Fear and Loathing in San Jose

by Rafael

We can't stop here. This is bat BART country.

The recent Initial Ruling On Atherton vs. CHSRA highlighted the issue of ROW acquisition, especially if that might involve exercising eminent domain. There's been a lot of speculation about the possible implications for the route out of the Bay Area and even the project as a whole. However, the plain truth is that it's now up to the judge to spell out the remedial actions CHSRA must take to bring the program level of its EIR process for the Bay Area to Central Valley section back into compliance.

One aspect that will surely have to be addressed is the issue of exactly where and how to run dedicated HSR tracks between San Jose Diridon and Gilroy, a topic I'll explore below. First though, let's recap why CHSRA preferred a route that goes through San Jose at all.

Economic Objectives

San Jose likes to bill itself as the "Capital of Silicon Valley", which actually stretches from San Jose all the way up to San Mateo and across to Cupertino. Much of the so-called "Golden Triangle" portion, bordered by US-101, I-880 and CA-237, actually lies in Santa Clara and to a lesser extent, in Milpitas. However, most of Silicon Valley is chock-full of high-tech computer hardware and software companies, ranging from highly innovative startups to global leaders in the computing and internet industries. Along with agriculture and the movie/TV industry, Silicon Valley is a primary economic engine for the state.

Both directly and indirectly, tax revenue from these companies and their workforce will contribute a large fraction of the funding for the California HSR project. Paradoxically, wealth is both why HSR has to serve Silicon Valley and why CHSRA is facing opposition to an alignment with elevated sections in the SF peninsula.

San Jose has about a million residents, making it the country's tenth-largest city. However, a significant fraction of Silicon Valley's highly skilled workforce neither lives nor works within city limits, a situation San Jose's civic leaders would like to change. The General Plan shows the location of these limits and also the city's development pattern. Most of the built-up area is "medium low density residential", though there are some higher-density developments here and there. A sizeable area just south-east of the SJC airport is blighted by aircraft noise and FAA-imposed maximum building heights. It is used by the US Army and for Guadeloupe Park.

The Diridon station lies just west of the flight path and, high-density residential housing has been/is being built just west of it. However, except for Caltrain's CEMOF maintenance facility and the HP Pavilion, long-standing efforts to attract commercial development between the station and CA-87 haven't been as successful. Back lots and at-grade parking lots are plentiful. Caltrain ridership into and out of Diridon station has historically been low for that very reason. In conjunction with the BART extension, HSR is supposed to deliver what Caltrain never could: attract commercial and residential development to the mid-town and downtown areas within approx. 1/2 mile of the station.

Note that neither HSR nor the long-sought BART extension are fully funded at this point and that there's no reason to believe airport blight will abate.

Transit Oriented Development

Nevertheless, San Jose is giving this another try and hosting a visioning workshop for the Diridon station area:

Date: Saturday, Sept. 12, 2009
Time: 9:00-12:00
Location: Parkside Hall, Room B (west of Tech Museum of Innovation), 180 Park Ave

(Note that as reported earlier, the Innovation Place HSR Workshop in Palo Alto will be held on the same day from 9:00am-3:30pm. See also Clem's post Palo Alto Innovates)

Separate plans for transit-oriented development already exist or are in development for Santa Clara, Beryessa, Fremont Warm Springs, Union City and Fremont Centerville (context: Dumbarton Rail + Amtrak CC/ACE). All of these are supposed to boost ridership into the downtown-midtown area of San Jose and, to connect to HSR at Diridon station.

HSR Phase 1: San Francisco, San Jose and Points In-Between

Whether all of these plans for rail transit and transit-oriented development will come to fruition or fail to attract sufficient funding remains to be seen. However, while the wording of AB3034 would technically permit CHSRA to exclude San Jose from phase 1 or even from later phases, any attempt to do so would face massive political opposition on account of the above. Note that the bill, which was the basis of prop 1A(2008), specifically requires the starter line of the HSR network to terminate at the San Francisco Transbay Terminal. Therefore, terminating it San Jose for now as some have proposed would require the state legislators to amend the bill with a 2/3 majority in both houses and probably, a new ballot proposition to approve that amendment. San Francisco would never allow that to happen.

Ergo, for all intents and purposes, both SF and SJ need to be served by HSR in phase 1. The most straightforward way to do that is to leverage the PCJPA's Caltrain ROW and cross over into the Central Valley via Pacheco Pass. Since Caltrain "baby bullet" service takes 57 minutes between these two cities and AB3034 explicitly mandates that express HSR trains do it in just 30, the plan of record is to quad-track the entire ROW, even though narrow ROW sections such as downtown San Mateo present major engineering challenges if eminent domain is to be avoided at all costs. A second complication is that even if FRA gives Caltrain a waiver to operate mixed traffic (new non-compliant electric EMUs + a few legacy diesels for SJ-Gilroy + UPRR freight trains) at up to 79mph, it almost certainly won't give CHSRA the same luxury in the related but separate "rule of special applicability".

