Future EMU

The newest automobiles are shown in Paris, Tokyo and Detroit. The latest aircraft are shown at Farnborough and Le Bourget. What about the newest passenger trains? That show, in Berlin, is known as Innotrans and provides a window on the latest evolution in the type of EMU (electric multiple unit) trains that Caltrain is pursuing. One of the future train concepts shown at the recently-concluded Innotrans 2010 is Bombardier's Omneo product platform, ordered in large quantities by French regional transportation authorities and due to enter service in mid-2013. That order is in itself noteworthy, because Bombardier beat French firm Alstom, the incumbent provider of the previous generation of double-deck regional trains, on its home turf.


Tailored slightly for U.S. dimensions, a possible Caltrain Omneo concept is shown in the sketch above. The following key features set it apart from the 1990s-vintage EMUs that feature in Caltrain's electrification plans--the very EMUs that the Omneo is set to replace:

• Articulated design. The wheels are placed between, rather than under each train car, leading to a smoother ride. Gangways between cars, traditionally cramped, dark, loud, shaky and unwelcoming places, are transformed into full-width, seamless passages that turn the train into one continuous space. Vehicle systems (traction equipment, air conditioning, etc. shown in dark gray in the figure) are moved entirely out of passenger spaces, below the floor and above the ceiling. With inter-car gangways and systems cabinets gone, open sight lines promote a sense of space and safety inside the train.
  
  
• A usable amount of high-floor space. Bi-level EMU cars are always a configuration challenge, since passenger spaces must fit around numerous vehicle systems while still providing full ADA accessibility. Accessibility means that wheelchair spaces, bike spaces and accessible toilets must all be provided on the door entry level. Traditional bi-level cars do not provide sufficient room for all these amenities in the high-floor vestibule areas over the wheels, and thus typically board on the lower level where more contiguous space is available. Articulation gets rid of this design constraint.
  
  
• High-level boarding. While the traditional bi-level EMU architecture tends to allow boarding only on the lower floor, this concept features a 1220 mm (48 inch) boarding height that would be compatible with high-speed rail platforms. The Omneo is offered in 550 mm, 760 mm and 920 mm boarding heights, but additional vertical clearance available in the U.S. makes a 1220 mm floor height feasible. A shared platform interface between Caltrain and HSR presents enormous operational advantages by allowing any train to access any platform, especially at San Francisco Transbay.
  
  
• Dual, High-Low Doors. To allow a gradual transition from today's 8-inch platforms to 48-inch HSR-compatible platforms, each vestibule features two doors, one for each height. While this temporarily restricts door capacity during the transition period, the modular door assemblies provide for easy reconfiguration to 100% high platforms once the transition is complete. Dual height doors are not unprecedented.
  
  
• Extra wide interiors. The articulated design shortens car bodies from the traditional 26 m (85 feet) to just 10 or 15 meters. Shorter cars, for a given loading gauge, can be made wider than longer cars. A U.S. spec Omneo car body could be 3.1 m (122 inches) wide in the 15-meter double deck section, and 3.15 m (124 inches) wide in the 10-meter single deck section, all within AAR Plate F. That's 4 and 6 inches wider, respectively, than today's Bombardier bi-level cars used in Baby Bullet service. Such wide interiors might enable comfortable 5-abreast seating.
  

Bombardier vs. Bombardier

It's instructive to compare the Omneo EMU concept to another product in Bombardier's portfolio, the bi-level commuter cars that Caltrain operates for its Baby Bullet service. The diagram at right shows a direct comparison of a Caltrain car to a pair of Omneo cars of roughly equivalent length.

At three seats abreast, an 11-unit Omneo train measuring 145 m (475 ft, a bit shorter than a 493 ft Baby Bullet train) accommodates 695 seats and 48 bikes, compared to 674 seats and 48 bikes for a Baby Bullet. With a two-abreast seating plan making use of the extra width for aisles and standees, the Omneo would still accommodate 590 seats (not counting 48 flip-down seats.) Using a metric that Caltrain is fond of, seats per unit length of train, here's how it stacks up:

• Baby Bullet: 1.37 seats/ft or 4.5 seats/m (including locomotive)
  
• Omneo 3+2 seating: 1.46 seats/ft or 4.8 seats/m
• Omneo 2+2 seating: 1.24 seats/ft or 4.1 seats/m
  

These figures show that an Omneo-like EMU would achieve rough parity with the Baby Bullet in terms of seating density. Of course, as we've discussed before, it's not all about seats... standees are passengers too, if you give them somewhere comfortable to stand.

Innovative Design Enables Platform Height Compatibility

This article is not intended as an endorsement of Bombardier's products; their Omneo train merely serves as an illustrative example. Other manufacturers (Alstom, Siemens and Stadler) aren't standing still, and are also increasingly focused on articulated EMU designs with innovative and flexible interior packaging. In light of these new technological developments, Caltrain's relentless pursuit of 20-year-old double-deck EMU designs locked into a low-platform architecture seems downright archaic.

Cutting-edge European vehicle designs will not compromise the basis of Caltrain's FRA waiver, and might help achieve one of the key tenets of compatibility: a common platform interface for HSR and Caltrain, without billions of dollars and years of platform reconstruction up front. The trains can come now, as part of the electrification project, and the rest can follow later as time and money allows. What is required is a little bit of forward thinking to future-proof the system and enable any train to use any track to access any platform.