The Palmdale (Airport) HSR Station

by Rafael

The route CHSRA has chosen for the Bakersfield-Sylmar section runs through the Tehachapis, the Antelope Valley and Soledad Canyon. This is substantially longer than the direct route via Tejon Pass. The primary factors in favor of the longer route were total length of the tunnel system (21 vs. 34 miles), the ease of crossing major faults at grade and geology risk. A secondary goal was HSR service for the half-million people who live in the Antelope Valley.

However, this post will focus on the potential for leveraging HSR to finally turn Los Angeles World Airports' (LAWA) vast Palmdale airport (PMD) property into a viable commercial proposition. It is the only location in all of southern California at which additional runways could fairly easily be added in the future, east of the existing ones.

While it is absolutely not CHSRA's job to also take on regional planning on how best to relieve LAX, there is a need for interface planning if LAWA, an LA county agency, and the city of Palmdale want to at least preserve the option of using PMD for that purpose. As discussed below, simply siting an HSR station in the general vicinity of the airport, several miles removed from it, will not be good enough.

The following map shows current plans for the starter line and station plus alternatives discussed below.


View Palmdale Airport HSR station in a larger map

Right of Way for HSR

First, though, there is the non-trivial issue of securing ROW for laying HSR tracks between the Tehachapis and Soledad Canyon at all. CHSRA's current plans assume a dedicated ROW for HSR in the UPRR/Sierra Hwy corridor (red line).

Palmdale-Mojave is part of UPRR's core ROW from the LA/LB harbors up the west coast. This rail freight corridor is much busier than the one up the central coast. At first glance, it looks plenty wide but UPRR's has in fact already quad-tracked some sections. The Sierra Hwy frontage road runs about 50 feet west of the tracks north of Palmdale Metrolink, where it cuts over to the east. There's a linear park and also businesses to either side of UPRR ROW in Palmdale itself. There are also several freight spurs and the turnoff to Hesperia to contend with.

If UPRR hasn't already informed CHSRA that its own ROW is not available for HSR, expect that it will. This is going to be a recurring theme. The area isn't as densely built up as south San Jose or Gilroy, but actually securing a greenfield ROW in the UPRR/Sierra Hwy corridor could still prove surprisingly difficult. CHSRA's Google Map of the route (pls zoom in) shows the alignment in the Lancaster-Palmdale section as dead straight and entirely at-grade, with no flyovers for the Sierra Hwy nor the UPRR tracks that cross the planned alignment. These are relatively small details, but their omission is noteworthy.

However, given that the Tehachapis route has been identified as the one with the shorter tunnel system and lower tunneling risk, I expect that CHSRA will in the end be able to obtain a ROW, even though speeds will need to be high to compensate for the extra 40 miles the High Desert route entails. Worst case, there's always plan B: the extra-wide hwy 14 median (pink line). That would be longer, limit feasible speed, preclude the desired intermodal with Metrolink and require future detour tracks to connect to the airport at all. However, as we shall see, a wye off the main line might not be a bad idea in any event.

Relief for LAX: Palmdale, Ontario or both?

Palmdale airport began life in 1940 and has always been used by the US Air Force and defense contractors. Between 1966 and 1995, LA county acquired a total 17,750 acres of land east and south of the Air Force property via eminent domain, for the specific purpose of developing a civilian "Palmdale Intercontinental Airport". However, that never came to fruition, precisely because there was no high speed ground transportation link into the Los Angeles basin. In December 2008, United Airlines canceled the only remaining route to SFO in December after subsidies ran out.

LAWA has even surrendered its commercial aviation license for PMD to the FAA, at least for the time being. It is considering using part of the facility for a solar power farm. That's great for the environment, but perhaps not the best location for that technology. As reported in Future So Bright, that could potentially blind pilots. As long as the city of Palmdale remains the only cheerleader for PMD, it is likely to remain a ghost airport, much like SBD.

For now at least, LAWA appears to have given up on ever making PMD a successful proposition and is concentrating on the active Ontario airport to relieve LAX. It is slated for inclusion in the phase 2 spur, but it's not yet clear which ROW will be used to run the tracks. UPRR is not interested in sharing its primary ROW out to Arizona and points east. The alternative, getting to from LA Union Station to I-10/Archibald, is also non-trivial. Among other considerations, the I-10 median is where the Anaheim - Las Vegas maglev line was supposed to run. Using it for steel wheels tracks would officially kill that project, though IMHO that might not be a bad idea. There is absolutely no need nor ROW for two mutually incompatible HSR lines through the San Gabriel valley.

On the face of it, LAWA's preference for Ontario appears sensible enough: there may be not be a need for two relief airports for LAX. That said, perhaps the agency is taking a bit of a gamble in abandoning PMD quite so soon now that the phase 1 HSR starter line is going to run so close to it. More to the point, LA county isn't thinking beyond its borders, given that HSR could mean a fast single-seat connection to Anaheim, Bakersfield and even Fresno. The southern Central Valley is poorly served by airlines and, there are currently no plans for a shuttle train between the Fresno HSR station and FYI airport.

Moreover, if both California HSR and DesertXPress tracks are built and then connected via the existing SR-58 transportation corridor, PMD could even relieve McCarran airport in Las Vegas and eliminate the need for a brand-new airport between Jean and Primm. The potential catchment area for PMD isn't so much a circle based on driving distance as a (set of) very long high speed rail line(s) connecting it to multiple large population centers. That the Antelope Valley has a sizable underserved population in its own right is almost gravy on top, at least if Palmdale is smart enough to prevent encroachment on the airport in the future. The whole point of PMD would be to get away from noise ordinances etc. and run the airport 24/7 for passenger and cargo flights.

LAWA's position illustrates what happens when you allow a single county - albeit a huge one - to make decisions that anywhere but California would be the business of many counties, the state or even multiple states.

HSR is a potential game changer for PMD

With HSR, non-stop line haul time to Palmdale is estimated at 27 minutes from LA and 46 from Anaheim. Those sorts of times are needed to give PMD a fighting chance of ever relieving LAX, but keep in mind they are for non-stop trains and station-to-station. In terms of connecting transit, LA Union Station is already a busy and growing regional transit hub. Anaheim ARTIC is supposed to serve a similar function, but Orange county has no subway, light rail or BRT service. The Disneyland monorail will be extended and OCTA bus service improved.

In Palmdale, the current plan of record is to build the HSR station at the "Palmdale Transportation Center", i.e. the local Metrolink station/bus stop (see map at the top of this post). The city's modest plans for transit-oriented development considered only Metrolink, not high speed rail as that was still a very uncertain prospect at the time. They also did not consider that HSR would need a dedicated ROW to run in. Unfortunately, the Metrolink station and PMD's existing small passenger terminal at 41000 20th St E are separated by a 3.1 mile drive. With zero flights out of PMD, there is of course no shuttle bus to the passenger terminal.