So, for both regulatory and capacity reasons, the intent is to upgrade the Caltrain corridor for mostly two tracks to a full four everywhere. Building just HSR tracks in another peninsula corridor, US-101, was considered but rejected due to constructability issues (lack of available medians) and because the corridor doesn't run near the desired stations. Also, this option would have done nothing to fully grade separate and electrify Caltrain, nor could peninsula residents have transferred to long-distance HSR trains at selected stations between SF and SJ.

Approaches into San Jose Diridon

South of San Tomas Expressway in Santa Clara, CHSRA's Google map of the route (please zoom in) shows an expensive trench/tunnel section to just north of SJ Diridon. Presumably, that's just two tracks reserved for HSR, so Caltrain would remain at grade (it's already grade separated in the area). Also note that the HSR tracks need to cross over or under the UPRR tracks somewhere between Santa Clara and Gilroy. Doing so in Santa Clara isn't possible because the BART tracks will run east of UPRR's line as far south as West Santa Clara Street, immediately north of Diridon station. Present plans therefore call for HSR to stay west of the Caltrain tracks. Note that tracks will need to emerge to the surface north of W. Julian St. since that's an existing underpass and tracks need run length to fan out to the platform tracks on the new deck above the Caltrain/UPRR tracks.

CHSRA's plan of record calls for a mix of aerials, embankments and cut/fill sections to cross I-280 and reach Gilroy via the UPRR/Monterey Hwy corridor. In some sections, the UPRR ROW might have to be widened via acquisition of land or air rights from private property owners - via eminent domain if need be. Failure to qualify the risk of such takings was one of the complaints the judge upheld in Atherton vs. CHSRA.

The track fan south of Diridon station can merge west, east or directly above the UPRR tracks, as desired. However, note that W San Carlos St. is currently an overpass. It would have to be converted to an underpass to keep HSR tracks from having to change elevation yet again. However, there's probably a good reason is was built as an overpass to begin with. Also, it's not clear if all of the HSR-related grade separation works shown on CHSRA's Google map are strictly for the new HSR tracks or would also include the legacy tracks used for UPRR freight, Caltrain and Amtrak Coast Starlight. By default, the latter might be preferable, but also much more difficult to construct (shoofly tracks). Given the low total volume of FRA-compliant traffic between San Jose and Gilroy - just 6 freight, 6 Caltrains and 2 Amtrak trains - it may well be acceptable to retain grade crossings for the legacy tracks only.

Since UPRR declined to entertain an offer because of supposed safety concerns, it cannot credibly pretend they've magically gone away even CHSRA were to offer it the moon. At the very least, there would have to be some engineering studies to determine if a given implementation proposed by CHSRA meets UPRR's criteria, which it hasn't even spelled out yet. This could drag on for years even if price were no longer an issue.

Ergo, UPRR's decision not to offer up any of its ROW nor air rights above it south of Lick (Caltrain's Tamien Yard, just north of Almaden Expwy/87) means CHSRA will have to secure land/air rights nearby, if only to avoid delaying the project. This will be tricky to achieve without eminent domain, especially near the gated communities just south of Curtner Ave, which is an overpass. Note that a VTA light rail line runs in the CA-87 and CA-85 medians.

Alternative to the UPRR ROW

However, the medians of both I-280 and US-101 are still available. Freeway medians are usually narrow, possibly limiting the maximum safe speed to below what CHSRA was counting on for a given section of the route. BART trains aren't constrained, but then their top speed is 79mph to begin with. As always the devil is in the details, i.e. exactly how many feet of width are available. Google Map's satellite view doesn't provide that level of precision.

The hardest part would be the section between W Santa Clara St and just east of the gnarly I-280/CA-87 interchange. Overpasses there may not be tall enough to permit HSR trains to run underneath, so it's better to avoid it altogether. In addition, HSR trains are limited to gradients of 3.5% and need generous curve radii at elevated speeds, so an entry point west of the interchange would be ambitious.

A deceptively simple solution would be to keep the HSR tracks underground south of CEMOF all the way to east of the interchange. Once you've bitten the bullet and gone underground, there are advantages to staying there. However, it would also put the SJ station underground, with full-length (1/4mi) platforms placed at an angle relative to those of both Caltrain and BART. There would be no need for architectural Viagra on the surface, not that need ever had anything to do with it to begin with. However, in raw transportation terms, an underground station with as little as two run-through tracks and one large island or two generous side platforms would get the job done. Fortunately, the area is partly parking lots and the aforementioned visioning workshop - a very early stage of the urban planning process - hasn't even happened yet.

There's plenty of room to run west of the BART tracks curving around the HP Pavilion, but the HSR tracks actually need to run sufficiently deep to pass under the VTA light rail line that already crosses under the Caltrain/UPRR tracks. HSR would also need to cross under the Guadeloupe River, a residential district, CA-87 and a second creek before emerging in the I-280 median. Note that the HSR tracks would also need to run either west of or else under the future BART tracks.

