10 September 2014

Compatibility, Done Backwards

Steps from an 8-inch platform
into a Bombardier bilevel car
with a 25-inch floor.  The first
step is 10", the second 7"

Caltrain justifies its desire to procure a new EMU fleet with 25" floor height thus:
With a 25” floor threshold, the new fleet will still be compatible with the existing fleet and platforms and could transition to level boarding over time.
"Existing fleet" in this context means the Bombardier bi-level cars, known to the layperson as the red Baby Bullet cars.  Caltrain plans to keep these cars for a few years after the new EMUs arrive.  The Bombardiers already have a floor height of 25" above the rail, although  existing 8" platforms currently require two steps up, as seen in the photo at right.

The statement above sounds like a genuine interest in compatibility, and at first reading seem to make sense.  But let's analyze Caltrain's ideas about compatibility more closely.

Compatibility with Existing Fleet

Suppose for a moment that we planned to "transition to level boarding over time" at 25 inches, because we think it's smart to match the floor level of the Bombardier cars so that we can keep using them after the conversion to level boarding.  Is that even a feasible scenario?

The "before" and "after" cases are straightforward.  Before transition is just the way things are today.  After transition is complete, the entry steps are easily modified to match the interior floor height, achieving gap-free level boarding just like this photo of Utah FrontRunner Bombardier cars docked at 25-inch platforms.

It's the "during" case where things fall apart: because the step modification involves a one-time visit to the shop, there is no way for a Bombardier train (or any other train in Caltrain's existing fleet!) to serve an evolving mix of high and low platforms in daily service during the "transition to level boarding over time".  There would be a 7-inch deep, foot-wide trough between the platform and the car floor that would qualify as a serious tripping hazard even for an able-bodied passenger.  This configuration would be illegal under a number of federal regulations.  The Bombardier fleet would have reduced utility for the duration of the transition to level boarding, likely to be several years.  So let's say it again:

Bombardier cars cannot serve an evolving mix of 8" and 25" platforms during a transition to level boarding over time.

Once the transition to level boarding is complete, maybe in the mid-2030s, the Bombardier cars will be at the end of their useful life.  Given the limited remaining lifetime of the Bombardier cars, their inflexibility during transition, and their dwindling residual value, there is little value in matching the new level boarding platform height to the Bombardier cars.  There may even be negative value in doing so.

Compatibility with Existing Platforms

Mini-high platform built on top of
8-inch platform.  The top of the
mini-high is at 22 inches ATOR.
This is primarily an issue of wheelchair boarding.  Matching the new EMUs to the 25-inch floor height of Bombardier cars allows Caltrain to procure EMUs without vehicle-borne wheelchair lifts, which are expensive to purchase and maintain.  Instead, the EMUs would re-use the existing mini-high platforms to perform wheelchair boarding, using a bridge plate to span the large gap between the mini-high platform and the train.  (Recall this ~3-foot gap is present in the first place because of a California PUC regulation on side clearances for freight trains).

To ensure that a wheelchair user can safely navigate across the bridge plate, its maximum slope is set by ADA law under 49 CFR 38.95 as follows:
  • 1-in-4 for a height change of less than 3 inches from platform to train
  • 1-in-6 for a height change between 3 and 6 inches
  • 1-in-8 for a height change between 6 and 9 inches
  • 1-in-12 (similar to building wheelchair ramps) for a height change greater than 9 inches
Suppose for a moment that we planned to buy EMUs that have to make use of the existing mini-high platforms, which are built 22 inches above the rail and set back 8 feet from the track center line.  What we have is a geometry problem: the ADA slope regulations constrain the vehicle floor height that is reachable from the existing mini-high platforms.  The maximum reachable height is about 27 inches, which (after accounting for a bit of margin) may explain Caltrain's fixation on 25 inches.

But then consider also: each mini-high platform is worth (generously) about $150k to replace.  On a system with 27 stations, 54 mini-high platforms will cost about $8 million to replace.  While that sounds like a lot of money ("Eight Million Dollars!") this sum is a pittance on the scale of the investments being contemplated.  Eight million dollars is two percent of the cost of the new EMU fleet, and less than a percent of the cost of the electrification project.  Put simply, the mini-high platforms have insignificant value and are a trifle to replace.  Designing Caltrain's future around them is certainly penny wise, but quite possibly pound foolish.