For now at least, the Antelope Valley evidently doesn't have a sufficiently large and/or affluent regional population to sustain any commercial air service at all on its own. The US government forces airlines to offer its employees deeply discounted fares. Therefore, if it wants to revive its airport, the city of Palmdale needs to leverage the HSR project to bring in additional airline passengers for the LA basin and the southern Central Valley. Given that HSR will serve the major population centers within the state and possibly even connect to Las Vegas on day via co-operation with DesertXPress, the whole notion of a strictly regional airport just for LA county needs to go out of the window. Either there is a strategic decision to develop Palmdale into an HSR-centric "LAX East" or, CHSRA has to stop talking about Palmdale as an airport. It takes a lot more than idle runways three miles down the road.

Trips by plane + HSR are still a foreign concept in Southern California. If it is to catch on, the end-to-end experience in Palmdale and/or Ontario must receive high marks from passengers.

Focus on big birds

A well-run and frequent shuttle bus service to and from the existing terminal might seem like a useful loss leader to get the ball rolling, but very quickly further growth would depend on much closer integration with the primary feeder service, i.e. high speed rail. More to the point, it will require a strategic decision to aggressively relieve LAX of certain types of traffic, e.g. the A380 that it simply wasn't built to handle. LAX gets by, but only with special measures that reduce its throughput.

That class of aircraft is intended for transcontinental and transoceanic hub-to-hub traffic, so a large fraction of passengers will transfer to connecting service at one or both ends. Typically, that means connecting short-hop flights, exactly the kind HSR is supposed to replace in California, perhaps - one day - out to Las Vegas. However, connecting flights to other states are also needed, so PMD has a very deep hole to climb out of. In practice, that would mean certain airlines or airline consortia would have to switch from LAX to PMD, at least for part of their long-distance operations in Southern California. Relative to the status quo, that implies low airport taxes, unrestricted night flights, a cargo forwarding facility plus a major leap of faith in the California HSR project. The risk will be much lower once the first trains are up and running.

No airline will fly big birds into PMD solely to serve passengers who want to catch connecting flights. The airport has to be perceived as a destination in its own right as well, there has to be a large "local" catchment area. What HSR could do is redefine "local" to well beyond the Antelope Valley and even beyond LA county.

Note that the upcoming Boeing Dreamliner and Airbus A350 aircraft are intended to provide affordable, direct long-distance flights between secondary destinations, precisely to avoid having to connect to another flight. However, since connecting ground transportation is always necessary for any airport, it's possible airlines would prefer to use PMD - or ONT, for that matter - for flights based on these planes, in conjunction with onward travel by HSR.

New passenger terminal with HSR tracks

Around the world, several airports have heavy rail train stations integrated into their terminal buildings, e.g. Atlanta Hartsfield, London Heathrow, Paris CDG, Frankfurt and Amsterdam, no doubt others as well. Some have standard-speed, some also high-speed train connections.

There is a chance LAX might get a standard-speed heavy rail shuttle along the Harbor Subdivision Transit Corridor, but that will do nothing to relieve air traffic congestion there. Note that in Vienna (Austria), there is a special point-to-point shuttle train service that let airline passengers check in and even drop off baggage at a downtown location. Security screening and baggage pick-up is still at the airport, at least for now. I'm not aware of other examples of integrated baggage handling, though IIRC the Dutch railways used to offer it at selected train stations at one point in time.

Some airports, e.g. Birmingham (UK), have people movers that shuttle passengers between the terminals and a separate but nearby train station on a main railway line. Similar solutions are planned for OAK and SJC, one already exists for SFO though not out to the multimodal station at Millbrae. ONT may also get a people mover but the very remoteness of PMD means nothing less than an HSR station physically inside a new passenger terminal may work there.

In terms of timing, the HSR starter line may well be completed before there's any commitment to invest in any new integrated terminal at PMD. If the HSR connection at ONT pans out, there may never be. To at least keep the option open at this stage of HSR planning, the city of Palmdale could decide to go for broke and move its HSR station to a site further north, where a new terminal could be built right next to it at some indeterminate point in the future.

If CHSRA manages to secure a ROW in the UPRR/Sierra Hwy corridor, the preferred location for such a new terminal is already occupied by the huge USAF plant 42, shown in red on the map. Since that's a major cluster of employers in the area, it's very unlikely it could be moved. Any plan for the airport will have to work around that constraint. There is room for a modest terminal with ~15 JB gates just north of the plant, shown in green on the map. However, its future growth would be constrained on all four sides, since the end of the runway must remain clear for safety reasons. Also, this terminal would be far removed from the airport's other, longer runway, so we'd be back to shuttle buses or people movers for future expansion.

Besides, the north runway is actually part of the USAF property and may not even be available for restarting/expanding civilian aviation. Even the south runway is technically only leased in an effort to kick-start commercial aviation. Future expansion would definitely have to occur east of the existing runways.

Wye for detour tracks

An alternate approach would be for the LAWA/the city of Palmdale to at least reserve land for a future wye off the starter line to an integrated terminal at a site that best serves the needs of airlines, i.e. one with more room for JB gates and shorter taxiways to the longer of the two runway. That would mean either expanding or replacing the existing terminal south of it or else, a new one east of it. The detour would be used only by trains that actually stop at the putative integrated terminal instead of the downtown Palmdale station. This could include High Speed Cargo trains, if CHSRA decides to allow those on its network and plans for appropriate transshipment terminals. All through trains would stay on the main line, bypassing the airport.

Note that this wye would have to be fully grade separated and feature fairly large curve radii on account of the high speeds on the main line. Suggested alignments are shown in yellow for the case of a ROW in the UPRR/Sierra Hwy corridor for the HSR starter line and in orange in a hwy 14 scenario. Where the tracks would run east of the wye depends on where the terminal building would go.

If this concept is selected, grade separation structures need to be designed and built to support such a future wye. The actual rails and switches for it could be but would not have to be laid just yet, they can be spliced in at a later date.

The HSR station on the starter line should be modest and sited at the location best suited to serve the people who live in Palmdale/Lancaster. Where exactly that will be depends on the ROW CHSRA ends up with. If and when a new airport terminal is actually planned, it will be an entirely separate project and need to include the construction of the wye and detour tracks to a second HSR station in the area, located directly at that terminal. Funding for that track work would be outside the scope of the California HSR project as such.