In other words, the HSR line and platforms would have to be very deep underground anyhow. Since San Jose is a through station anyhow, perhaps a single extra-wide island or two generous side platforms would actually be sufficient. Trains run past platforms in Europe and Japan at fairly high speed all the time. Waiting passengers are simply warned to retreat to a safe distance via the PA system and markings on the floor. The VTA tracks would prevent a full concourse level, but none is needed anyhow. Multiple pedestrian connections to the surface, to BART, Caltrain and the VTA station would be sufficient. Some of these passages could feature moving walkways to reduce transfer times. ADA compatibility would be achieved via elevators, but ramps or inclined moving walkways are more reliable in case a wheelchair user needs to be evacuated.

At the anyhow pre-blighted I-280/US-101 interchange, the cheapest solution would be a tall aerial to transition between the medians. However, it would have to fly over a descending overpass lane, so it would be a tall structure. Still, the incremental visual and noise impacts should be minor. The alternative would be to execute the transition underground, but that's more expensive.

Optional Extension through Altamont Pass

Tunneling under the I-280/US-101 interchange only makes sense if there is a desire to leverage all the work that was put into reaching the I-280 median for something else: a turnoff to continue east to I-680, whose median is also still available - all the way to the foot of the Sunol grade in Fremont, actually.

If Caltrans is prepared to reserve that median for HSR trains, it could be the basis for a future shortcut to Sacramento via Altamont Pass. Between Scott Creek Rd and E Warren Ave in Fremont Warm Springs, the tracks would veer east and across to Haynes Gulch via a long tunnel under Monument Peak. There, they would veer north, running essentially at grade next to Calaveras Rd. as far as the CA-84/Calaveras Rd exit off I-680. An aerial across the CA-84 and another tunnel would lead the tracks to an intermodal with BART at El Charro Rd in east Pleasanton/west Livermore. It would be heard to avoid impacts on both the nearby ponds and Livermore Municipal Airport, since crossing at grade is not feasible because of UPRR. Altmont Pass would be traversed - except for one short section - via the I-580 median. Passing north of Tracy, tracks would connect to the phase 2 spur to Sacramento near either Manteca or Escalon.

Optional Extension to Walnut Creek

Note that the I-680 median is still available between just north of the CA-84 exits to just south of the CA-24 interchange in Walnut Creek. A tunnel section under California Blvd. would be needed to create an intermodal with the BART station. However, that road features a tight chicane and there is a medical center next to the freeway. Tunnel tracks would have to thread a needle between its buildings. This would require a technical feasibility study as well as the consent of Kaiser Permanente regarding any number of issues, including construction nuisance and vibrations from passing trains. Eminent domain against a hospital is basically unheard of, so I'd consider the whole thing a long shot. However, even without an intermodal with BART, there would at least be HSR service to eastern Alameda and central Contra Costa county.

Maps for Alternative #1

The alternative ROW and extension options are shown on the map below. Switch to satellite mode to see why the HSR station would have to be deep underground. Zoom out in map mode to see the regional implications. Switch to terrain mode to see where there are mountains to contend with.

The picture below the map shows location of major known faults - basically, Calaveras Rd. and I-680 north of Sunol are right on top of the Calaveras fault. The Hayward fault generated the 1868 earthquake, estimated at 6.8 on the Richter scale. Paleoseismologists have estimated the mean time between such events on that particular fault to be 140 years, so statistically, it's due right around now. Perhaps it's not the most auspicious time to build a railroad, but the people of California have never allowed themselves to be paralyzed by a fear of Mother Nature. See our earlier post Shake, Rattle And Roll for more background on earthquake engineering in the railway industry.


View San Jose Diridon: HSR Underground in a larger map

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Alternative #2

Since we're talking hypotheticals anyhow, here is a second alternative based on using 101 between SJ and Gilroy.

To come up with this one, I started in Gilroy and worked my way north. It quickly became apparent that the problem in San Jose could be addressed by simply moving the HSR station to the huge transit-oriented development at Beryessa and continuing north up the East Bay instead of the SF peninsula. CHSRA did study the scenario of SF + Oakland + SJ via Pacheco but not along this particular right of way, which does not depend on UPRR but precludes extending BART south. Moreover, whatever is gained in San Jose is lost (and then some) because the only available unused railroad right of way runs from Union City to just north of Oakland Coliseum. Reaching it from Fremont Irvington with full grade separation requires tunnels in Niles, tiptoeing around the water supply for 100,000 people.

The aforementioned available ROW runs right next to BART, but unfortunately its tracks cross over in three locations. That would greatly complicate the vertical alignment, though at least heavy freight does not impose any gradient constraints.

