Alternatives Analysis Analysis, Part 3

The Supplemental Alternatives Analysis for the peninsula corridor reveals some key engineering choices being made. That tunnels would be taken off the table was never in doubt: tunnels are nothing but trouble. The only tunnels now left are those that have a mountain. Well, almost... as we'll see below.

• Freight grades: we were told all along that 1% is the limiting gradient for heavy freight. Not so in Palo Alto, where there is a 2% grade shown in the track profiles (page 15). Recall that the steepness of a grade has no impact on passenger comfort, frequent references to roller-coasters notwithstanding. (This question of dynamics seems to confuse civil engineers, who deal mostly with statics.) If a freight train can handle a 2% grade in Palo Alto, it can certainly handle a 2% grade anywhere else; that's the concept of ruling grade. Considering that steeper grades would greatly reduce the footprint of any elevated section, for example, the massive Mary Avenue rail overpass in Sunnyvale shown on page 18, why are 2% grades not the rule?
  
  
• Rail yard: the rail yard in Brisbane, the closest-available 100-acre parcel near San Francisco, is on a direct collision course with the redevelopment plans for this area. This may end up as the largest land transaction in the peninsula HSR project. Curiously, the yard is planned on the east side of the tracks, opposite the historical site of the Southern Pacific rail yard.
  
  
• Berms be gone: Belmont and San Carlos get their grade separation berms removed and replaced by a gratuitously tall viaduct, with the tracks 20 feet higher than today's berms. That doesn't go over well with the mayor of Belmont. Prediction: when all's said and done, Belmont and San Carlos will be begging for their berms to stay essentially as they are.
  
  
• Blank-check engineering: Millbrae gets some ridiculously massive civil works in order to shoe-horn a fourth track under the ill-configured station. The plan features a 2.5-mile long tunnel (see track profiles, page 8), diving 75 feet below grade in order to duck under the Hillcrest Blvd underpass. Cross sections are also provided (see pages 13 and 14). There are two design options that are likely to be far cheaper and less disruptive to construct:
  
  
  1. Convert the western-most BART track to Caltrain (see Option D in this diagram). While this requires minor surgery on the existing BART station, and may require an exception to side clearances (e.g. a steel crash barrier to separate BART from Caltrain), no digging would be required.
     
     
  2. Put the Millbrae BART platforms underground. The tunnel already exists, emerging right before the station.
  
  When the alternative is a 2.5-mile tunnel with an underground station mezzanine, which would likely require partial demolition of the existing station structure all in the name of leaving untouched the under-used BART parking tracks, one is left wishing that these issues had been thoroughly examined and addressed in the AA.
  
  
• Slimmer sections: Many cross-sections have gone on a diet, narrowing down from the previous elephantine proportions to more realistic dimensions. The four-track retained-fill berm is slimmed down to 78 feet (wall to wall), the elevated viaduct is down to 78 feet, the trench is down to 76 feet (fence to fence). The at-grade alignment remains at 93 feet (fence to fence), but only because the fences are set back 11 feet from the (perfectly safe-to-touch) overhead catenary masts. The eminent domain panic set off back in March was premature: the tracks will mostly fit within 80 feet, a width already available along 88% of the corridor.
  
  
• Fatter bridges: box-beam elevated structures have a depth of nearly 10 feet (measured from the bottom of the bridge deck to the top of the rails), compared to 5 feet as routinely practiced today, for example on the Belmont - San Carlos grade separations. That means future grade separations must lift the rails at least 25 feet above the road surface, compared to about 20 feet today, with attendant increases in the size of the bridge approaches. Five feet taller, especially when a sound wall will rise another 4 to 8 feet above rail level, makes a huge difference to visual impact.
  
  
• PAMPA sandwich: The finalized application for the next federal funding increment includes a description of the project phasing plan for the peninsula. Phase 1: 4 tracks Redwood City and north + PTC. Phase 2: 4 tracks Mountain View and south + electrification. That leaves Palo Alto - Menlo Park - Atherton (PAMPA) with a two-track at-grade gap, left until such a time as there develops overwhelming pressure to fill it in.
  
  
• VTA buried: The light rail spur in Mountain View is buried under the Stevens Creek, to make room for the expansion of the corridor. That doesn't strike one as the cheapest way to do things.
  
  
• Viaduct vengeance: A FIVE MILE, 60-foot tall viaduct is planned in Santa Clara, an area of the corridor that is (a) already fully grade separated and (b) mostly wider than 100 feet. These people don't do subtle: their vocabulary is reinforced concrete, shoring walls and outrigger bents. This area of primarily commercial and industrial properties is less likely to oppose such a gratuitous structure. Operationally, the HSR viaduct needlessly prevents Caltrain overtakes anywhere between the Santa Clara and Lawrence stations. All pain, no gain... or from their point of view, all profit.

Clearly, there is a long way to go before context-sensitivity is achieved.