by Rafael
Heads up #1: The Sep 12 teach-in on high speed rail organized by the Peninsula Cities Consortium has been moved to a new location due to high demand. The event is free, but anyone wishing to attend must now register at the above web site due to limited capacity. (h/t Morris Brown)
Heads up #2: The TJPA as about to hold its monthly meeting for the Citizens Advisory Committee. The agenda includes updates on ARRA funding as well as the design of the DTX tunnel and throat. The meeting is open to the general public, but if you're not a member of the CAC and plan to attend, it might be a good idea to call the TJPA at 415.597.4620 (or email info@transbaycenter.org) to check if there will be room for you. Lobbyists may have to register with the city of SF first.
Date: Tue Sep 8
Time: 3:30pm - 7:30pm
Location: TJPA offices, 201 Mission Street (at Beale), Suite 2100, San Francisco, CA, in the Large Conference Room
In my recent post Fear and Loathing in San Jose, I suggested that one alternative to the UPRR/Monterey Hwy corridor would be to cut over to the available 101 median via the also available 280 median. At the time, I thought an underground station and tunnel to east of the 87/280 interchange would be the only possibility.
On closer examination, I now believe a variation of this alignment might just barely be possible above ground, drastically reducing the cost while also avoiding south San Jose neighborhoods entirely. The station would still be at an angle to both Caltrain and BART, but located further north than before. Its supports would have to be positioned such that they don't interfere with the future BART tracks, which will wrap around the HP Pavilion underground en route to the future station and maintenance yard in Santa Clara. They must also avoid conflicts with the underground VTA light rail tracks. That's going to be tight. My drawing reserves about 80 feet of width for the station, that's for two tracks plus extra-generous island or side platform(s). There is no need for more than two HSR tracks at San Jose Diridon.
View SJ Diridon: HSR above ground, south via 280/101 in a larger map
The alignment would parallel UPRR's via an aerial above Montgomery St. (with double glazing sound walls) and veer east onto I-280 at the Auzerais Ave intersection. It would reach that median just west of the 87/280 interchange via a tight curve (~1000 ft radius). There is ~1600ft of run length between the Bird Ave westbound off-ramp (which trains must fly over) and the overpass from 280 east onto 87 north (which trains should pass under). At 3.5% gradient, that distance may be just enough to achieve the required elevation change of ~50 feet, factoring in the need for vertical transition curves at either end.
The curve at the 101/280 interchange is just as tight and just as gnarly. Trains would have to pass under the tall southbound overpass turnoff from 680 south onto 101 south and then immediately climb at 3.5% so they can pass over Story Rd. Again, I'm threading the needle here.
In both cases, the small curve radius coupled with the steep gradient means the achievable speeds will be quite low: assuming 5" track cant plus 7" cant deficiency, the maximum permissible speed on a curve with 1000ft radius is just 55mph. Note that current FRA rules limit track cant to just 3" but that's based on the assumption the track will be used for heavy freight trains, which is not the case here.
Since most trains will be stopping at SJ Diridon anyhow, that's primarily an issue for the SF-LA non-stop line haul time: combined with the additional 2 miles, this alignment would add 2-3 minutes. The exact penalty depends on technically feasible speeds in the 101 median vs. politically feasible ones in a ROW in the UPRR/Monterey Hwy corridor. There are ways to compensate for the penalty, e.g. straighten some curves further north. AB3034 requires CHSRA to deliver an SF-LA line haul time of 2 hours 40 minutes, which is already quite aggressive.
In south Gilroy, the least disruptive solution would be to follow 101 until it's no longer designated a freeway and then use an aerial to cut across farmland over the UPRR central coast line, twice across hwy 25 and finally across the UPPR spur to Hollister before descending back to grade following the original alignment to Pacheco Pass.
View SJ Diridon: HSR above ground, south via 280/101 in a larger map
Note: CHSRA's alignment for cost estimation purposes included a trench plus tunnel under the Caltrain tracks between San Tomas Expressway in Santa Clara and Julian St. in San Jose. I've shortened that to Taylor St. by swiping the westernmost CEMOF tracks and running at grade there. That's cheeky but Caltrain can almost certainly make do without those tracks. Bellarmine College Prep High School should not be impacted by the change.
In terms of overall cost for SJ - Gilroy, this revised alignment via I-280 and US-101 might actually be cheaper than the one CHSRA has proposed. It avoids running through numerous San Jose neighborhoods, does not rely on purchasing ROW from UPRR, avoids five grade crossings between Diridon station and Bernal Ave, avoids the existing overpass at San Carlos St. and, it avoids many additional grade crossings south of San Jose as well as aerials through the downtown areas of Morgan Hill and Gilroy and that tunnel section under CEMOF. Plus, there won't be any room for a "Grand Central of the West" station with numerous platform tracks. Two with generous platforms will do just fine, it's a through station not a terminal.