North of Oakland Coliseum, a few miles of greenfield ROW immediately next to BART would be required, complicated by the Fruitvale station and transit village. A tunnel under the Lake Merritt outflow and 4th Street in Oakland would need to pass under the east portals of the Webster/Posey road tunnels across to Alameda. The upside is an elevated intermodal station with West Oakland BART. Sanity would dictate that HSR terminate here in phase 1, after all downtown SF is just one BART stop away. However, as discussed above, AB3034 mandates a terminus in San Francisco Transbay Terminal. Since the station there is in the basement and the new east span of the Bay Bridge was redesigned specifically not to support the weight of BART/light rail/HSR trains, a second transbay tube would have to be part of the phase 1 specifications. Note that it could not cross the existing tube underwater.

As a result of all this, switching to the East Bay would be no easier than sticking with the peninsula. Multiple hard-fought political decisions would have to be reversed, multiple EIS/EIR processes re-done. Whatever ARRA is available for California HSR would be spent elsewhere in the state.

Summary:

- HSR up 101 from Gilroy ($)
- modest elevated San Jose HSR station at Beryessa TOD ($)
- VTA's WPML ROW used for HSR (priceless ;^)
- tunnel in Niles to reach UC BART (stacked single tracks, $$)
- dedicated HSR alignment next to BART ($$$, ROW incomplete, BART crosses three times)
- tunnel under Oakland's Chinatown ($$$)
- second transbay tube to San Francisco Transbay Terminal Center ($$$$)

Consolation prizes:

- BART extended to Livermore via I-580 ($$)
- Caltrain electrification SF-SJ Diridon ($$)
- VTA light rail subway under E Santa Clara St and up to Beryessa via track stacking on short section of WPML ($$$)

Canceled: BART to Santa Clara (-$$$$)
Canceled: BART maintenance facility in Santa Clara (-$$)
Canceled: widening Caltrain corridor (-$, -litigation-related delays)
Canceled: Dumbarton rail (ROW in Union City usurped by HSR) (-$$)

Shelved indefinitely: DTX tunnel in San Francisco (-$$$)
Pushed back to PCJPA: full grade separation of Caltrain corridor (-$$$)


View HSR up WPML instead of BART in a larger map

Basically, this Alternative #2 was an interesting exercise, but it would really put a pride of lions among the pigeons. The takeaway is that switching to the East Bay would solve some political issues in the mid-peninsula at the expense of a whole new set of headaches.

Alternative #1 is more limited in scope, it "just" completely reconfigures the SJ station and moves the one in Gilroy to the 101 median.

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UPDATE: Alternative #3: Commenter BruceMcF (h/t) has suggested that stacking HSR and VTA light rail tracks in the 87/85 medians between Lick and the Santa Teresa district would be both feasible and cheaper than the alternatives discussed above.

There are multiple existing road overpasses, including Almaden Expressway and Blossom Hill Rd. next to the station there. The stacked tracks would have to fly over those, raising tracks very high. VTA light rail leaves the 87 median and forks tracks at Ohlone Chynoweth station next to the 85/87 interchange. It leaves the 85 median in the Santa Teresa district. Combined with station access issues, this favors stacking the HSR tracks on top of light rail.

However, that puts the (slightly) heavier HSR trains on top and increases noise emissions. HSR's maximum gradient is smaller than the one light rail vehicles can negotiate and, greater vertical transition radii are needed on account of the higher speed. Note that VTA light rail is triple-tracked in some sections and would be down to just two after the project. Separately, note that the 101 median is not available right at the 85/101 interchange but that land for tracks to hug the northbound on-ramp is. At an appropriate point further south, the alignment would cut back over into the median.

Note that VTA's daytime light rail operations would need to continue during the construction period.


View SJ Diridon to Gilroy via UPRR/87/85/101 in a larger map

Transbay Terminal Redux

Heads Up: Neighborhood meeting on HSR for residents of the Willow Glen neighborhood in San Jose, on Wednesday, April 8 at 1292 Minnesota Ave from 7-9pm. Resources at the end of this post.

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The fair city of San Francisco has probably had more than its fair share of coverage on this blog. In just the past couple of months, we've already had quite a few posts recently on the controversial new Transbay Terminal Center (see posts 1, 2, 3). In addition, Clem Tillier has published a post on the Focus On: SF Transbay Transit Center on his Caltrain-HSR Compatibility Blog.

So why revisit this issue yet again? Well, because Quentin Kopp is once again saying that 4th & King would be good enough for him - knowing full well that this will unleash howls of protest from SF city officials and residents, in no small measure because CHSRA consistently marketed the starter line as going from downtown San Francisco to San Jose Diridon, LA Union Station and Anaheim ARTIC.

Note, however, one flaw in the snippet from the Examiner: supporting a five-minute headway on the HSR line down the peninsula is not quite the same thing as actually running a train literally every five minutes. It just means that the signaling and other technology has to cope with an HSR train following another within the space of five minutes, something that may well happen at certain times in a timetable supporting multiple service classes (e.g. express, semi-express, semi-local, local). Recovery from unexpected delays and other off-design conditions may also require operators to minimize headways at certain times. Safe operations of sections of a line with moderate speed limits are possible with as little as 2.5-3 minute headways, so 5 is actually conservative.

