18 July 2015

News Roundup, July 2015

Cost of Dual Height Boarding: with its industry review of the EMU draft RFP, Caltrain sought feedback from vehicle manufacturers regarding the cost and feasibility of delivering vehicles with dual boarding height capability.  According to the latest EMU procurement update, the feedback received indicates that vehicle cost would increase by just 3 to 5 percent.  This small premium (roughly $20 million) all but ensures that the HSR project will be able to pay for this important compatibility feature.

New Rules for Electrification: the California Public Utilities Commission has released General Order 176, the Rules for Overhead 25 kV Railroad Electrification Systems for a High-Speed Rail System.  The new GO, effective as of 26 March 2015, will also serve as the regulatory framework for Caltrain's electrification project, despite the peninsula corridor not qualifying as "high-speed rail" as narrowly defined in the document.  Three major issues remain to be hammered out with regulators and freight railroads: (1) grade crossing warning systems, (2) vertical clearances, and (3) freight personnel safety and training for operating freight trains in electrified territory.  These three issues are minor and unlikely to require a new rule-making process.  The release of GO 176 is timely for Caltrain's electrification project.

Cap and Trade Maneuvering: at least two lines of attack are being pursued by opponents of Caltrain electrification and the high-speed rail project.  First, there is or will be legal action that seeks to deny the use of Proposition 1A HSR bond funding to pay for Caltrain electrification, based on the (quite defensible) argument that electrification isn't high-speed rail and won't meet the legal restrictions of the bond measure. Prop 1A high-speed rail funding accounts for the lion's share of the funding package for electrification, a contribution of $600 million.  The underlying calculus is that denying this funding would kill the electrification project. Second, there is or will be legal action that seeks to deny the use of Cap and Trade funding to pay for high-speed rail, based on the (quite defensible) argument that the greenhouse gas reductions from HSR will only occur far in the future, well beyond the time frame required by CnT legislation.  Both of these legal challenges can be neutralized in one fell swoop, by substituting HSR CnT funds for the HSR Prop 1A funds. According to Caltrain's EIR, electrification will reduce greenhouse gas emissions by 80,000 metric tons per year initially, increasing to 190,000 metric tons by 2040, largely by cutting automobile traffic.  It doesn't get much more short-term than that, and CnT funds come with far fewer strings attached than Prop 1A funds.  Look for the funding swap to occur this fall, when the nine-party MOU is revised to reflect the growing electrification budget.

HSR Business Plan Machinations: due to the lack of funding to build the extremely expensive mountain crossings, there are indications that the 2016 business plan for HSR will call for service to begin in the SF and LA areas several years before the Central Valley is linked to anything.  This should be of some concern to Caltrain because it would put HSR in direct competition with Caltrain for affluent tech commuters, no matter what they say.  If Caltrain is elbowed out of the lucrative express market, the loss of revenue will be entirely HSR's gain.  While this Bay Area mini-HSR might show an operating profit (as required by law), it could only do so with a hidden subsidy, provided in the form of extremely scarce and valuable rush-hour track capacity.  Competition is great, but the market mechanisms for sharing the peninsula rail corridor "fairly" (whatever "fair" means to each stakeholder) would need to be carefully developed.  Then again, this silly idea might just wither on the vine, since the letters 'H' and 'S' would be absent from HSR.

14 June 2015


Caltrain recently published their Electric Multiple Unit (EMU) Request for Proposals (RFP) in draft form, to obtain feedback from potential proposers prior to the formal issue of this document in August 2015.  Here are some initial impressions:

What's Pleasantly Surprising:
  • Level boarding is a serious consideration throughout the RFP.  Caltrain appears to recognize the importance of this issue: it's the Next Big Thing after electrification, and cannot wait until the next round of vehicle replacement in the 2050s.  The RFP shows that Caltrain is starting to walk the walk, not just talk the talk.
  • Platform sharing and full blending with high-speed rail is firmly on the agenda with "Option B," a dual boarding height train that enables an eventual transition to level boarding at 48 - 51" height.  This solution has been described and advocated on this blog as the best one available given the constraints of the problem.  Most people who reject this solution ultimately take issue with one of the constraints, but once you accept these constraints, "Option B" starts to make more sense.  Proposers are asked in the draft RFP to further evaluate its feasibility and cost impact.
  • In section 3.3.3, future capability for level boarding is described as ADA-compliant with a 3-inch maximum horizontal gap and a 5/8-inch maximum height mismatch.  Section 4.2.3 specifies a pneumatic leveling suspension to meet the vertical tolerance. It looks like Caltrain  is going the extra inch after all, which is commendable.
  • The vehicle static envelope in Appendix C is a full 3.4 meters wide, enabling the use of extra-wide trains, wider than the conventional AAR plates.  While Caltrain doesn't seem keen on 3+2 seating (something about the "middle seat" situation), extra width that takes full advantage of the static envelope is good for all uses besides seating.  Let's hope the proposers aren't timid about this.
  • While it isn't immediately obvious from looking at the raw numbers, the run times required in section are fairly aggressive and will require some sporty power-to-weight ratios.  This high level of acceleration and braking performance is good for the blended system and will ensure that the most can be made of shared tracks.
  • In section, door controls are required to be installed in the driving cab, offering the possibility of consolidating and automating a task currently performed by conductors.
  • In section 14.4, an automatic station announcement system is specified to automate a task currently performed by conductors.  This isn't exactly surprising for a modern train, but Caltrain and its labor practices sometimes seem stuck back in the 20th century.
  • In section 14.9, the trains are required to be pre-wired (if not yet equipped) for passenger Wi-Fi.  For a rail system that serves Silicon Valley, that's overdue by easily a decade.
  • No trap doors!  That always seemed like a horrible way to achieve level boarding.
What's Disappointing:
  • The RFP is highly prescriptive.  The cost of preparing such a voluminous requirements specification, and then to formally verify such a large number of requirements, will easily run into the millions of dollars.  So much for off-the-shelf procurement.
  • In section 2, no allowance is made for articulated trains (e.g. Bombardier Omneo) or for trains with mixed bi-level and single level arrangements (e.g. Siemens Desiro HC).  The desired EMU is prescribed as a set of traditional bilevel cars each about 85 feet long.  A better approach would be to define a minimum passenger capacity per unit length, leaving more room for creative and unconventional interior layouts.
  • Still no detailed thought appears to have gone into how to transition to level boarding under "Option A".  The height of 24 or 25 inches is intended to match Caltrain's existing Bombardier bilevel cars, which is a bit mystifying since there is no feasible transition to level boarding using these cars.  Section 3.3.3 basically asks for proposers to figure it out for Caltrain: "Heights below 24 inches will be considered for future level boarding if the Contractor can demonstrate conclusively that the height is advantageous for JPB’s envisioned service and compatible during the transition to that envisioned service."
  • Section 12 requires all doors of the train to open at every stop, as they do today.  To reduce wear and tear on the door mechanisms, modern vehicles often come equipped with interior and exterior push buttons for passengers to initiate door opening.  Instead of opening the doors by default, the crew-operated door control station should de-inhibit the doors to be opened only as requested by passengers at each individual door.
  • Section 2 envisions that trains would be lengthened from 6 cars (~150 m) to 8 cars (~200 m) at some future date.  This is far too timid a capacity expansion.  A more flexible and future-proof approach would be to order more 150 m trains and double them up-- after the necessary platform extensions are constructed at stations with the highest ridership.
What's Weird:
  • Section 2 requires shorter 6-car trains to have their performance de-rated (by software) to the same performance as a longer 8-car train.
  • Section 23.2.2 requires the delivery of 200 (two hundred!) 1/50th scale models of each car type for "internal and external distribution"... That's some serious schwag!
What's Missing:
  • "Option B" with dual boarding levels requires level boarding at 48 to 51 inches ATOR but fails to describe the basic platform interface dimensions, including height above rail, offset from track center, and tolerances thereon.  Proposers are unlikely to be able to design against such a critical interface when it hasn't even been defined.  This data should be agreed upon with the California HSR Authority, after some technical decision making that may have to occur sooner than they would like.
  • In section 3.3.3, Caltrain requires that "the entire platform interface system must also be usable during the transition from the current platform height to the level boarding platform height," a stealth requirement that makes "Option A" trains at least as mechanically complex as the "Option B" trains, by requiring boarding capability at two different heights (8-inch legacy and 25 inches with ADA-compliant level boarding).  A requirement of such great importance and design impact ought to be made more explicit, saying what it actually means and using the word "shall".
  • The door control system (section 12) envisions 100% manual operation of the doors by train crews.  This may not properly address the challenge of operating during a platform height transition, when each individual platform may need to be raised in successive construction phases to avoid closing the station or doubling the construction footprint for temporary platforms.  With manual door operation, the risk of human error resulting in opening a door at the wrong platform height will likely be unacceptable, particularly to regulators such as the CPUC.  It may be warranted, at the cost of some additional complexity, to require a platform sensing system that automatically inhibits door opening when the incorrect height is sensed, preventing crew errors and potential passenger injury.
Please use the comment section to add your own review of this document.