Thinking Inside the Box

While Caltrain is no doubt very attached to its growing collection of mini-high platforms and its expanding Bombardier fleet, neither of these items should drive the design of the future platform interface for level boarding.  25 inches is a fine platform height, but selecting it on the basis of these two perceived "constraints" could prove very unwise in the long run.

Caltrain appears to have an uncomfortable relationship with the level boarding issue: it's a distraction from their current big project to electrify the railroad, it's logistically far more challenging to plan for than just stringing up some wire, it involves fighting clearance regulations that are dear to the freight railroads, it isn't funded, and they'd rather not think about it right now because the issue gives them a headache.

But what sort of modernization is this if level boarding becomes a careless afterthought?

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?

04 June 2014

The Great Platform Construction Extravaganza

Redwood City in August 2000
One of the arguments against level boarding is that it would involve a massive reconstruction of just about every single station platform along the entire peninsula rail corridor without interrupting rail service.  On the face of it, that sounds like a very expensive logistical challenge, simply too hard to take on with all the other modernization efforts currently underway.

Would you believe that Caltrain has already done it?  Over the last 15 years, no fewer than 37 station platforms have been built from the ground up.

Following Caltrain's forward-thinking strategic plan, these new platforms were all built for future compatibility with level boarding rolling stock, after a hard-fought waiver of CPUC General Order 26D.  This regulation had previously limited platform heights to 8 inches, causing lengthy station dwells and slowing Caltrain trip times, which thankfully have improved by several minutes over the last decade.

Um, never mind, scratch that entire last paragraph!  All of these new platforms will have to be re-built all over again to achieve level boarding.

Station Qty Opening Cost Comments
Bayshore 2 Mar 2004
San Bruno 2 Apr 2014 part of grade separation project
Millbrae 3 Jun 2003 part of BART to SFO project
Burlingame 2 Jun 2008 $20.5M
San Mateo 2 Sep 2000
Hayward Park 2 Nov 1999
built for future third track
Hillsdale 1 Oct 2005 $2+M new northbound only, with southbound improvements
Belmont 1 Oct 1999 part of grade separation project
San Carlos 2 Oct 1999 part of grade separation project
Redwood City 2 4Q 2000
Menlo Park 2 Aug 2000 $3.3M
Palo Alto 2 Feb 2009 $35M (cost shared with Cal Ave)
California Ave 2 Feb 2009 $35M (cost shared with Palo Alto)
San Antonio 2 Apr 1999
Mountain View 2 Dec 1999
Sunnyvale 2 May 2003
Lawrence 2 Mar 2004
Santa Clara 2 Dec 2011 $40M (cost shared with San Jose)
San Jose 2 4Q 2012 $40M (cost shared with Santa Clara)

Caltrain has demonstrated that they know how to build a large number of new platforms over a time span of a decade or so, which is why it's particularly important that the new EMU rolling stock (which will last three decades) be pre-configured for a future level boarding platform interface.  It would truly be a shame if an effective level boarding solution--fully compatible with high-speed rail--were to be precluded through bad procurement choices made today in 2014.

Here's hoping that Caltrain's 2014 strategic plan will reflect a new vision for level boarding and a new understanding of its advantages for reducing trip times, improving service punctuality, increasing train average speeds, and increasing the overall throughput capacity of the peninsula rail corridor.

03 June 2014

An Enduring Photoshop Job

Way back in October of the year 2000, I was dismayed to find no good renderings of what an electrified Caltrain might look like.  In those days, before copyright became a huge deal, I pointed my Netscape browser to the European Railway Server and grabbed an unremarkable photo of an Alstom EMU taken by Benoît Géhant at Hellemmes, France back in 1998:

Original photo
The next several hours were spent in Photoshop, adjusting hues and pixels, moving doors around, adding more train cars, pasting in a background of the TOD condos at Caltrain's San Antonio station, and "Americanizing" this Gallic EMU with some number boards, grab irons, and a five-chime railroad horn.  The result was this:

After Photoshop
Over the years since, this Photoshop job has found its way into all sorts of places, from newsletters to websites to business plans and countless documents across many agencies and groups involved in modernizing the peninsula corridor.  I even spotted a framed copy at the Station Café in San Carlos, among hundreds of railroad photos from all over the world.  I'm glad it took off like this, and I wish to give Benoît belated credit for the original photo.