The number of platforms is a potential issue a number of decades down the road, maybe. On the other hand, the poor design of the connection between the DTX tunnel and the platforms, the so-called "throat", is a real issue right now because Caltrain will also use the tunnel and downtown station. It's a bottleneck even an expensive three-track tunnel cannot fully resolve. Moreover, according to Clem, the current design of the DTX tunnel features curve radii so small that they effectively preclude the use of Japanese shinkansen train designs for the California system.

Recap

The current design features 6 long platform tracks, some slightly curved, accessed via three-track tunnel out to Caltrain's existing 4th & King terminus station. The six tracks would be accessible via three island platforms, one for Caltrain and the other two for HSR. The split is partly a result of Caltrain's decision to stick with low platforms even at the Transbay Terminal, where no freight train will ever go.

The reason for the ongoing brouhaha over this one station is really quite simple. CHSRA has raised a very late red flag on the design of the DTX tunnel and train box, claiming it does not support the 12 HSR trains per hour (tph) each way that he thinks it should support, in addition to the 10tph Caltrain is hoping to run during weekday rush hour in 2025. I've argued that (a) any sane operator would anyhow choose to terminate some HSR trains further south long before reaching 12tph and, (b) that four platform tracks is anyhow enough for 12tph if you enforce some pedestrian flow control.

Tellingly, the red flag came - or rather, was shown in public - only after the Transbay Joint Powers Authority (TJPA) decided to apply directly for a slice of the HSR funds in the stimulus bill, rather than route that request through CHSRA. TJPA had previously been under the impression that 4tph would be sufficient for HSR operations. While that's true for the early years, perhaps even for several decades, CHSRA thinks its job is to deliver an infrastructure with enough capacity for the next 50, even 100 years. There is some method to that madness, as expanding a constrained downtown station decades after initial construction is usually extremely difficult/expensive or downright impossible.

While the timing suggested a political motivation, there does appear to be a real problem after all: the so-called throat, in which the six platform tracks have to converge to the smaller number in the tunnel, is very tight and by all accounts poorly designed. It constrains throughput for no good reason, Clem included a much improved version designed by Richard Mlynarik in his post.

Still, with a minimum curve radius of just 150m (~500ft), even Richard's improved version would effectively preclude the purchase of proven, off-the-shelf Japanese high speed trains - those need at least 280m, preferably more. SF real estate development should not drive HSR vendor decisions with statewide implications. To my mind, this is a red flag well worth raising - though CHSRA could and should have done so much sooner and publicly if TJPA was dismissive of this particular issue.

Station Requirements

Like any building, the aesthetics of the Transbay Terminal have their fans and their detractors. You can't argue about taste. What matters more to transportation engineers is functionality, which the current design might meet, sort of, for both CHSRA and Caltrain, but only after some modifications.

I've thought about this some more since my last post on it and have come to the following conclusion: the train portion of the design is suboptimal because planners interpreted the intent of SF voters (prop H, 1999) very narrowly as bringing the trains into the building itself. However, nobody except the developers really cares about that. IMHO, the voter intent was that the trains should stop within walking distance of the financial center, preferably also close to the bus terminal and such that an option of a second transbay tube to downtown Oakland is created.

If you subscribe to this more liberal interpretation, it is no longer essential to run tracks into the basement of the Transbay Terminal building. Rather, the focus can shift to a design that better meets the requirements of modern railway operations:

• large platform number (more than six)
  
• no platforms dedicated to any one operator
  
• all platforms full length (400m, i.e. 1/4 mile)
  
• all platforms straight
  
• all platforms level boarding (see Caveats below)
  
• high pedestrian flow capacity between trains and city streets
  
• minimum curve radius 280m (vendor flexibility, screeching noise)
  
• minimal cross-blocking of trains entering and exiting the terminus station
  
• all platform tracks run-through if second transbay tube is ever constructed
  

Train Station Under Mission Street

Fortunately, it's actually possible to meet these requirements in San Francisco, though it requires divorcing the design of the Transbay Terminal building from that of the railway station. The two would be linked via city streets, possibly a short underground pedestrian passage. If that's good enough for linking to BART and SF Muni subway, why the absolute requirement to put standard gauge trains into the basement? The upshot is that the Transbay Terminal should go ahead as planned, but without a train box or concourse level.

The following map and topology diagram show the concept I've come up with: a Central Station for San Francisco underneath Mission Street. Detailed design and construction would be far from trivial: many SF city buses use Mission to reach downtown, so tearing open that street would be quite disruptive during construction, even if it is done one block at a time. In addition, the street is quite narrow, around 85 feet including both sidewalks. That's only enough room for three tracks, two side platforms and narrow escalators/flights of stairs - which implies a lot of those would be needed to secure sufficient pedestrian flow capacity. Finally, there is almost certainly plenty of plumbing, ancient sewer mains, power mains etc. lurking underneath street level.