24 May 2015

Going the Extra Inch

Assisted level boarding on
Amtrak's Northeast Corridor
To enable wheelchair users to board a train without assistance, the Americans with Disabilities Act (ADA) requires level boarding platforms to have a maximum 3-inch horizontal gap with the train floor, and a maximum height mismatch of 5/8 inch (see 49 CFR 38.93).  When this specification is met, wheelchair users can safely and quickly board a train by simply rolling across the narrow gap between the platform and the train, giving it no more thought than when using an elevator.

Today, few commuter rail systems in the United States offer this level of accessibility.  The NCTD Sprinter (see video) may be the only one, and is often classified as "light" rail.  U.S. systems with level boarding (such as in the Northeast) have a gap of six inches or more between the platform and the train, requiring the use of bridge plates for a wheelchair user to board.  As shown in the photo above, train crew members must assist with the process of deploying the bridge plate, monitoring the wheelchair, and re-stowing the bridge plate.  Assisted boarding can easily extend station dwell times and cause delays, even on a rail system with level boarding.  These delays are allowed for by padding the time between successive trains, to prevent a delay from cascading to multiple trains.

So, just build the platforms close enough to the tracks and we're done, right?  It's not quite that easy.

Dynamic Vehicle Envelope

Dynamic envelope as defined
for Caltrain electrification
When trains are moving at speed, they can sway from side to side.  Suspension failures or shifting loads could even cause them to sag or lean to one side, requiring additional clearance between the track and nearby obstacles.  Station platforms form one such obstacle.  Caltrain's electrification RFP defines a dynamic vehicle envelope (shown at left, from page 95 of this PDF document) that encompasses the range of motion that can be expected from Caltrain's existing diesel fleet, future high-speed trains, and freight trains that use the peninsula corridor.  The dimensions of the dynamic envelope constrain how far from the track center line any future level boarding platforms would have to be set back, in order to prevent what is known as a "platform strike" from a train passing at speed.
  • 8" platforms (existing) are 64" from track center
  • 25" platforms would have to be 67" from track center
  • 30" platforms would have to be 68" from track center
  • 50" platforms would have to be 70" from track center
Meeting the ADA Gap

Unassisted level boarding in Zurich
(Siemens photo)

The vehicle envelope, because it is dynamic, forces a clearance between platforms and trains that is wider than the 3-inch ADA maximum for unassisted boarding.  To provide unassisted boarding without bridge plates, the gap can be bridged automatically by a moving step that extends from the train, a moment before the door opens.  As shown in the photo at right, this step is the key to ADA-compliant unassisted boarding for wheelchair users, and provides a more comfortable boarding interface for bicycles, strollers, luggage, and anything else with wheels.  The step retracts after the doors close, a moment before the train departs.

These gap-filling steps are quite common outside the confines of U.S. commuter rail, and all major vehicle manufacturers worldwide can provide them if the customer asks.  Video examples:
Another common and useful train feature is an automatically leveling suspension, to control the plus or minus 5/8" vertical alignment between the train floor and the platform regardless of passenger load or wheel wear.  A nice bonus of such a system is that it can measure passenger loads in real time.  This too can be provided by vehicle manufacturers if the customer asks.

Caltrain's Approach: What Gap?