Conclusion

Billing the Palmdale HSR station as "Palmdale Airport" is highly aspirational at this point. Without a strategic decision to invest in a new terminal building with an integrated HSR station, a sufficient number of JB gates and room to grow, the fact that the HSR starter line will run past the airport's runways means exactly squat diddley. Since Ontario is in many ways a more promising candidate for the job of "LAX East" on the back of HSR, LAWA's decision to focus on that is understandable. However, it is also risky, since it's not yet 100% certain that an HSR station close to the ONT terminals will actually be feasible.

The city of Palmdale has a chance to revive PMD, but only if it dares to think big and formulate a bold, credible plan for integrating its airport more tightly with HSR than any other in California (with the possible exception of Lindbergh Field). It needs to sell this not just LAWA but also to the state of California and the cities of Bakersfield, Fresno and Anaheim. CHSRA could be a partner in this effort by giving the city of Palmdale some leeway on where its station on the starter line should go.

If current plans are changed to anticipate a future wye and detour tracks, the siting of any new integrated passenger terminal for PMD would not depend on CHSRA securing a ROW in the UPRR/Sierra Hwy corridor. This option would be minimally more expensive up front and limit CHSRA's involvement with regional/statewide airport planning to creating just an interface point.

If, after a careful integrated planning effort, the decision to abandon PMD is upheld in spite of the HSR project, so be it - go ahead and repurpose the land for a solar power plant. But perhaps, that should not be up to LAWA alone. While the good people of Palmdale would no doubt disagree, the hassle with UPRR plus losing the airport would make many voters around the state wonder if the additional tunneling cost and risk through Tejon Pass isn't worth it, after all. Shaving twelve minutes off the SF-LA line haul time or, creating breathing room for CHSRA to avoid UPRR statewide, would be no small prize.

Upcoming CHSRA scoping meetings for Bakersfield-Palmdale

• Bakersfield
  • Where: Red Lion Hotel, 2400 Camino Del Rio Court, Bakersfield, CA 93308
  • When: Tuesday, September 15, 2009 3:00-7:00pm
• Tehachapi
  • Where: Stallion Springs Community Center, 27850 Stallion Springs Drive, Tehachapi, CA 93561
  • When: Wednesday, September 16, 2009, 3:00-7:00pm
• Palmdale
  • Where: Chimbole Cultural Center, 38350 Sierra Highway, Palmdale, CA 93550
  • When: Thursday, September 17, 2009, 3:00-7:00pm

Scoping meetings for the Los Angeles - Palmdale section were held in April and quite rightly focused primarily on the sections up to Sylmar and through Soledad Canyon. The discussion of if and how HSR could help southern California leverage Palmdale airport is better suited to the upcoming Palmdale - Bakersfield project-level EIS/EIR process.

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BTW: I'll be traveling during the week of Sep 7 and may not be able to contribute to the discussions on this blog much.

Innovation Place

Clem has a excellent overview of the tunnel and urban development concepts offered by a group calling itself Innovation Place. You can see some of their award-winning presentation or read more about the plan at Palo Alto Online. Clem's explanation of their ideas:

The crown jewel of Innovation Place is a complete transformation of the University Avenue station area, as envisioned in the team's graphic above. High speed rail or not, this area of Palo Alto is in dire need of a redesign; today, access between three important zones of activity (the University Avenue shopping district, Stanford University, and the Stanford Shopping Center) is a circuitous and dysfunctional jumble that is both unpleasant and time consuming to navigate, whether by foot, bike, car or bus. Neighboring areas just a few hundred feet apart feel miles away from each other.

The remainder of the Innovation Place proposal consists of a 31-acre linear park adjoining Alma Street, featuring a bike and pedestrian path and reuniting the two halves of Palo Alto formerly separated by the train tracks. The additional cost of putting the tracks underground would be financed by selling $700 million worth of air rights for development.

Go over to Clem's blog to read the full details and see some very intriguing designs, along with Clem's thoughts on the concept's strengths and weaknesses.

Personally I think this is exactly the kind of work that Palo Alto residents ought to be producing. Rather than trying to say "no" to the HSR/Caltrain project, the thinkers behind Innovation Place have said "yes" to integrating it into their community. It would be wonderful if Menlo Park and Atherton chose to follow this model instead of wasting taxpayer money on a lawsuit that is doomed to fail.

As to the concept (which should not be described as a "proposal" at this point since it isn't at that level of specificity), I like it. There's the question of the possible roller-coaster effect of a high speed train entering a tunnel for Palo Alto only, and whether $700 million is enough to underground the route. It's also unclear whether Union Pacific will go along with this, as it would pretty much eliminate their ability to continue freight operations over that section of track (although they could theoretically revive the Dumbarton corridor and use the shared tracks along the rest of the HSR/Caltrain corridor north to SF). But this is absolutely something worth exploring.

HSR and TOD

The middle of a severe recession led by collapsing real estate values may not seem like the best time to start talking about developing property around planned HSR stations. But the economy will eventually recover (even on the slow timescale forecast by many economists there will probably be real recovery between now and 2018) and that in turn will mean developers will bring the capital and the will to use HSR stations as anchors of new projects.

The CHSRA has always emphasized their stations as bringers of urban density; you can see it in the NC3D animations produced last year for the Authority. Transit Oriented Development (TOD) is one of the strongest selling points for high speed rail, as it will help provide needed new housing in city centers, spur the development of other housing, commercial, and retail properties, and help act as magnets for bringing growth back into the cities and away from the exurban sprawl that characterized California's last period of economic growth (a sprawl which was directly responsible for the current economic collapse).

The question, as the San Diego Business Journal points out, is timing:

“I think not only is it something that is a good thing, it’s certainly going to be a phenomenal planning tool for the next generation of growth,” said Perry Dealy, president of Dealy Development. “The opportunity to take the high-speed stop hubs and convert them to maximize their mixed-use, high-density potential is great. You’d have what I’d call a TOD, transit-oriented design, starting with residential, work-live, retail, entertainment and other kinds of venues that are part of the mixed-use characteristics.”...

Dealy said that the type of project he has in mind would ultimately cost $1 billion to $2 billion. It would entail acquiring land to build on, adding or refurbishing infrastructure, and preparing a master plan.

“There is demand for the region to grow, we’re definitely going to add a million people, maybe not in 10, but in 12, 14 years it’s going to happen,” said Dealy. “Now’s the time to actually get these concepts defined.”

Of course, Dealy will have even more time than that to plan for San Diego, where revenue service may not begin until as late as 2030. But for some of the other stops, such as Anaheim, Fresno, Gilroy and San Jose, now may well be the right time to get TOD concepts under way, especially as cities start evaluating land use rules surrounding the proposed HSR stations.