View Larger Map



Tunnel Route

The first thing you'll notice is that the DTX tunnel runs down 7th and Mission Streets, a very different route from the one currently proposed. I'm advocating just two tunnel tracks side-by-side, shared by non-compliant HSR and equally non-compliant Caltrain EMU trains, protected by appropriate signaling. Any legacy FRA-compliant trains need to terminate at 4th & King anyhow, since they're diesel-powered. Nevertheless, track sharing is only possible if FRA approves both Caltrain's request to switch to non-compliant EMUs and CHSRA's intent to buy proven, off-the-shelf but non-compliant bullet trains capable of cruising at 220mph.

One fringe benefit of the changed tunnel route is that no platform tracks are lost at 4th & King. Only a single 90 degree turn is required, in an area where real estate is probably less expensive than in Rincon Hill or downtown. In combination with the less complex excavation methods required for two single-track curved tunnels, this ought to permit a sufficiently generous curve radius. The map shows the maximum feasible radius of ~325m, there are various length constraints along Mission Street. A more detailed design would seek to optimize the radius as tunneling under existing buildings is expensive. Note that I have assumed the curve would be level; a helical curve would permit gradients of less than 3.5% in the vertical elevation change sections at either end.

My point is that the radius can be made large enough even for off-the-shelf Japanese high speed trains. This also eliminates any screeching noises from the long-wheelbase trucks required for stability at high speed. Crucially, it also increases station throat throughput because speed limits are proportional to the square root of curve radius. With appropriate tracks superelevation, it should be possible for outbound trains (non-tilt types) to take this corner at speeds as high as 60 mph, assuming the curve radii and speed limits for the various points along the way also have appropriate values.

The design objective should be to permit a train to pull away from any platform at maximum acceleration (~1.1 m/s^2 for Caltrain locals) and maintain that until it either hits the speed limit or has cleared the station's outer throat, i.e. the point at which tracks from the two levels converge. The minimum available distance for acceleration is about 1/2 mile, though trains on the lower platform face a 3.5% uphill climb for half that distance. Either way, any given Caltrain leaving an east platform should be able to clear the inner throat near 3rd Street within 75 seconds and the outer throat within 120. Maximum acceleration for HSR trains is more like 0.6-0.8 m/s^2 so they may take a little bit longer. Note that an incoming train may proceed past the outer throat as far as the inner one while a train is emerging from the same level; this provides a 15 second buffer.

Conclusion: as long as the curve in the access tunnel can be taken at fairly high speed, the elongated nature of the station layout does not appear to present a throughput bottleneck since the maximum time required to clear the outer throat is still less than the absolute minimum time separation imposed by the two-track access tunnel, i.e. 150 seconds at 24tph for HSR and Caltrain combined. Platform dwell times of at least 16 minutes are possible even at this insanely high level of traffic, which SF will almost certainly not attract in the next 50 years - if ever.

The downside is that the Mission Creek outfall needs to be crossed at grade, so a short section of 7th Street would lose two traffic lanes. More significantly, Townsend Street would be permanently severed at 7th unless an overpass were constructed.

Throat And Platform Layout

The second thing you'll notice is that the approach to the station is both long and straight, ideal conditions for designing a throat for minimal interference. In this case, the inbound and outbound tracks need to split into two levels that I call -2 and -3 for reasons that will be come obvious shortly. This split begins immediately east of the curved section. By the time the tracks reach Jessie St West, they need to be stacked 2x2 on top of each other. This ensures that any inbound trains waiting to reach a platform can wait west of 3rd Street on the correct level, without blocking inbound trains on the other level.

Near 3rd Street, the two tracks on each level first combine into a single track and then immediately split via a three-way point into a through track and sidings left and right of it. These sidings are the west platform tracks (2-1, 2-2 & 3-1, 3-2), each with its side platform. A second three-way point near Shaw Alley reconnects these sidings to the through track. East of this point, the through track may descend for a block to compensate for changes in the surface level (at-grade does not mean constant elevation above MSL). Regardless of length, trains always stop on the west platforms such that one end is at Shaw Alley.

A third three-way point at 1st Street provides access to two additional platform tracks east of that location (2-3, 2-4 & 3-3, 3-4). Regardless of length, trains always stop on the east platforms such that one end is at 1st Street. Space should be reserved for a future fourth three-way point reconnecting the east sidings to the through track, for reasons that will become obvious shortly.

Since there is no room for an access platform, the through track between these east sidings can only be used for train storage. Perhaps it could also be used as a tail track for the western platforms if cleaning/provisioning staff board and alight there. However, the only emergency escape route would be at Spear Street, which implies walking the length of the train first.