Caltrain is now taking a "not to preclude" approach to level boarding, attempting to future-proof the new EMU fleet for any future decision regarding level boarding, pending the outcome of additional planning for the Caltrain / high-speed rail blended system.  This approach is largely a result of not having seriously thought about or planned for level boarding until quite recently.

[Update 6/14/2015: turns out that Caltrain's EMU RFP does require the ADA gap specs for unassisted level boarding!  My source had it wrong.]
As it turns out, Caltrain has no intention to comply with the ADA gap requirement.  Never mind the gap.  As will be apparent in the upcoming vehicle RFP, the new EMU fleet will comply with the ADA using crew-assisted boarding with bridge plates, even after level boarding platforms are built and regardless of the selected platform height.

If Caltrain fails to specify gap-filling steps and leveling suspensions for their new EMU fleet, then wheelchair users will still need crew assistance to board or alight, resulting in random and unpredictable impacts on station dwell times.  Such a failure would preclude reliable and punctual operation of the blended system, increase the amount of timetable padding between trains, and limit the capacity that can be extracted from the peninsula rail corridor before expensive and controversial infrastructure upgrades become unavoidable.  Gap-filling steps and leveling suspensions are perfect examples of small off-the-shelf features that pay off in the long run.

In order "not to preclude" an efficient blended system that extracts the highest capacity from limited infrastructure, Caltrain should require that the new EMU fleet be equipped for ADA-compliant unassisted wheelchair boarding, once new level boarding platforms become available.  Because the new fleet will be in service until the year 2050, this capability cannot be an afterthought and must be engineered into the new trains from the outset.

17 May 2015

CBOSS Headed for Trouble?

The button we may soon have
to press. Photograph by
Sander van der Vel
Caltrain's new Positive Train Control (PTC) system, known as CBOSS, appears to be running into serious technical difficulties just as the program enters its most challenging phase: testing and commissioning.

The system was originally proposed to be built on top of GE Transportation's Interoperable Incremental Train Control System (I-ITCS) technology, an approach that was touted as advantageous for being "off the shelf."  There are subtle signs that things aren't going so well:
  • This month's CBOSS project status update states rather cryptically that the top challenge for the project is GE software release delays.  These delays could be related to the recent purchase of GE's Transportation arm by the French firm Alstom, which already offers a range of PTC technologies that could make the ITCS product line redundant.
  • The technical requirements for the electrification RFP state (see PDF p. 251 of 2,840) that CBOSS is built on Wabtec's Interoperable Electronic Train Management System (I-ETMS), the main competitor to GE's I-ITCS.  Switching from ITCS to ETMS would be like changing the foundation of a house after the roof is completed.
  • Section 4.13.1 of the electrification RFP document describes the electrification project scope, stating that "The Contractor shall provide the signal, train control and grade crossing systems"... a definition of scope that overlaps significantly with the CBOSS project.
  • Section of the electrification RFP document further describes items that are in the scope of the electrification program, including:
    • System-wide track circuit replacement
    • Manufacturing and assembly of signal enclosures, including installation and wiring
    • Installation of signal enclosures, wayside signals, cables, and cable infrastructure
    • Field testing of the signal system and integrated testing with the electrification, EMU, CBOSS/PTC and other interdependent systems
    • All work associated with the modification of the signal system required for the Project, including the CBOSS/PTC system as necessary and as required by all regulatory agencies, including the FRA, MUTCD and CPUC. The Contractor shall ensure that its wayside CBOSS/PTC systems are 100% compatible with the existing CBOSS/PTC systems that its systems will interface with.
  • The electrification RFP document continues for dozens of pages, describing how an almost entirely new signaling system will have to be installed as part of the electrification project.  What CBOSS was supposed to "overlay" will be largely replaced.
Is there a major architectural change in the CBOSS project that Caltrain staff failed to disclose to the board?  The entire CBOSS budget of $231 million (an astronomical sum for just 50 route-miles of railroad) having already been appropriated and mostly spent, are we about to see large cost overruns get squirreled away in the small print of the electrification RFP?  Is the respective scope of the CBOSS and electrification projects sufficiently well delineated to preclude spending money twice on the same item under two separate contracts?

