Among the things on your mind as you step across the platform gap to board a train, the height of the platform above the rails probably ranks last. As it turns out, this dimension--and correspondingly, the floor height of the train--is very important. It determines:
- platform dwell times, or how long it takes passengers to get on and off;
- interoperability between two train systems, Caltrain and HSR;
- accessibility for the disabled and people carrying bulky items (luggage, strollers, bicycles);
- the available options for procuring affordable, off-the-shelf train designs.
The Americans with Disabilities Act
(ADA) mandates that all new rail vehicles and platforms provide level boarding, with the height of the train floor within 5/8" (16 mm) of the height of the platform, a tight specification that is quite difficult to achieve in everyday practice. The grand staircase
that greets most Caltrain passengers will no longer be allowed because the ADA requires "the most integrated setting reasonably achievable
." Caltrain got by until now by using a hodge-podge of grandfather clauses and band-aid solutions
allowed under ADA law, but as the system transforms from an old-style diesel commuter railroad to a modern, fast and frequent transit system, level boarding and full accessibility is no longer a negotiable feature. Indeed, level boarding features prominently among the goals of Project 2025
, Caltrain's blueprint for reinventing the peninsula commute.
That does leave the question unanswered: exactly which height is appropriate for this level boarding to take place? As we will see, this question has far-reaching implications for the peninsula corridor.Caltrain's Plan
Caltrain has for many years harbored the desire, if not the financial means, to operate swift electric multiple unit (EMU) trains
. These trains would increase service speed and frequency, especially at those stations that saw service cut back to make room for Baby Bullet service.
Going back many years, Caltrain's studies invariably conclude that such EMUs should necessarily have two levels (an upstairs and a downstairs), much like Caltrain's existing fleet. The reasons have to do with providing a certain passenger capacity under a cost trade-off between service frequency and train capacity, fitting within platform and train length limitations, taking full advantage of the ample vertical clearances that are available... and last but not least, perhaps also the sheer Strength Of An Idea
Caltrain wishes to procure its new trains on the global marketplace. A sampling of various European bi-level EMUs under consideration, with corresponding entry floor heights:
- France - Alstom Coradia Duplex: 600 - 645 mm (24 - 25")
- Germany - Siemens Desiro: 600 mm (24")
- Switzerland - Stadler Dosto: 570 mm (22")
For reasons related to vehicle packaging (fitting all the train's innards, systems and amenities around the passenger space), as well as historical European platform standards, these double-deck EMUs typically have entry doors and vestibules on the lower deck, with a floor height of 570 - 645 mm (22" to 25")
. High-platform EMU designs are less common, although they do exist in Paris
While HSR on the peninsula corridor has long been a dream, the increasing tempo of events (Proposition 1A, the federal stimulus, environmental planning for the San Francisco - San Jose HST project) has made it increasingly likely that Caltrain commuter trains will mingle on the peninsula corridor with a steady flow of long-distance high speed trains linking the region to the rest of California. Caltrain and the California High Speed Rail Authority (CHSRA) have signed a memorandum of understanding
establishing a broad framework for sharing the peninsula corridor, which envisions "mixed traffic from Caltrain commuter rail and the high speed train service capable of operation on all tracks.
The MOU identifies the urgent need for a systems engineering integration plan, a detailed technical framework for how Caltrain and HSR will mesh together. Importantly, this plan will have to address the issue of level boarding, and whether "mixed traffic" also applies to platform tracks.
The global HSR marketplace, from which the CHSRA will procure its trains, clearly tends toward so-called "high floors" about four feet above the rails: the floor of the rail car's entry vestibule is built high enough to fit the train's wheels underneath. A sampling of various HSR makes and models, with entry floor heights:
HSR will quite naturally gravitate towards high platforms.Regulatory Considerations
Platform heights in California are governed by the federal Department of Transportation
and the California Public Utilities Commission
. There are many laws on the books, and yet more undergoing approval. Taken together, they form a complicated regulatory thicket that has previously, and probably will again, produce odd solutions. The key regulations that govern platform height include the following:
- Platforms must be within 5/8" of the height of the train floor (36CFR1192.175 and 36CFR1192.93) for level boarding
- HSR trains must use high-platform level boarding (36CFR1192.175), typically understood as about four feet floor height
- Commuter platforms must provide full-length level boarding (DOT guidance)
- There may not be steps down into a train (DOT guidance)
- Commuter platforms may not exceed 8" above top-of-rail (CPUC General Order 26) to provide clearance for freight trains.
- New commuter cars must have a 15" floor height for compatibility with Amtrak (see proposed change to 49CFR37.85, effectively already law)
Now it gets really confusing.