Some developers aren't convinced there's any rush to get plans started:

Shawn Tobias, project manager at Houston-based Hines, a real estate firm and commercial developer, stated that he doesn’t see that much of a push from the development side to start planning for a project like this immediately.

“I think (development) firms in general right now tend to be shortsighted in terms of their business, just to make sure that they’re weathering the current conditions well enough, but planners are certainly into the future,” said Tobias. “Whether that becomes a reality is a different situation because the real challenge is integrating the plan within the existing municipalities, but it certainly is on Hines’ long-term radar.”

Tobias cited economic factors for the reasons that some developers have chosen to focus on more short-term projects.

“I don’t see a planning rush right now because most people are in survival modes,” Tobias said. “Once the economy starts to heat up and there’s more demand for development, I think you’ll see more firms clamoring for this.”

Of course, Hines isn't really saying anything that different from Dealy - both agree that HSR TOD will make a compelling financial opportunity for developers, investors, and buyers, but they aren't sure whether there is the resources out there right now to get this started given the economic climate.

As HSR TOD plans begin to take shape we'll start covering them in more detail here on the blog. One issue that the HSR stations raise related to development is whether there will be overnight and long-term parking allowed at these stations, a question Rafael brought up in the comments to yesterday's post. If such parking is allowed, Rafael rightly argues, it could mitigate against TOD, especially in lower density locations like the Central Valley.

Parking is a big issue when it comes to development in existing urban centers. TOD and density advocates have increasingly pushed to limit or eliminate city planning codes requiring new developments to provide a fixed number of parking spaces, and more attention is being drawn to the drawbacks of urban parking lots.

On the other hand, overnight and long-term parking would represent a potentially significant revenue stream for the CHSRA. There are many years of studies ahead that will examine this question, which will have an impact not only on how Californians interact with the HSR trains, but how the HSR system interacts with its surrounding urban environment.

La Vitrine

Note: Clem Tillier, who owns the Caltrain-HSR Compatibility Blog, kindly contributed artwork to this post. Unfortunately, I'm artistically challenged but I hope the cross-section drawings help to get the idea across.

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In a follow-up to Thursday's welcome news that Palo Alto officials are waking up to the potential downsides of letting tunnel boring machines into suburbia, this post presents a possible alternative implementation for HSR in the mid-peninsula that may also be of interest elsewhere (e.g. Fullerton-Anaheim-Irvine). It seeks to minimize local environmental impacts, i.e. visual clutter, noise, vibration, re-configuration of cross-roads and changes to established road traffic patterns. This does involve some trench construction, but digging can't be avoided if above-grade solutions are deemed unacceptable: wherever grade separation is required, either the roads or the tracks will have to descend.

More detailed studies will be required to decide which is preferable, but my hunch is that the 150-year railroad ROW might actually be the easier of the two options, as existing plumbing, gas, telephone and utility lines will at least be documented more accurately and may anyhow run deeper to avoid vibration damage.

Before I delve into the gory details, allow me me clarify a few things up front:

1. The suggestion described below is my own, it does not come from CHSRA nor their consultants for this segment (HNTB). My objective is to discover what is and what is not acceptable to residents of the mid-peninsula towns of Redwood City, Atherton, Menlo Park, Palo Alto and Mountain View. No sleight is intended to residents of other peninsula towns, that's simply the geographic scope I selected to illustrate the concept.
   
   
2. I've assumed that CHSRA will win the pending court case regarding the EIR/EIS process and, that it will secure the ROW to Gilroy needed to implement its preferred route (as in: not mine).
   
   
3. Implementing this would be a good deal more expensive than the original proposal of a retained fill embankment. The funding gap would need to be quantified and appropriate financing negotiated. CHSRA is having enough difficulty scraping together the ~$33 billion it has already estimated for the starter line. That means any solution that goes well above-and-beyond would require that cities tax themselves and/or rustle up other funds not already available to CHSRA.
   
   It's also worth looking HSR implementation (pls zoom in) in the peninsula as a whole. For example, it's not immediately obvious why CHSRA is proposing a tunnel between San Tomas Expy and San Jose Diridon station, so local officials should ask for an explanation and request an alternative if appropriate. This may involve co-operation and cor-ordination with other peninsula communities and multiple railroads, but that should not preclude an attempt at overall optimization. Even if that succeeds, there still has to be some element that will keep every town and hamlet along the route from seeking upgrades or else, cost escalations will sink the entire HSR project very quickly indeed. That's not an acceptable strategy for mid-peninsula cities to pursue.
   
   
4. Unfortunately, HSR construction will be a noisy, messy affair pretty much regardless of which option is chosen. It may be possible to phase construction such that there are always two tracks available for Caltrain and heavy freight trains. However, the work might proceed faster and at lower cost if the old single-track Dumbarton rail bridge were restored first so UPRR's Mission Bay Hauler trains could be diverted, perhaps permanently. This would be at their option, since they have a limited easement on the Caltrain ROW - even a say in who else gets to use it! During critical periods in the construction schedule, Caltrain could maintain some limited SF-SJ service via temporary trackage rights on UPRR's Alviso line and also offer temporary bus services via Central Expressway/Alma/El Camino Real.
   
   Considering its western trestle and approach burnt to a crisp in a suspicious fire in 1998, restoring this 100-year-old bridge would be a marginal proposition at best (and one CHSRA has not budgeted for). After HSR construction, a restored bridge could support UPRR, a few Caltrains across to Union City, perhaps even a new ACE service up to SF - figure around half a dozen trains each way per day. Note that replacing the bridge with a new dual-track causeway with bascule sections would be preferable for seismic and fire safety alone, even if it is only ever used for a limited volume of freight and commuter rail/Amtrak. Basically, the decision hinges on how much construction near and rail traffic through the DENWR (founded in 1974) will be permitted at all.
   
   Sadly, the idea of running dozens of HSR trains through there at grade each and every day is almost certainly a non-starter. If the Altamont HST/commuter overlay ever gets built, CHSRA's plan is to run regional high speed trains down to SJ Diridon, not across Dumbarton and up to SF. This is why - for better or worse - I'm sticking with plan A here and trying to contribute to the process of finding an acceptable solution.
   

The Enclosure



In a nutshell, what I'm suggesting here for the mid-peninsula is to build an enclosure for all four tracks to minimize visual clutter from the overhead catenary system and especially, to keep bow wave and noise emissions isues to a minimum - even for trains moving at 125mph. At grade, the enclosure would be composed of two sides and a lid. The outside width of the enclosure would be 75 feet.

