommodated on them?

      The original point was that 48-50 inch doors are too high to allow bi-levels wherein wheelchairs and non-stairs-capable riders can reach the lower floor. You'd either have to build a car with internal ramps or put the doors on the mid-level of tri-level cars such as Caltrain's Bombardiers. Neither sounds like a great option.

      That's part of why I think 30-inch platforms are so much better for Caltrain than 50-inch.

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    10. Reality Check: The doors aren't all the way at the ends of the cars, so there's some area which is level with the platform at the ends of the cars. That's where disabled passengers sit. It doesn't allow them to traverse the train, but that's true of nearly any bilevel design with a few exceptions - gallery cars and the Talgo 22 concept.

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    11. Reality Check15 July, 2014 18:40

      Ah, OK. Thanks Joey.

      So it's a tri-level car with 3 levels. The doors are on the mid-level as can be seen in this video of an E4 departing.

      I also found a video showing seats being turned (holy crap, they appear to be powered!).

      And (FINALLY!) -- a hard-to-find POV video traversing the interior of an 8-car E4... with a combination of lower and upper floor car traversals. Owing to the tri-level design, you'd have to negotiate 2 sets of stairs per car traversed. Not the most wheelchair- or disabled friendly train ... but still not totally unserviceable as long as they reserve some mid/door-level seating and spaces for those folks.

      Oh, and here's the cherry on top: the E4s have even got an on-board wheelchair elevator, as this POV video shows. Unbelievable! To be avoided if at all possible!

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    12. They had a legacy system to cope with. they figured out how to do it which means they could do it in California too. Since trains in California aren't going to be running in Japan it would be wise to explore other options but that doesn't stop the trains in Japan from running. Or the ones in far off exotic Maryland. or ones in California if California examines all the options and decides to use Shinkansen platform heights.

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    13. The way I see it, there are a number of circumstances that set Caltrain apart from other rail operators:

      1) a non-negotiable requirement for short and predictable station dwell times. Successful sharing of track infrastructure with HSR requires high average speeds for Caltrain, and the best way to speed those up is to attack the slowest portions of the trip, namely when the train is stationary. Every second counts. That's why level boarding is so important, and why we need to think about smoothing passenger circulation both on the platforms and on the train for all kinds of users (pedestrians, wheel chairs, bikes, strollers, lugguge, etc.). It makes sense to have doors spaced evenly along the train with spacious access inside rather than cramped vestibules, unlike all the examples cited above.

      2) It's not just about wheel chairs. Caltrain has an unusually large portion of riders who bring their bikes on board to complete the first mile / last mile portion of their trip. I believe the figure of ~6000 daily bike boardings (over ten percent of overall ridership) is unmatched anywhere else in the nation. To keep dwell times low, the new level boarding interface must lead directly into spacious areas where a large number of bicycles can be quickly stored. That's why boarding on the lower level makes sense, and it's also a reason why extra-wide trains make sense.

      California has no legacy system, and it didn't necessarily make any sense to extend the Pennsylvania Railroad's legacy all the way out here. There is an opportunity here to adopt a new standard that meets the specific needs of California, needs that aren't particularly pressing in places like the Northeast Corridor or Japan.

      As for HSR in California, they have clearly stated that from a regulatory and commercial standpoint they will go with a single-level architecture. The E4 Shinkansen, while an interesting feat of vehicle packaging, is not relevant. What is needed is a platform interface that meets every operator's requirements, and 30 x 70 inches may just be it.

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    14. If Caltrain ordered 6-car or 3-car fixed sets, full-width and door-less gangways can be included in the design, similar to newer rapid-transit trains. Perhaps this would provide enough space for wheelchairs and bikes.

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    15. And doing something different than the rest of the country will be doing will be okay because just like trains from Japan won't be running California, except for the daily land cruise that toddles in, the trains from Chicago won't be running in California either. That doesn't make the trains in Japan or Pennsylvania evaporate.

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    16. Clem: How to keep dwell times short when 10% to 15% of your riders have bicycles? Put a bicycle rack for two, one above the other, on both sides of each level-boarding door-way pair. The car-length aisle would be off-center opposite the door-ways (bicycles are about 6 feet long) but still would leave enough room for easy transverse passage. The location of an arriving train’s open bike-carrying positions determined with bike-rack-occupation-sensors could be transmitted to stations ahead. When informed about the location of open-bke racks an experienced commuter could board a train with his bicycle without breaking stride.