A faint odor of fish wafts over the whole affair.

25 April 2015

The Blue Doors Will Open

Blue doors open at old 8" platforms (shown here)
Yellow doors open at HSR height
There are noises that Caltrain's new EMU fleet might sport a double set of doors, to enable boarding at two different platform heights.  While this isn't necessarily ideal, it is a reasonable solution given the constraints of the problem.  And yet, the prospect of trains with double the usual number of doors elicits gasps of horror from some transit advocates and industry insiders.  Let's go through some frequently asked questions to explore the roots of this choice, and feel free to ask more in the comment section.

Q. Do you intend for every Caltrain platform to be rebuilt?

A. Yes!  Today, the number of Caltrain platforms that support level boarding is zero.  In order to achieve the short and predictable station dwell times necessary to operate the blended system with acceptable reliability, level boarding is an operational imperative for Caltrain. The most important thing to realize is that Caltrain will eventually have to rebuild every single platform system-wide -- if not to the same height as HSR, then to some other significantly greater height for level boarding than the current 8-inch standard.  Level boarding is not just an option; it is a necessary expense without which blending Caltrain and HSR will fail.  Every platform must be rebuilt no matter what; this is the premise from which the rest of the discussion must start.

Q. But why insist on compatibility with HSR platforms?  Caltrain and HSR are separate systems serving separate markets, so why is this compatibility thing such a big deal?

A. Compatibility with high-speed rail is important for two major reasons.

First and most importantly, the San Francisco Transbay Transit Center will be a system-wide bottleneck for both Caltrain and HSR, with just six platform tracks.  This cramped but critically important terminus will be even more constrained if the two operators are forced to use segregated platforms.  In a segregated world, opposing flows of arriving Caltrain and departing HSR could conflict in the station approach tracks, triggering cascading delays should even one train fall behind schedule.  With platform compatibility, any arriving train can be routed to any available platform, minimizing the domino-effect of delays.  The Transbay designers know this issue is the Achilles' heel of the entire design, which is why they are pushing Caltrain and HSR towards compatibility.  The risk of an occasional equipment failure or medical emergency causing a system-wide meltdown depends on the probability of such an incident, combined with the underlying resiliency and flexibility of the infrastructure.  A segregated Transbay design is asking for trouble when things don't quite go according to plan.

Secondly, compatibility has enormous cost advantages for sharing station infrastructure, as will be seen below.  The savings from sharing station infrastructure at just four locations along the peninsula (Transbay, Millbrae, Redwood City and San Jose) could easily exceed the combined cost of converting Caltrain to high platforms system-wide.

Compatible platforms if operated carefully will not interfere with HSR security or fare collection methods.  They are solely a means to maximize the utility and robustness of the Transbay Transit Center and to reduce the capital costs of building California's HSR system by about a billion dollars (yes, with a 'B').

Q. Why can't HSR just select a train design with low floors?

A. It's not that easy.  The CHSRA has expressed an understandable preference for service-proven designs, to draw from the widest range of suppliers worldwide.  Very-high-speed trains (VHST) capable of speeds greater than 200 mph typically do not have low floors.  Nearly all high-speed train designs from Europe, Japan and China for the past several decades have featured high floors, with  few exceptions.  To achieve level boarding as mandated by the ADA while still drawing from the greatest possible selection of vendors, high platforms are almost a necessity for California's HSR system.  The only 200+ mph train with a "low" 30-inch floor is the Talgo AVRIL prototype, still in development.  It does not have distributed traction, which will be important in California's mountainous terrain.

The three foregoing questions allow Caltrain's entire range of possible solutions to be encapsulated in one simple flow chart:

Notice that ALL the level boarding solutions require dual level boarding, at the 8" legacy platform height and at whatever new level boarding height is selected.  Dual level boarding is not an easy problem to solve and usually involves some degree of awkward and clunky mechanisms, be they deploying steps, wheelchair lifts, automatic trap doors, or double sets of doors.  Even the supposedly "simple" level boarding scenario at 25" suffers from this complexity, a fact that is either glossed over or completely misunderstood by most advocates of this solution.

Q. So who cares if Transbay is so constrained?  Can't Caltrain just terminate whatever overflow traffic doesn't fit at the 4th and King terminal?