To conform to AAR specifications for tunnels, the sides would be 18' tall and then continue up along an arc. The definition of where the sides end and the lid begins is up to the architect. They would consist of a slender latticework of steel I-beams encased in concrete for protection against rust and fire, rather than conventional rebar.

The spaces in-between would be filled with large soundproof glass panes (possibly sandwich structures), probably triangular with rounded corners. These would be embedded in the latticework using a visco-elastic putty/dense foam interface to minimize stresses in the glass membrane in response to temperature, wind and earthquake loads. An example of how large glass panes can be supported securely yet flexibly is the mile-long terminal building at Kansai Airport near Kobe (Japan), which has withstood subsidence, typhoons and a major earthquake without damage to its glass skin.

However, the use of large glass panes would preclude the use of regular ballast, as small pebbles propelled by the aerodynamic forces of passing trains could damage them. The rails, too, can be damaged by ballast pitting. Instead, the concrete sleepers would be attached directly to a concrete foundation slab. A promising new Japanese approach based on ballast bags filled with a special non-toxic aggregate made from recycled materials could be applied to dampen rail-wheel noise beyond what the enclosure alone would achieve. Damping is most effective for medium and high frequencies, but those are the ones that the human ear is more sensitive to.

The idea is to create an airy, largely transparent structure with rounded edges along the top. This should massively reduce the claustrophic effect a tall solid embankment can have, something even an interesting surface texture cannot fully overcome. Thanks to the large glass panes, the result would be more like a giant version of what the French call a vitrine, showcasing products at a store or artifacts in a museum. Both metaphors seem apt, considering that passenger trains played such a vital part in the state's past and will do again soon. Peering through the glass, you would be able to see the trains passing but should hear no more than a quiet low rumble. That's because the lid eliminates virtually all direct transmission paths through the air, much like closing a door will greatly reduce noise coming from an adjacent room. The visco-elastic putty will permit the glass panes to move and even flex slightly in response to the bow waves of passing trains, lending the whole structure the grace of a subtle kinetic sculpture.

The lid would implement the circular arcs required by AAR for the walls of the outside tracks (used for HSR?) plus the relatively flat center section in-between. However, since the Caltrain/HSR tracks will need a couple of feet of additional vertical clearance anyhow, the wide span of the structure could perhaps be supported as a vaulted ceiling, completely eliminating the visual clutter of internal columns.

One stunning example of this concept is found at Santiago Calatrava's beautiful Satolas TGV station, located next to the regional airport in Lyon, France.



Ironically, the very success of the TGV service ended up depriving the airport of customers for domestic flights. Note that the Satolas station is much wider and taller than what I am suggesting for the mid-peninsula and, that its sides are open to the elements. Nevertheless, I hope the comparison gives you a sense of what a skilled civil engineer-cum-architect can accomplish. That said, pulling off a vaulted ceiling 75' wide would be a bit of a challenge in earthquake country.

The underside of the lid would be used to suspend the overhead catenary system or perhaps, space-saving overhead conductor rails from Switzerland that support speeds of up to 150mph, certainly good enough for Caltrain/UPRR use. There would be no need for the usual catenary poles.

In spite of the slender latticework, the rounded edges, the vaulted ceiling and the glass panes, the enclosure concept still implies a large above-ground structure, roughly 75 feet wide, ~28 feet tall in the center and literally thousands of feet long. Inevitably, it would dominate its surroundings, so it's not appropriate in all locations. As indicated above, it would also cost a pretty penny. Unfortunately, selling air rights above it to developers wouldn't be a viable option.

The Linear Park



That is why I'm suggesting that the upper side of the lid be leveraged for an elevated linear park serving the community, with the objective of boosting - rather than blighting - the values of nearby properties. Many options exist: if the edges of the enclosure are curved as suggested above, the park could be confined to the central portion of the ROW or feature cantilevered outriggers or both, to suit local requirements.

Many linear parks already exist, e.g. the new Highline in New York and the Promenade Plantée in Paris:



Both of these leverage abandoned elevated railroad rights of way, rather than the space above active tracks. However, Seattle's Freeway Park, Sam Smith Park and the Lid Park on Mercer Island (WA) are all built on top of major active transportation arteries. More recently, President Sarkozy of France has invited suggestions for yet another expensive grand makeover for that country's capital. Richard Rogers' entry would create park spaces above active railroad tracks and yards, though the scope of that is far more ambitious than what I'm proposing here.

In addition to safety railings, there might be value in installing bowers and pergolas to support climbing plants that provide shade and provide some formal structure at a human scale, cp. the Promenade Plantée video above.



Load restrictions at existing road underpasses may force architects to narrow the linear park to just a foot/bike bridge across a lightweight lid section that could be an architectural flourish or a more delicate feature spanning a (very) shallow pond or trompe-l'œil mural.







Trench Sections

In some parts of the alignment, the most appropriate solution may be to force the tracks to descend into a deep trench so they can pass under existing cross streets, to avoid vehicle access impacts to buildings along the first block to either side and/or intersections with frontage roads. Such constraints are more common where residential properties directly abut the Caltrain ROW. Note that trench walls require a certain thickness but that the lid structure would serve as a buttress. Engineers will have to work hard to fit it all into just 75 feet of width, but it ought to be possible.

The enclosure and the linear park above it would follow the elevation change of the tracks. Obviously, the latticework side walls would be replaced with solid concrete below grade level. In these trench sections, the park would actually run 2-3' above grade to support lush vegetation, e.g. using recycled water. The sides would be retained with heavy wooden beams or else sloped as a 2:1 embankment. Either way a suitable fence and/or hedge would be indicate the property line, that's a detail to be resolved at a later stage. Because edges of the lid would still curve down to the sides, there would be plenty of soil to support large shrubs and small to medium-sized trees. Bike and pedestrian paths would slope down toward cross streets unless traffic planners, civil engineers and landscapers decide that very low hump bridges would be preferable, e.g. to reduce excavation depth. Playgrounds, fitness parcours or (lightweight) outdoor sculptures might be appropriate in one location, perhaps a serene Japanese pagoda with water features and a rock garden in another. Again, plenty of scope for customization at the city or neighborhood level.

Optionally, tall graceful arches could be installed in some of these sections of the park to provide a visual frame of reference, support wire trellises and/or enhance outdoor lighting.





Ventilation

Along the entire length of the structure, there will be a need for ventilation funnels at regular intervals. These should be shaped to direct sound upward and feature a grate/net to prevent objects from falling in (or being lobbed in). If any train operator insists on running diesel locomotives through the structure, the funnels should feature quiet fans. Note that extremely strict EPA Tier 4 emissions regulations will be in force by 2015, these should be used in this enclosed structure.

Track Elevation Transitions

Here is where things get a little technical, feel free to fast forward to the next section if you're not so inclined.

