Exhibit A: the Electric Multiple Unit conformed contract documents specify that the new level boarding platform height will be 50 inches:
Section 2.2.1.1 Future Level Boarding
CHSRA trains will run over the same alignment and stop at some of the same stations as JPB trains. The bi-level EMU must therefore have the same interface with the infrastructure as the future High Speed Rail cars, including clearance envelope, and platform boarding height.
JPB plans to raise platform heights to approximately 50.5-50.75” ATOR (to interface with a vehicle threshold height of 51” ATOR), initially at San Francisco, Millbrae, and San Jose stations. Other station platforms on the JPB system may ultimately be raised to the same level. These requirements will likely require two sets of doors – one at high level and one at a lower level.
(...)
To facilitate the scenario where all platforms are raised to the ~50.5” ATOR level, it must be possible for JPB to easily de-activate the lower level doors and add additional passenger seating in the lower level vestibule area.
Section 3.3.3 Threshold Height / Platform Interface
EMUs shall be compatible with JPB’s existing platform height (8 inches ATOR) and existing mini-highs (22 inches ATOR). In addition, EMUs must be compatible with JPB’s future level boarding platform height of approximately 50.5 to 50.75 inches ATOR. Each car shall be capable of serving both platform heights during the transition from the existing platform height to the future platform height.
Exhibit B: slides from a November 22, 2016 study session of the Mountain View Transit Center master plan, held to solicit input from the city council. In this document, we find out on page 14 that Caltrain plans to adopt a new level boarding platform height of 25 inches:
Design platforms for future level boarding operations, which will begin after the Caltrain fleet is converted from diesel to electric trains. Level boarding at a 25” height (versus the current 8” height) will shorten boarding time for all passengers and meet Americans with Disabilities Act requirements.
Exhibit C: slides from an October 18, 2016 meeting of the Citizen Working Group advising San Francisco's RAB (Railyard Alternatives and I-280 Boulevard) feasibility study. On slide 11, we learn that Caltrain plans to adopt not one, but two level boarding platform heights. Platforms at 4th/King will be rebuilt to 25 inches, while platforms at Transbay will be built to 50 inches:
For 4th/King it is likely that Caltrain and HSR will operate at different platform heights
• HSR will operate at 50-inches, Caltrain at 8-inches top of Rail (TOR). Therefore, there will be dedicated platforms for Caltrain and HSR at 4th/King
Caltrain may change height of their platforms at some time to 25-inches from TOR but still will be different than HSR
All platforms at TTC to be constructed at 50-inches. Caltrain will use 2nd set of doors at TTC and utilize any platform/track at TTCThis sort of inconsistency would be amusing if level boarding wasn't the most important modernization step that Caltrain must take after the electrification program is completed... and if the EMUs that Caltrain just ordered from Stadler could actually serve a 25" high platform.
The Stadler EMUs won't work with 25 inch platforms
Barring a contract change order and significant technical modifications, the EMUs as specified by Caltrain and as recently ordered from Stadler will not be capable of boarding or alighting passengers at a 25 inch platform.
First, there's the little issue that the floor height of the lower level of the new EMU was not specified in Caltrain's contractual documents. Stadler went with the standard 22" (550 mm) above the rail, according to their specs. Stepping down from a 25" platform into a 22" rail vehicle is frowned upon by regulators. But leave that aside and imagine the trains actually had a 25" floor level that matched a 25" platform.
Unless every single Caltrain platform were to be raised overnight from 8" to 25", a logistical feat that is exceedingly unlikely to be within Caltrain's financial means or capital project planning ability, the conversion to 25" level boarding will necessarily entail a transition period during which EMUs will serve an evolving mix of 8" and 25" platforms. This has technical implications described in the EMU contract documents:
For compatibility with the existing platform height, vehicles will require an intermediate step between the platform height and the lower level boarding threshold height, at approximately 16 inches ATOR. This intermediate step must be either removable or retractable to support conversion to a high-door-only modification once all JPB platforms have been raised to 50.5 to 50.75”. The vertical face of this intermediate step will be located at approximately 61 inches from car centerline. In addition, a ramp or bridge plate must be provided to interface with JPB’s current mini-high platforms to load wheelchair passengers. The ramp or bridge plate must comply with 49 CFR 38.95. The entire platform interface system must also be usable during the transition from the current platform height to the level boarding platform height.This "intermediate step" is identical to the step arrangement currently found on Caltrain's Bombardier bilevel cars. As long as the intermediate step is present (at 16 inches above top of rail and 61 inches from car center line), here's what the situation looks like at a "level boarding" 25 inch platform, during the transition period:
The end goal must be unassisted level boarding at every station, fully compliant with the ADA gap specification of 49 CFR 38.93(d)(1). Manually operated bridge plates are not okay; conductor-assisted level boarding won't cut it for a punctual and reliable blended system where HSR and Caltrain must share primarily two tracks. This means Caltrain should either drop any talk of 25" platforms, or modify the EMU contract post haste with the same retractable bridge plates at the low doors as will be fitted to the 50" high doors.