A. Emphatically, No!  Transbay is a key destination that every Caltrain must serve, especially at rush hour.  75% of Caltrain riders are commuting to work, and there are more jobs located within a 1/2 mile radius of the Transbay Transit Center than within a 1/2 mile radius of all other Caltrain stops from 4th and King to Gilroy, combined!  This enormous concentration of jobs in the heart of San Francisco will only increase with the many new office towers going up today.  Terminating even one Caltrain short of this gold mine of ridership would be quite simply counter-productive, a waste of taxpayer money and a failure to meet obvious demand.

Q. Do you understand the enormous effort and cost to do this?

A. It is a large expense, but also a necessary expense.  The cost of raising platforms is not strongly sensitive to height: rebuilding to ~48" is only slightly more expensive than rebuilding to 25", 30", or any other level boarding height.  Rebuilding to the same boarding height as HSR creates an opportunity to have the high-speed rail project defray some of Caltrain's expense for the conversion to level boarding.

The cost of totally rebuilding every platform is generously $10 million per platform, placing Caltrain's system-wide level boarding tab at (very roughly) $10 million/platform x 2 platforms/station x 32 stations = $640 million, less than half of the cost of the modernization project. On the basis of cost per minute of trip time saved, level boarding beats electrification.

Q. Doesn't this whole issue just boil down to a San Francisco Transbay problem that should be solved at San Francisco Transbay?

A. No, this is not just a Transbay issue.  Rebuilding to the same interface as HSR also enables savings of more than a billion dollars where station infrastructure can be shared elsewhere:
  • The massive dual-level elevated station, the six-mile approach viaducts, and the "iconic bridge" in San Jose would no longer be required, with platforms shared at ground level within the existing footprint of the Diridon station.
  • Squeezing a fourth track under the Millbrae station, requiring hundreds of millions of dollars of tunneling expense, would no longer be required.
  • A Redwood City HSR station, configured to provide HSR service to the booming northern end of Silicon Valley, to enable Caltrain to make cross-platform transfers from locals to expresses, and to tie in future Dumbarton Corridor service, would have a much reduced footprint and would more easily fit in the available site.
Factoring in these infrastructure savings, the cost of converting Caltrain to ~48" is actually negative.  It would be unwise not to do it.

Q. Won't rebuilding all the platforms take years and be an operational nightmare?

A. It will take years, but it can happen with relatively little disruption.  Over the past 15 years, Caltrain has rebuilt 37 platforms from the ground up.  Caltrain has a demonstrated track record for planning, funding and executing platform reconstruction projects.  You'll be hard pressed to find anyone who remembers this causing major disruptions.  EMUs with dual height boarding would considerably simplify the logistics of rebuilding platforms, since each station could be rebuilt independently as funding becomes available and as the planning process progresses in each community.

Q. Will Caltrain end up with a mix of high- and low-level boarding platforms, perpetuating this strange dual boarding height situation forever?

A.  No.  The lower set of doors has only one temporary purpose: to enable boarding from 8" platforms during the transition.  All platforms would be rebuilt to ~48", and boarding from the lower level would ultimately be discontinued.  Any remaining 8" platforms would become an impediment to the blended system, because they would introduce longer station dwells with a significant probability of unplanned delay when boarding or alighting persons of reduced mobility.  Making a mess of the timetable will no longer be tolerable, so there will be a strong incentive to finish the job even at minor Caltrain stops to ensure the highest level of punctuality and system reliability.  This makes Caltrain very different from MUNI or some East Coast commuter railroads, where a mix of boarding heights has persisted for decades because there is no operational imperative for 100% level boarding.

Q. Until all platforms are raised, wouldn't accessibility and dwell time be worse than they are today?

A. No.  EMUs with dual sets of doors would board from 8" platforms with the same efficiency as Bombardier cars, with just two steps up from the platform into the lower level of the train.  (Note that trap door designs would not fare nearly as well in this respect!)