The following map shows which sections of the Caltrain ROW I would recommend be left at grade (blue) and which might best be put in a deep trench (red). The green sections represent elevation changes. In cross-section, these S-ramps consist of vertical arc segments, typically connected by a straight slope segment. Note that these transitions are not identical for the Caltrain/UPRR and the HSR tracks. Freight trains are limited to slopes of 2.2%, whereas HSR trains can negotiate 3.5%. On the other hand, Swedish and German design guidelines recommend vertical curve radii of 6400m and 10000m, respectively, at 125mph. Tighter curves can be used at lower speeds.

Note that some of the existing road underpasses may have been designed for just two tracks, just like those up in San Carlos. The bridges for the additional tracks on either side may therefore have to be elevated a little to maintain vertical clearances for tall road vehicles. I've allowed up to 2' difference in elevation at these points, which should be plenty. The upshot is that the inside and outside tracks would run at different elevations in a number of locations, limiting where the extra-long turnouts for baby bullet operation at 90mph could be placed.



The minimum vertical clearances are spelled out here: 24'3" for the Caltrain/UPRR tracks and 22'6" for the HSR tracks. Note that there is no need for an additional 1'3" electrical clearance in this case as the HSR tracks are not ever supposed to be used for AAR plate H freight cars. I assumed an additional 4' would be needed for the support structures of the short (75') road bridges at rail underpasses, with the additional option of support columns if fully-loaded 18-wheelers (80,000lbs GVWR) are to be permitted.

The Google Map

I've crunched the numbers in a spreadsheet, without any spiral easements in this first cut. The whole thing has ended up resembling a very gentle rollercoaster.


View Larger Map

Churchill Avenue: Rail Underpass

Only between Embarcadero (an existing road underpass) and Churchill Ave (which should ideally remain at grade) in Palo Alto is the transition a really tight fit. Caltrain would remain limited to 79mph at that one location, which is not a problem since all of its trains stop at University Ave anyway. HSR trains could run at 125mph (Swedish rules) or have to slow down to 103mph (German rules) - the difference stems from the passenger comfort thresholds maintained by these national railroads, rather than safety considerations.

Palo Alto Avenue: Road Underpass, Chicane

The Palo Alto Ave (Alma St) grade crossing is located between San Francisquito creek and the University Avenue Caltrain Station. Since both of those needs to be negotiated at grade, a deep road underpass is unavoidable in the context of this scenario. Given the proximity to the delicate root system of the venerable El Palo Alto coastal redwood tree, moving the road crossing south a little bit might be worth considering. That might also mitigate the impact on the connection for the eastern part of Palo Alto Ave. The 100-year-old railroad bridge across the creek should be replaced for safety reasons. Its replacement should support four tracks at grade and be located further from the tree, to protect its roots during construction. Worst case, the tracks could run on a low viaduct (1-2') to avoid exerting any pressure on the root system at all. The resulting crawl space could be filled up with loose earth if desired.

A fringe benefit of moving the tracks will be that the curve radii at the north end of the Palo Alto chicane will be eased somewhat. Doing so at the south end would also be appropriate, if the land can be obtained at reasonable cost. Easing the chicane would avoid a much more intrusive rectification of the Alma/University grade separation. Leaving the chicane in place would force express trains to slow to about 85mph, adding a full minute to their SF-SJ line haul time. If CHSRA selects Palo Alto University Avenue for the mid-peninsula HSR station, at least one straight 400m (1/4 mile) platform will be required, forcing a more significant redesign of the alignment. Both Redwood City and Mountain View are viable alternatives.

Honorable Mentions

In several locations, creeks and storm drains would have to be diverted underneath the tracks. In at least the latter case, regular cleaning would be required to prevent a build-up of debris and a risk of local flooding on the upstream side.

From north to south:

• in Redwood City, the section between Woodside Rd and 5th Ave should remain at grade on account of the existing grade separations, the Dumbarton wye and the Hetch Hetchy aqueduct that provides the peninsula with drinking water.
  
• in virtually all of Atherton and Menlo Park, the tracks would run in a deep trench, an implementation both cities requested of CHSRA.
  
• in north Palo Alto, tracks would run at grade everywhere except for the rail underpass at Churchill. This may or may not avoid conflicts with a toxic plume and an emergency aquifer, I'm not sure where they are located exactly.
  
• in south Palo Alto, both E Meadow and Churchill would remain at grade.
  
• San Antonio Caltrain station would still be at grade as well, but HSR tracks there would have to run underneath the Caltrain platform(s), as both the ROW and the San Antonio overpass are too narrow to support four tracks plus two platforms. That means a pedestrian overpass will be needed to reach the platform(s) - not much of an eyesore considering it will be right next to the road overpass. Also, the enclosure could be narrower between Charleston and Rengstorff, since only two of the four track would rise back to grade level. That would leave scope for bike/pedestrian paths, trees or elongated shallow water features at grade level, with spectacular lighting effects.
  
• in Mountain View, Castro Street and VTA light rail tracks mean that Caltrain/UPRR and HSR will need to run in a trench. Rengstorff Ave is a poor candidate for a road underpass, so the caltrain/UPRR tracks would remain underground for a total of ~2.2 miles. HSR tracks would run in a deep trench all the way from E Meadow to just north of 237.
  

HSR station in Mountain View?

The anyhow needed long trench in Mountain View would open up the possibility of an underground HSR/Caltrain station there. The city has recently requested that CHSRA study the possibility. IMHO, it might actually be a lot easier to put one there than at University Ave in Palo Alto. The Arroyo del Agua creeks would make an elevated alignment preferable in Redwood City, so an HSR station there would dominate the skyline.

In Mountain View, the Caltrain ROW could be widened underneath Central Expressway, with temporary lane closures during the construction period. Platforms would be reached via not one but three pedestrian underpasses, on account of the 1/4 mile HSR platforms. These would be two levels down, connecting West Evelyn to Willowgate. In the long run, the greatly enhanced property values on the far side of Central Expressway might merit rezoning for mid-to-high-rise mixed-use developments. Bike grooves next to stairs are always highly recommended in pedestrian underpass designs.

VTA light rail would remain at grade but be upgraded to dual tracks, with the option to extend service out to Rengstorff. This would be at the expense of the linear park feature but serve the senior center and create some room for overnight parking. A new line from Mountain View to Alum Rock would be possible, as would stairs/elevators from either Caltrain or HSR directly to the VTA platform(s).

In addition, a new streetcar loop service based on ultra-low floor (ULF) rolling stock could connect the downtown area (popular lunch destination, candidate for a small pedestrian zone?) to Shoreline business park/amphitheater with a yard east of Crittenden Lane. If the VTA line is extended, tracks for the two services would cross at right angles on Castro Street.



