While the June schedule does not show any change in the deliverables dates, in July there will be a change in the delivery of the 15% integration package from September 2010 to October 2010 to change the alignment of the Caltrain tracks to the outside and HST tracks to the inside tracks to reduce the footprint at Caltrain station locations (using side rather than center platforms).The good news is that the previously-favored, segregated SSFF or FFSS arrangements seem to be off the table. Those arrangements would have prevented the express overtakes that are the key to an effective Caltrain timetable, and would have forced wrong-way movements whenever any one of four tracks went out of service. Wrong-way movements vastly diminish track capacity and exacerbate cascading delays, where one late train makes a mess of the whole timetable--as any regular Caltrain rider knows all too well. So that's the good news.
The bad news is that Caltrain will be stuck with side platforms. When a Caltrain track goes out of service, as it inevitably will, routing trains to the opposite platform will now require cutting across the HSR tracks, as shown in the diagram at left. No more central island platforms, which have undeniable operational advantages as well as simplified passenger access.
Given the choice between giving up island platforms (SFFS) or giving up overtakes (FFSS / SSFF), then SFFS wins by a mile because overtakes are key--but that's really a false choice, constrained by the menu of alternatives. The one alternative that is seemingly not being given due diligence is FSSF.
Their logic might go like this:
- Caltrain design criteria (Chapter 3, paragraph 1.1.d) and HSR Technical Memo 2.2.4 (Station Platform Geometric Design, section 6.1.3) dictate that platforms must be perfectly straight.
- Straight island platforms require a double-reverse curve "wow" around the platform at every station, conflicting with HSR Technical Memo 2.1.2 (Alignment Design Standards for High-Speed Train Operation, section 6.1) that prohibits more than four so-called direction changes per mile.
- The reverse curve "wow" beyond each end of the island platform consumes an inordinate amount of land precisely where it is most valuable, in the denser suburban cores where train stations tend to be located.
As discussed in Football Island, curved platforms allow the "wow" around the center island platform to be much more compact, using barely any more land than the side platform configuration. The diagram at right (do you see the football?) highlights the difference in green, amounting to about a half acre. With the exceedingly generous clearances likely to be used--the diagram shows a mere 75 feet of right of way width!--the difference would be even less. Now imagine a straight island platform, not shown in the diagram, where the green area would need to bulge out over a far greater length; the extra area would amount to the entire area of the platform, 30 x 750 feet or another half acre. That is indeed a waste of valuable land.
Fast-Slow-Slow-Fast isn't some far-fetched concept. It works in Sweden, and it would work here, far more efficiently and flexibly than a carbon copy of the Northeast Corridor. Why not give a careful second thought to curved platforms, unencumbered by rote compliance with ill-considered specification requirements?