The layout described above means trains don't block each others' movements any more than necessary. The longest wait states would occur for an inbound train waiting for another to clear one of the east platforms, since that needs to travel up to half a mile first. At an average speed of 20mph along the center track, that would take 90 seconds. The worst-case wait state for a western platform would about a minute. In practice, well-planned operations would minimize wait states or eliminate them altogether by slowing inbound trains down rather than forcing them to come to a full stop. Worst case, there is room for one full-length train between Jessie Street West and 3rd Street.

Operationally, any given train would always stop such that one end ends up at 1st Street, within half a block of the Transbay Terminal building. In addition to supporting regional buses, the building would also contain the customer service counters for train operators, baggage depot, police station, shops, cafes, lounges/waiting areas, bicycle parking etc. Taxi and city bus stops are located on the plaza between Minna and Mission, Fremont and 1st. In other words, the concept of a multimodal hub is preserved even though the tracks are not underneath the building.

The train station would be really a bare bones affair: just the trains and access infrastructure plus some ticket vending machines and restrooms at intersections with cross streets. Mission Street isn't wide enough to accommodate any other facilities on the platform levels.

Concourse Level

Strictly speaking, there is no need for a formal concourse level at -1. Since the design uses side platforms throughput, surface streets could be used to access all of them. However, given the anticipated number of passengers, it is safer to provide pedestrian underpasses across Mission Street, even though that means digging a deeper (i.e. more expensive) trench than would otherwise be necessary. Moreover, the desire to provide four full length platforms per level means long walks are inevitable for some passengers on full-length trains. The concourse level would therefore feature moving walkways in both directions along its entire length, interrupted at the eight locations at which there are exits to the surface on both sides of Mission Street.

To either side of these central moving walkways would be regular ones, about 10 feet wide each. To either side of those would be the baggage screening areas, if Homeland Security requires any. Airport-style check-in is possible but usually (a) conductor(s) on board the train will inspect passengers' tickets. Note that security procedures are pointless unless they are implemented at all HSR stations. In any case, terrorists haven't attacked a long-distance train in Europe since Carlos the Jackal did in 1983. Instead, they've targeted subways and commuter trains as well as high speed tracks. Train stations are also at risk.

Optionally, staff could prevent passengers waiting to board from descending until they get a signal from colleagues below that all arriving passengers have cleared the platform. Unless the fire marshal requires this at all times, it would normally only be done during peak periods to avoid excessive congestion on the platforms. Note that the platforms on the two train levels would feature multiple stairs/escalators to the concourse level. Escalators intended for the disabled, women with baby strollers etc. would connect all three levels. Connections directly to the surface are ok only if Homeland Security decides it doesn't need to enforce access control to the platforms.

Pedestrian Cross Passages

A pedestrian passage underneath 1St Street between the train station and the Transbay Terminal building would not be absolutely essential but nevertheless very useful, given the vehicle traffic on the surface. Such a passage is currently planned as an optional extra between the building and Market Street, but under Fremont Street. Note that in the station design discussed in this post, the building would not need a concourse level for transportation purposes, just stairs/escalators/elevators to the pedestrian passage, if any. Moving walkways along this 200 foot stretch would be convenient for passengers and increase throughput capacity.

Additional pedestrian passages under Main and 2nd Street could connect the train station and indirectly, the Transbay Terminal building to both Embarcadero and Montgomery Street BART/SF Muni. Again, not strictly necessary but useful.

Note that all these underground pedestrian passages would provide shelter against the elements. Unfortunately, they may also attract pickpockets, buskers, alcoholics, drug addicts, graffiti artists, homeless people and others just hanging out for no apparent reason. Bright lighting, ventilation, cleaning and security patrols are needed to ensure passengers will feel safe and comfortable enough to use these facilities. It may make sense to ensure the passages are private rather than public property so security has a legal basis (trespassing) for evicting disruptive individuals.

Phasing And Extension to East Bay

What I've described above is actually the fully built out terminus station. If desired, construction could be divided into two phases to accommodate budget constraints. Phase One would be the access tunnel via 7th an Mission plus the four west platforms, possibly the pedestrian cross passages to the the Transbay Terminal building and Montgomery Street BART as well. Phase Two would be the east platforms beyond 1St Street plus the pedestrian passage to Embarcadero BART. The west platforms could already be in operation at that point.

If and when a decision is made to build a second transbay tube, the Mission Street station design affords a fairly straightforward if expensive connection via Point Alameda and into downtown Oakland up Franklin. On the SF side, the tracks should already be deep enough to avoid conflicts with the descending SF Muni subway tracks under the Embarcadero. There is enough room for the through track at level -2 to descend to level -3 between Spear Street and the water's edge. However, unlike the west throat, there is no need to double-track this new one on the east end: instead, the four platforms on the upper level would be used for inbound and the ones on the lower level for outbound trains (or vice versa). This operations change turns all eight platform tracks into run-through types, thanks to the four three-way points installed on each level.