25 May 2014

High Voltage Rulemaking Update

Caltrain mascot?
(photo by wwarby)

Feathers are really starting to fly in the Public Utilities Commission proceeding to establish a regulatory framework for 25 kV railroad electrification in California, under CPUC docket number R1303009.  Electric utilities and freight railroads are putting up a big fight against the California High-Speed Rail Authority that threatens to leave Caltrain hanging out to dry.

With the impending electrification of the peninsula corridor clearly in mind, the freight railroads asserted in January comments that "it remains unclear if the proposed rules will be sufficient for high-speed train operation in shared rights-of-way” and that “[i]f the CHSRA does not amend its petition to clearly state the intended scope of the rulemaking, the Commission should order further workshops to ensure that the proposed rules are carefully vetted out for application in shared rights-of-way."

Freight railroads are concerned about a number of compatibility issues, including electromagnetic interference with their signaling systems and vertical clearance for their freight cars.  Electrification could impair vertical clearances especially under bridges.

The CHSRA's response, filed in late March, was crystal clear:
The purpose of these rules is to establish uniform safety requirements governing the design, construction, operation and maintenance of 25 kV ac (alternating current) Railroad Electrification Overhead Contact Systems (OCS) constructed in the State of California in right-of-ways dedicated solely to passenger use with no public highway-rail grade crossings and in which freight operations do not occur.


[The freight railroads] know that the proposed General Order is not ambiguous and that it will not apply to track where freight operations occur. Their continuing refusal to be satisfied on this point reveals a desire to delay and obstruct this proceeding.
The peninsula corridor, of course, meets none of these criteria.  It is not dedicated solely to passenger use.  It has numerous highway-rail grade crossings.  Freight operations occur daily.  The freight railroads are understandably worried about this issue of scope, given that the legislature has allocated more than a half-billion dollars of HSR funding to electrifying the peninsula corridor; Caltrain plans to complete the electrification project in just five years.

Where does that leave Caltrain?
  1. No regulatory framework exists for Caltrain's electrification project
  2. CHSRA is explicitly not planning to establish such a framework
  3. The freight railroads are vigorously opposed to the idea
  4. Time is running out
That leaves Caltrain with few options.

The Short Line Option

It has been suggested that the rulemaking process would be less contentious if a smaller "short-line" freight operator were to buy the trackage rights UPRR enjoys on the peninsula corridor.  Presumably, such a short-line operator would be less adversarial in the negotiation of a mutually agreeable regulatory framework and technical solution for electrification.

This scenario unfortunately fails to take into consideration the precedent-setting nature of placing 25 kV electrification over any track where freight operations occur, regardless of ownership.  The big freight railroads, UPRR and BNSF, will be no less interested in such a proceeding at the CPUC than if their own tracks were being electrified.

The Nuclear Option

Section 8.3.c of the trackage rights agreement with UPRR specifically allows for the wholesale abandonment of freight service on the peninsula, should Caltrain "demonstrate a reasonably certain need to commence construction on all or substantially all of the length of the Joint Facilities of a transportation system that is a significant change in the method of delivery of Commuter Service which would be incompatible with Freight Service."  While 25 kV electrification over freight trains doesn't seem to be such a big deal on the East Coast or the rest of the world, the freight railroads' arguments in the latest CPUC proceedings could be construed as a belief that 25 kV electrification is fundamentally incompatible with freight operations in California.  Do we really want to go there?

Whatever option is pursued, there is little doubt that the freight railroads will have a big hand in the outcome, and that lawyers and judges will be involved.  The freight railroads have clearly demonstrated that they have:
  • Intimate familiarity with the intricacies of the CPUC rulemaking process
  • Ready access to a deep bench of experts who can testify on any technical subject
  • An army of well-paid lawyers
Caltrain will bring a knife to a gunfight if they don't get their act together soon.