Q. Won't dual sets of doors cause passenger confusion and long dwells?

A. Boarding the train will be obvious, based on which doors open.  Alighting requires queuing at the correct door, which can be facilitated by color-coding of the doors, LED displays, and audible messages.  "Next stop, Menlo Park.  The blue doors will open.  (...)  Next stop, Palo Alto.  The yellow doors will open."  Blue and yellow are good contrasting colors that can be distinguished by color-blind passengers.  People aren't stupid, and should someone get confused, the different doors would be within a few steps and within sight of each other so any mistakes would not lead to significant delays.

Q. Won't all these extra doors displace seating areas and reduce Caltrain's seating capacity?

After conversion to level boarding,
blue doors are plugged and replaced with seats
A. Not necessarily.  Caltrain has estimated that dual sets of doors would displace between 78 and 188 seats per train, or roughly 15 to 25% of a train's seating capacity.  This is a temporary situation during the transition to level boarding, and can be mitigated by procuring extra-wide trains with 5-abreast seating and longer 8-car trains to preserve overall seating capacity.  The space lost to extra doors can be used by standees, who do not have many good options on today's Caltrain fleet.  When the platforms are all converted to level boarding, the lower doors can be removed and additional seating can be installed, especially if this feature is designed into the new EMUs from the outset.

In the meantime, to minimize the loss of seating capacity, it would make sense for Caltrain to make seating capacity a selection criterion in the vehicle procurement process.

Q. Wouldn't this create an accessibility problem, in terms of ADA compliance?

A. No.  Just like today, lifts or bridge plates would be required to board persons of reduced mobility from an 8" platform.  There would need to be an in-vehicle wheelchair lift to change levels inside the vehicle, to allow wheelchair users to board and alight at stations with different height platforms, or to avail themselves of an accessible bathroom on the lower level.  This is not a new technology; these off-the-shelf mechanisms are no more complicated than the exterior lifts used on Caltrain's gallery cars.  An example of such a lift can be seen in this video.

Q. Will bicyclists have to navigate interior vehicle steps, potentially while the train is moving?

A. Yes.  These steps could be made wider and shallower (greater tread depth) than anything in today's Caltrain fleet.  The three steps from a 25" lower level to a 48" mid-level floor could be fitted with wheel gutters to allow bicycles to easily roll up or down along the stairs.  This would make the steps far easier to navigate than the four steep steps up from an 8" platform into a 45" gallery car, turning the corner around a pole through a crowd of Giants fans--the scenario that Caltrain bicycle riders are forced to contend with today.  And riders commonly lift, turn and sort their bicycles by destination while the train is moving, so a bit of jostling isn't exactly a new thing for the bike crowd.

Q. Wouldn't trap doors resolve this whole situation with dual doors?

A. No.  Trap doors have numerous flaws, including one fatal flaw: they would preclude Caltrain passing high platforms at speed while still maintaining an ADA-compliant 3-inch gap when stopped at a high platform.  Trains sway from side to side when running at speed, and the alignment between the track and the platform edge isn't perfect; that means the space between the train and the platform needs to be wide enough to prevent platform strikes but narrow enough to comply with ADA rules.  There is currently no rail system in the United States that can do both: there is either a speed limit when passing platforms (e.g. BART) or the gap when stopped is greater than 3 inches (e.g. Northeast Corridor).  Satisfying both constraints (< 3" gap and 100+ mph past platforms) requires a small bridge step to extend from the train when stopped.  This sort of gap filler mechanism is unlikely to be compatible with a trap door configuration.  Trap doors have other disadvantages, such as increased dwell times while the trap door mechanism is moving, sensitivity to damage from dirt buildup and foreign objects commonly found on train floors, and too many steps up from a low platform during the transition period.

The Takeaway
  • Level boarding is not just an option; it is an operational imperative for the blended system.  The blended system will not work reliably without it.
  • The new EMU vehicles must enable Caltrain's transition to level boarding, or the chance to convert to level boarding will be lost for another 30+ years, the life span of the new train fleet.
  • It is appropriate for Caltrain to adopt the same platform height and width as HSR, in exchange for the funding to achieve the transition to level boarding.
  • Transitioning to level boarding is complicated regardless of the chosen platform height; there is no easy solution.
  • Dual doors are the path to level boarding with the fewest flaws, under the imposed constraint of high-platform HSR.