These regulations not only contradict each other, but also lead to the strange notion that HSR and commuter rail are inherently incompatible and must therefore be built to differing platform heights. Regardless of this legal mish-mash, it is unlikely that the CHSRA will choose a platform height with Caltrain compatibility in mind; they will choose whatever suits the high speed rail system. That leaves Caltrain to follow their example... or not.
One can easily see where this is all headed, based on the figure at left: with bi-level EMUs, Caltrain is likely to end up with an entry floor height in the low twenty inches, while HSR will end up in the forties. The non-negotiable requirement for level boarding would result in two different and incompatible platform heights. Does that even make sense?The Consequences of Platform Incompatibility
If one considers the peninsula corridor as a transportation system
rather than two independent services simply sharing a right of way, platform compatibility emerges as a key enabler for realizing the potential synergy between HSR and Caltrain, with one serving as a feeder for the other. HSR can operate as a Flight-Level Zero airline with enormous parking garages and rental car facilities, or it can be deeply integrated into an efficient network
of transportation where riding the train to your destination anywhere on the peninsula corridor is not only possible, but convenient and desirable.
One of the greatest opportunities currently facing rail planners is the provision of cross-platform transfers between Caltrain local and express trains. Under this operational concept, a local and an express show up simultaneously, on opposite sides of the same platform
, and exchange passengers. In effect, the express overtakes the slower local at the platform, rather than somewhere between stations, allowing passengers to switch conveniently from one to the other. Such exchanges, operating on regular clock face schedules, would enable fast and frequent service to and from all the stations currently under-served by Caltrain, such as Belmont, Burlingame or San Antonio, and would greatly magnify the utility and efficiency of Caltrain as a feeder to peninsula HSR stops. Caltrain to Caltrain cross-platform transfers, the key to this highly desirable operational concept, inherently require the same boarding height
on both sides of the platform as shown in the figure at right.
Proceeding with two incompatible platform heights would have the following negative impacts:
The Transition Conundrum
- A cross-platform coordinated transfer between local and express commuter trains would be precluded at peninsula HSR stops, unless additional platforms were built. As shown in the figure under Option B, the two key transfer points on the peninsula corridor (Millbrae and Palo Alto / Redwood City) would preclude cross-platform transfers precisely where they are most needed, permanently crippling Caltrain's development potential.
- If cross-platform Caltrain transfers were nevertheless implemented at the Millbrae and Palo Alto HSR stops, these large stations would have to be further expanded with additional platforms (shown in the figure under Option C) and up to six tracks (if HSR infrastructure were completely secured). Such enormous stations, approaching the size of an aircraft carrier, would be out of scale with the surrounding community.
- San Francisco's Transbay Transit Center would be operated as two independent mini-terminals, with four HSR platform tracks and two Caltrain platform tracks. The loss of redundancy from the inability to assign any train to any platform would (a) exacerbate traffic jams in the station approach (by limiting the available paths and thus curtailing terminal capacity); (b) allow small incidents that delay a train (e.g. a medical emergency or law enforcement activity) to propagate to other trains; and (c) prevent spare capacity (unused platform tracks) from being re-allocated between Caltrain and HSR in response to actual travel demand, as opposed to ridership projections made decades into the future.
- The resulting inability of the Transbay Transit Center to support a full Caltrain rush-hour schedule would require the existing station at 4th & King streets to be retained indefinitely, thus confusing commuters, contradicting San Francisco's 1999 Proposition H, and occupying many acres of land that would be more usefully developed for other purposes.
- The San Jose train station, already planned as a massive double-deck structure, would require dedicated tracks and platforms for each service. With compatible platforms, it is likely that a single-deck configuration could meet the various needs of Caltrain, HSR, ACE and Amtrak.
- Under delayed or otherwise unusual traffic conditions, high speed trains could not stop at a Caltrain platform to discharge passengers.
If a common, compatible platform height specification for both Caltrain and HSR is the desired outcome, how do we get from here to there? One of the key requirements for the development of the peninsula rail corridor is to do so without interrupting Caltrain service, to avoid dumping another 20,000 cars on congested roads. Furthermore, changing the height of station platforms, or procuring and commissioning new trains, are not done at the flip of a switch: each would last many months. Under those conditions, converting Caltrain to a different boarding height will be tantamount to changing the wing of an airplane... while in flight. That's not to say it is impossible, but it will require some very creative solutions from Caltrain, an issue that we will revisit later.
In the meantime, now
would be a fine time for Caltrain to initiate the waiver process for GO-26D
, since it is sure to encounter stiff opposition and delay from certain entrenched interests.