Most buses could continue to stop at W Evelyn, though city traffic planners could leverage the pedestrian underpasses to make auxiliary stops on the far side of Central Expressway (Willowgate, Moffett) potentially viable. A southbound bus lane from Rengstorff to just past the VTA turnoff on top of the tracks could also help avoid congesting in the downtown area.

Vitrine Entrance/Exit

Given the no doubt hefty premium an enclosure/trenching and a linear park would command, it's very likely that some peninsula cities will choose an uglier but cheaper option for HSR implementation, e.g. a Japanese-style viaduct with sound walls. However, the transition from open to enclosed track sections will be much like a tunnel entrance and should therefore be sloped and beveled to minimize any impact on the lateral stability of the trains and tunnel boom. The following example illustrates the residual effect at 186mph. Please note that all of the sounds you will hear would be less pronounced at the lower top speeds (90-125mph) applicable to the peninsula.

The Mid-Peninsula HSR Station

One aspect of yesterday's extensive thread entitled "Of Lawsuits, Tunnels and Tall Trees" that I feel did not receive enough attention is the matter of knock-on effects of grade separation strategies and, that of where CHSRA will put the mid-peninsula station. Other than the tentative Hanford/Visalia/Tulare station, this is the only one that CHSRA has not nailed down yet.

Knock-On Effects of Grade Separation Strategies

In deciding which type of partial or full grade separation they want to see implemented, the mid-peninsula communities of Redwood City, Atherton, Menlo Park and Palo Alto need to negotiate not just with CHSRA but also with each other. Once HSR becomes operational, there will be three railroads in the peninsula corridor: Caltrain, HSR and Union Pacific. ACE and/or Amtrak (Capitol Corridor, San Joaquin, California Zephyr, perhaps even a Coast Corridor sleeper service from SF to LA until HSR is available) could conceivably seek limited trackage rights up to 4th & King in San Francisco in the future, especially if and when the old Dumbarton rail bridge is restored to active service. That means the grade separation solutions in the mid-peninsula must also consider the need for turnoffs toward that bridge at the border of Redwood City and Atherton.

Serving everyone's needs requires that the gradients of at least the Caltrain tracks be kept low enough for freight trains (2.2% max) and, that all stations be on level track sections. Keeping everything at grade achieves this nicely, but it would also make full grade separation of the corridor more expensive and intrusive for properties adjacent to both the tracks and the cross-roads. That means it is not technically possible to elevate tracks in Menlo Park and not do it in downtown Palo Alto as well. Likewise, you cannot run tunnels under just downtown Palo Alto. The impact of the level at which tracks will run near the San Francisquito creek extends as far north as Redwood City and south to at least Oregon Expressway in Palo Alto, if not further.

CORRECTION: Except for deep tunnels under San Francisquito Creek, it appears there is in fact enough run length to accommodate a mix of grade separation solutions without turning the alignment into a roller coaster (h/t to Clem).

The Port of San Francisco has asked Caltrain to enable the operation of extra-tall AAR plate H freight cars, e.g. for transporting imported cars stacked not two but three high. It may be a serious case of the tail wagging the dog, but this wish might nevertheless be granted, e.g. as part of a grand bargain with UPRR on an ROW deal for SJ-Gilroy or, with the city of San Francisco on CHSRA/JPB contributions toward the DTX tunnel to and trainbox under its new showcase Transbay Terminal Center.

The overhead catenary system would have to provide not just physical but also electric clearance for plate H freight trains. The latter refers to the minimum vertical distance to the 25kV overhead catenary system that is required to avoid electric arcing (i.e. short circuits). This is especially critical at overpasses and in tunnels.

Any new long covered trenches or tunnels in the corridor might therefore have to be taller than required for Caltrain and HSR alone. Extensive undergrounding would also introduce another safety concern, as diesel-powered freight trains would need to run through several underground stations. EPA is tightening emissions regulations for remanufactured and new diesel locomotives, but all California rail operators have large numbers of dirty legacy units.

UPDATE: Retrofitting diesel locomotives with pantographs to avoid diesel emissions in tunnels is possible, but someone - e.g. the cities demanding that tracks be put underground - would have to pay for that, in addition to the much greater cost differential for a drilling four long, large-bore tunnels in the first place.

HSR Station Options

In addition to track work, the city that gets the mid-peninsula station will have to deal with the mixed blessing of becoming a regional transit hub. The primary challenge is figuring out how to manage - or better yet, avoid - additional car traffic by offering connecting transit and bicycle infrastructure, while eliminating free parking in the station environs. Below are maps that showcase the kinds of issues urban planners will have to deal with when HSR comes to their town.

Officially under consideration are Palo Alto and Redwood City. The former already generates more Caltrain traffic than San Jose. The latter is arguably better located for (connecting) service to and from from the East Bay, though that argument has been weakened by the decisions in favor of Pacheco Pass and the BART extension to Santa Clara.

Nevertheless, since there will be no HSR service between San Jose and Oakland in the foreseeable future, bus feeder services across the Dumbarton road bridge will have to be offered to avoid excessive additional traffic near the station areas. Another complication is that both candidate locations are located near shopping centers that offer ample free parking, intended for use by their customers. It is entirely possible that HSR passengers arriving by car would abuse these parking lots. One possible workaround is to always require motorists to pay for parking near the HSR station. Retail outlets would then validate the first hour or two for customers that spend above a threshold amount. Any surplus would be used to help subsidize local and regional transit services, which after all bring in not just rail passengers but also customers from further afield.

In addition to bus or streetcar services and for-fee car parking, Caltrain/HSR combo stations need to provide ample for-fee parking for bicycles - preferably guarded or based on biketrees to curb theft and save space.

The chosen host city should also provide safe bicycle access routes, as is common practice in e.g. Houten (Holland). Bicycles are emissions-free and use road space more efficiently that four-seater cars that are - let's face it - most often used to transport just one or two persons. Cycling therefore ought to be a popular way to catch any type of train, especially in summer when air quality is at its worst and gasoline at its most expensive.

City bikes with electric assist systems, already all the rage in China and parts of Europe, greatly increase the bicycle catchment area for train stations, in terms of both distance and terrain. It may even make sense for cities and passenger rail operators to encourage the purchase of folding models, possibly with electric assist, as these can more easily be stowed on trains and even, recharged. That would increase ridership and reduce demand for bicycle storage.

Another option are fleets of sturdy conventional bicycles that people can rent at no or very low cost, e.g. Velib' in Paris (France) or CityBike in Vienna (Austria). However, their success depends largely on high population density and flat terrain, a combination in short supply in California, though Palo Alto might qualify.