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    17. In the Northeast, single-level (and some bilevel) trains with 48" entry height have doors with trapdoors revealing steps for serving low platforms. Instead of having two double-wide quarter-point doors, they have a single double-wide mid-car door, without a trapdoor, and two single-wide car-end doors with trapdoors.

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    18. How are the trapdoors operated? Knowing Amtrak, someone probably has to come through and open each one manually.

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    19. The MBTA trapdoors are manual, and I think so are the NJT and SEPTA trapdoors, but I remember seeing a YouTube video of an automatic trapdoor on a train in South Korea.

      One hitch, though: all the Northeastern examples I know involve unpowered cars, rather than EMUs. It is possible, albeit unlikely, that the trapdoor requires space that isn't available at a motorized bogie.

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    20. One of the perennial complaints about SEPTA is that they seem uninterested in suburban level boarding. The Silverliners go to high and low level platforms. So do Arrows.
      I'm sure someplace on railroad.net there is a thread scores of pages long about how they work. Or don't work.

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    21. The danger is of course that Caltrain and its rolling stock consultant may not look further than the Northeast Corridor. Such myopia would be terribly unfortunate when much better solutions exist.

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    22. one would hope that Caltrain look no further than whatever HSR decides on. Whatever solution or solutions California comes up with doesn't stop the doors from opening at low level SEPTA stations. That are mostly served by EMUs.

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    23. "one would hope that Caltrain look no further than whatever HSR decides on"
      Something about tails wagging dogs.

      Vaporware tails, for that matter, wagging real dogs.

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    24. ...not sure why I forgot that SEPTA runs EMUs.

      Never mind.

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  5. Clem, you express your concern that retractable steps must be very reliable. JR East uses retractable steps on all their mini-Shinkansen series to bridge the gap to the platform. Given the limited number of doors and the short dwelling times of those mini-Shinkansens and the bad weather conditions they sometimes operate in, you can trust them to be very reliable. In fact, the newest E6s still use the same basic step construction that the first 400 series had.

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  6. Reality Check16 July, 2014 15:38

    Level boarding "most important" for cutting BRT dwell times:
    Muni opposition to level boarding hinders bus rapid transit:
    "Having the bus-station platform level with the bus floor is one of the most important ways of reducing boarding and alighting times per passenger," the institute says in a document outlining its standards. "Passengers climbing even relatively minor steps can mean significant delay, particularly for the elderly, disabled, or people with suitcases or strollers."

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  7. The San Francisco Peninsula’s fragmented transit market suggests variable capacity consists are needed to efficiently address Caltrain’s current and potential traffic. For example TCRP’s Travelers’ Response to Service Quality data clearly shows that commuters are far more likely to use a transit service during peak-demand-hours if frequent late-evening runs are offered when total demand is often low. Major transit agencies are clearly responding to this insight. Chicago Metra’s hourly service until 12:40 am on the same lines that provide 2 hour mid-weekday headways is responsive passengers’ concern over lengthily waits while away from home. Five of Los Angeles’ light rail and subway lines offer 7-day 10 minute headways from 8 pm until mid-night even though they offer only 12 minute mid-day headways.
    A gradual introduction of EMUs presents an opportunity for Caltrain to complement their current uniformly slow accelerating moderate capacity rolling stock with light-weight quick accelerating level-boarding- finely adjustable length one operator EMU trains. Adding such EMUs to Caltrain’s rolling stock set would present a golden opportunity to recast Caltrain service to a form more responsive to SF peninsula riders desires. For example there are consistently strong ridership numbers when express trains are deployed. An initially modest number (Considerably less than half the current peak load requirement.) of Caltrain EMUs could be most profitably deployed (Meaning developing the greatest reduction in system operating subsidies possible.) with only one employee on each run which has the most stops during all SF Peninsula service hours. Since all-stop runs have fewer riders, especially when there are competing express trains operating during the same hour, these local trains could all be short requiring less than 200 feet of high-level-platform at each stop.
    Summary
    During the initial electrification period when both diesel and EMU trains would be operating during peak demand periods:
    (1) Diesel runs should only support skip-stop service.
    (2) EMUs should only be used for all-stop-service during peak demand periods and local plus skip stop runs during off peak periods. Since express service is always in greater demand at least two to four times more skip-stop than all-stop runs should be offered between peak demand periods−a service pattern now affordable with only one paid employee on board each EMU train.
    (3) In order to minimize the number of operating personnel required to deploy many independent trains EMU passengers should pay fares through a platform barrier system.

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