In addition, the presence of a through track in each direction would permit trains to bypass all of the platform tracks. That could be useful for e.g. high speed cargo trains if a transshipment terminal were built in the East Bay or, for trains supporting a major sports or other event on Point Alameda or in Oakland. Normally, however, trains would dwell for a considerable amount of time in SF. Even at 24tph for HSR and Caltrain locals combined, having four platforms each way available means dwell times of close to 20 minutes would be feasible.

Caveats

I've already touched on a number of caveats, such as the consequences for 7th and Townsend Streets and, the need to pass under SF Muni tracks at the Embarcadero. In addition to those, there is a potential conflict with the planned SF Muni Central Subway. That is supposed to dive under the BART tracks at level -3 and, it looks like the chosen alignment (alternative 3B, Fig 2.12 would be deep enough at Mission Street to avoid a conflict with the alternate heavy rail access tunnel described above. However, if heavy rail station under Mission Street is considered, the clearance issue at 4th Street ought to be double-checked before ground is broken on the Central Subway. I don't have a good sense of how the surface grade changes between 4th and Embarcadero along Mission Street. The heavy rail tunnels should be level from 3rd to Shaw Alley and from 1st to Spear Street yet still deep enough to permit a concourse level plus a future extension to Oakland.

Another caveat is that passengers need to know not just the platform but also the car number of their train to descend at the appropriate point. The preferred approach is mandatory seat reservations (cp. TGV in France), the receipt can then include this information. Given the width constraints, pedestrian traffic along the platforms should be minimized. Reservations also ensure there are no standees on the train and that no-one needs to walk far inside the train to reach their seat.

Also on the receipt could be helpful hints, e.g. the nearest BART/SF Muni subway/SF Muni streetcar. Indeed, a good reservation system would ask about your connecting transportation to offer you a seat that minimizes your transfer distance. That could be printed on the receipt, along with an indication of how many minutes to budget for an comfortable transfer incl. security screening, if any. The flip side of seat reservations is that a late change to the platform, especially from one west of 1st Street to one east of it (or vice versa), would cause significant inconvenience for passengers.

Finally, I've assumed throughout that all eight platforms in the design would be created equal, i.e. that all would feature level boarding at the international standard of 3'6" (1067mm). Caltrain is hamstrung by a ridiculous 1948 rule intended to protect freight railroad workers hanging off the sides of cars. Is it really appropriate to perpetuate ye olde tyme practices to the detriment of passenger convenience and throughput capacity, in a station that no freight train will ever enter? IMHO, if Caltrain wants access to any downtown station in SF, it needs to buy EMU equipment that can cope with both level boarding and the lower level (2'1" = 639mm) that the platforms at its other stations are built to. If UPRR and CPUC have no objection, those could be upgraded to level boarding as well over time.

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Heads Up: Neighborhood meeting on HSR for residents of the Willow Glen neighborhood in San Jose, on Wednesday, April 8 at 1292 Minnesota Ave from 7-9pm.

The purpose of the project-level EIR/EIS phase is to nail down how the HSR alignment should be constructed in each location, after close consultation with the affected communities. The starting point will be what CHSRA consultants suggested for the purposes of cost estimation prior to the election. This information has been available online since 2007, though you do have to look for it. The Authority is a planning body, i.e. a bureaucratic organization - most of its documents were designed for hardcopy rather than the web.

The objective of the HSR project is to deliver a net gain for the state California, especially for the cities served by stations. The following resources may help you understand what CHSRA has done to date regarding San Jose and the Willow Glen area in particular.

Resources:

• CHSRA Google Map of implementation details used for cost estimation purposes.
  
• CHSRA Pacheco Pass implementation details such as height of structures, embankments as used for cost estimation purposes. Willow Glen is on page 4.
  
• CHSRA Station Fact Sheets, San Jose Diridon is on pp41
  
• CHSRA Various Cross Section Drawings, San Jose Diridon is on p20
  
• CHSRA Speed Limit Ranges for the route (NOTE: part of draft EIR/EIS documentation, no longer present in the final version. Possibly out of date, as Altamont Pass and East Bay sections have since been scoped out of phase I and phase II of the HSR project.)
  
• CHSRA Capital Cost Estimates for the Bay Area to Central Valley section (line item details)
  
• CHSRA Bay Area to Central Valley Final Program EIR/EIS
  
• UPRR owns the existing rail right of way between San Jose Diridon and Gilroy, Caltrain and Amtrak have trackage rights on UPRR's tracks. HSR needs land for two additional dedicated tracks, preferably adjacent to the existing ones. See our posts on How Important Is UPRR To California HSR? and Union Pacific Speaks for more information.
  
  
• How others do it: first pass analysis of alignment options and local impacts by San Mateo city planning staff, prepared for the city council
  

If you plan to attend this meeting, you may want to download selected resource documents at home and bring them along on a laptop.