To illustrate possible solutions for the candidate locations for the mid-peninsula HSR station, I have prepared three exploratory maps. These do not reflect any official plans from any agency or city.

Note that these do not show the details of the station layout, e.g. side vs. island platform(s). The Caltrain HSR Compatibility Blog is a more appropriate venue for those. All I intend to highlight here is the need to accommodate four tracks, of which at least two must have two full-length (1/4 mile) level boarding platforms. Even if these are not fully built out right away, the space for them must be reserved up front, as must adequate room for pedestrian flow into and out of the station on both sides of the tracks.

Keep in mind that CHSRA could still decide to cancel its plans for a mid-peninsula station altogether in the context of the project-level EIR/EIS for this segment of the HSR route.

Option 1: Redwood City

View Larger Map

Note the existing Sequoia Station's proximity to a large shopping center and the city's main street, Broadway. The map also shows the convenient access to the business park at Network Circle and the Dumbarton bridge beyond it, as well as the turnoffs for future commuter rail service across the bay.

The bus route to Union City is indicated in orange. A new bus terminal next to the station could feature a publicly accessible green roof that would serve as an additional small park. The building could feature a second story with transit-oriented offices or else, support services for transit users/shoppers: a post office, a supermarket, dry cleaning, a day care center with for-fee reservation by the hour etc. Just for kicks, I also sketched (in red) a streetcar route that would link the station to several business parks in the area. There is a legacy rail ROW out to Seaport Blvd, but otherwise this is just an crazy idea of mine.

Option 2: Palo Alto

View Larger Map

Note the proximity to Stanford University, Stanford Shopping Center and the city's main street, University Avenue. The latter has already been grade separated against the railroad tracks as well as Alma St. and El Camino Real (see Focus On: Palo Alto). Both the rails and Alma St. were moved west some 85 feet to ease construction of the underpass. The resulting chicane would prevent HSR express trains from passing at 125mph. The existing station building will also have to be moved or replaced when the alignment is straightened out again. That means the Alma/University interchange will also have to be extensively modified unless the rails are moved into very deep tunnels with sufficient overburden at the underpass, which would open up a can of worms (see above).

If the rails remain above ground, it might make a lot of sense to leverage two of the existing connectors between the two roads to return Alma St. to grade level, but with a chicane in the other direction. The space in-between would be used for modified turn-offs into and out of the underpass.

In addition, the map shows a more radical idea that is not at all essential to HSR operations but in keeping with the transit-oriented spirit of the project: converting the section of University Ave. between the modified Alma St. and Webster St. into a pedestrian zone with al fresco dining etc. A single traffic lane down the center would be retained for vehicles with a permit, e.g. police, fire, ambulance, sanitation, handicapped transport and delivery trucks at certain hours of the day. Normally, it would be reserved for bicycles. All of the parking spots would disappear, motorists would need to make do with the parking lots along Lytton and Hamilton. Local traffic, possibly including a courtesy shuttle to the Caltrain/HSR station, would be routed around the pedestrian zone via these roads plus Webster and Alma. The European experience shows that shopkeepers' fears about losing foot traffic are misplaced, as shoppers actually flock to pedestrian zones within easy walking distance of transit stops and/or parking.

Vehicular through traffic would be encouraged to use the existing one-way express streets Homer and Channing, located several blocks south-east of University Ave.

Another feature of the map is a bus terminal located next to the station. An existing nearby restaurant could be relocated to the second floor there to make room for a nice plaza in front of the station, for drop-off/pick-up and taxi waiting service. As in Redwood City, the bus terminal building would feature a green roof, part of which would be used for al fresco dining in this case.

Also note the optional two-story car park at the north end of the station platforms, with a publicly accessible green roof to replace the soccer pitch and corner park that would be lost during construction. Alternatively, capacity could be added across the street at Stanford Shopping Center by adding a second story there, iff Stanford Shopping Center is amenable to that.

The final feature worth pointing out is the red area opposite El Camino Real from the station. The land is owned by Stanford University, which could decide to develop it for a transit-oriented hotel-and-conference center for visiting academics, cultural venue and/or affordable housing for graduate students. This is optional and not at all essential for the success of the HSR station.

Bonus Option: Mountain View

View Larger Map

This city is currently not under consideration for the mid-peninsula station, perhaps because that would give Santa Clara county three stations vs. just one for San Mateo county. Nevertheless, the location may be worth considering for three reasons:

a) VTA Light Rail already connects Mountain View to the "Golden Triangle" of Silicon Valley, a collection of high-tech businesses in the area bordered by I-101, 237 and I-880. The existing light rail track(s) will have to be moved to permit construction of two dedicated HSR tracks - if not up front, then definitely at a later date. Since the light rail approach to the station is single-track, one option would be to move that to the median of Central Expressway, terminating in Stierlin Rd. A pedestrian overpass would facilitate access to the train station.

b) The location is close to several major highways: I-101, Central Expressway, 85 and 237 plus, the area's largest employment and entertainment cluster - Shoreline - is near the shortest route to Dumbarton bridge. That means Mountain View arguably has a larger catchment area than even Palo Alto, which may explain why it already attracts almost as much ridership on Caltrain.

c) The city of Mountain View has been pro-active in planning ahead for the arrival of HSR tracks (h/t to Clem Tillier).

The town's main street, Castro, currently features a busy grade crossing. Existing overpasses in the area preclude elevating the tracks and, a deep underpass would be disruptive to the station and other properties near the intersection. The map therefore shows Mountain View station remaining at grade with the crossing permanently closed! A drastic step, to be sure, but one that may be required for HSR even if its trains end up just passign through.

To compensate for the loss of access to Central Expressway in particular, traffic would be re-routed via N Shoreline, W Evelyn and Whisman. Also shown are alternative access routes to and from 85 and 237 that skirt residential areas. With road space at a premium near the station, traffic is already constrained northbound at the station. Note that the direction of traffic flow around the bus stop circle might have to be reversed. However, there is no room right next to or across Central Expressway from the station for a bus terminal, as in the other two locations.

Also shown is the option of turning three blocks of Castro St, a popular local destination for lunch, into a pedestrian zone with traffic routed around it via side streets. Note that there is no large shopping mall near this station.

Finally, note the existing bike lanes and dedicated path out to Shoreline business park (Google et al), amphitheater and lake. The path extends all the way to Palo Alto airport. Unfortunately, N. Shoreline is too narrow to permit extending VTA light rail all the way out there, so concertgoers arriving by train will have to hop on the bus across to Union City instead. It should use the frontage road to avoid I-101, which is often congested.