21 December 2008

Focus on: Palo Alto

Palo Alto was founded in 1887, several decades after the railroad tracks were first laid between San Francisco and San Jose. The town grew and filled in around the railroad tracks, and now has one of the busiest stations on the Caltrain line (shown at right; credit cdent), second only to San Francisco. Palo Alto today handles nearly 50% more riders than San Jose's Diridon Station, vaunted as tomorrow's "Grand Central of the West." Palo Alto is also a major stopping and transfer point for Caltrain's Baby Bullet express trains. That is why Palo Alto, along with Redwood City, is under consideration by the CHSRA as the possible location for a mid-peninsula high speed rail station.

Whether or not this new station is located in Palo Alto, the CHSRA's choice of the Pacheco Pass alignment via San Jose means that high speed trains will run through the town along the Caltrain right of way, which will be widened to four tracks and electrified.

The following sections of this article consider HSR impacts to Palo Alto roughly from north to south. With no further introduction, let us scroll southwards:

San Francisquito Creek

The CHSRA's environmental impact documents describes the tracks crossing into Palo Alto at grade over the San Francisquito Creek, with two tracks on the existing historic (relic?) truss bridge, and two new tracks added to the west. The famous El Palo Alto tree, California Historical Landmark Number 2 and the landmark for which the town is named, is thus spared any direct impact. Perhaps an even better idea would be a new 4-track deck bridge, to get rid of the truss that crowds out the historic tree. (By the way, the San Francisquito creek area was also where ground was broken for the peninsula railroad on May 1st, 1861.)

The Palo Alto Ave. (a.k.a. Alma) crossing right after the bridge would become an underpass, and perhaps not an easy one to build considering the proximity of the San Francisquito aquifer.

The right of way is 100 to 120 ft wide in the area of the creek crossing (see ROW map), leaving plenty of room for four tracks.

Palo Alto Station Area

The existing Palo Alto depot, with its distinctive "Streamline Moderne" style, was opened in 1941. It is the third depot building that has existed at this location. The station once had three tracks running through it; today, the middle track has been dismantled, leaving a wide space between the two platforms. The platforms and pedestrian underpass were recently renovated by Caltrain, as part of a $35 million improvement project.

The impact of high speed rail on the Palo Alto station area will depend on whether or not the town becomes the mid-peninsula HSR stop. However, regardless of this outcome, the station area will require some reconfiguration to accommodate high speed trains passing through the station at speeds of 125 mph (200 km/h), as planned by the CHSRA.

The Palo Alto Chicane

The existing 1940s station, along with the underpass for the town's main street, University Avenue, were built alongside the tracks that previously existed there, presumably to allow uninterrupted service during construction. As a result, the entire station is offset laterally to the west of the straight alignment of the peninsula tracks; the northbound track is offset by 60 feet, and the southbound track by 85 feet (shown in the photo at right by ibison4). While this arrangement is fine for the speeds practiced today, it will look like a chicane to an approaching high speed train. At speeds of 125 to 150 mph (200 to 240 km/h), curves must have radii of at least 1 to 1.5 miles (1800 to 2300 m), with adequate spiral easements entering and leaving each curve. While there is enough room to run such curves through the present footprint of the Palo Alto station (see map below for approximate property limits), it will require a total reconfiguration of the tracks through the station.

At 150 mph, the maximum lateral track offset comfortably achievable within a run of 1500 ft (about the room available on each end of the existing station) is about 20 ft. At 125 mph, it is about 30 ft. Both of these values are much lower than the present lateral offset of 85 ft (on the southbound track), which would require a train to slow to about 85 mph (135 km/h). It may seem easy to slow down a bit through Palo Alto, but it would cost about a minute (over half a percent) on the overall SF - LA run times. If every trouble spot from San Francisco to Los Angeles cost a minute, HSR would never be possible; therefore, just like San Bruno's sharp curve, today's Palo Alto station alignment should be considered a serious obstacle to HSR on the peninsula.

To reconfigure the station for higher speeds, it is possible to (a) straighten the station by shifting the tracks closer to their ancestral straight-through alignment, as depicted in an effortless hand sketch in the CHSRA's "station fact sheet", or (b) make the tracks bow out westward on a smooth and continuous curve, which requires building gently curved platforms. Due to the overall width required for four tracks and two platforms, parking will need to be moved elsewhere from the east side of the station, and the Alma St. overpass that runs parallel to the tracks will need to be completely reconfigured. (This overpass, as it exists today, is built on railroad land.) The existing northbound platform would have to be demolished; however, the money recently spent to rebuild it is but a drop in the HSR bucket.

With the track alignment issue taken into consideration, there are basically two scenarios for the Palo Alto station area, where railroad land is abundant (see ROW map).

HSR Station Scenario

If Palo Alto chooses to become the mid-peninsula stop for high speed rail, the impact to the station area will obviously be greater. However, an expanded station would also create opportunities for more frequent and efficient Caltrain service, in addition to long-distance HSR service. It would become possible to operate timed, cross-platform connections between Caltrain local and express trains.

The CHSRA shows in its station fact sheet that Palo Alto would be rebuilt with two island platforms located between the inner and outer pair of tracks, a configuration that is favorable to cross-platform transfers. One is left to wonder why this configuration was not chosen for Millbrae as well. The basic cross-sectional dimensions from this station fact sheet are reproduced in the map below, with curved tracks bowing out such that the curve apex coincides with today's southbound track. The two island platforms are curved as well, but their radius of 3.5 miles (yes, miles!) might as well be straight for purposes of platform boarding and alighting. A more accurate version of this map is also available by downloading the original KML file into Google Earth. Note that if the existing depot building were demolished or moved, it would in principle be possible to shift the curve apex a further 15 meters (50 feet) west of the existing southbound track, possibly relieving some of the design constraints on the Alma / University road overpass.

View Larger Map

The station would require a new parking garage, with easy access from El Camino Real. The nearby El Camino Park would not be affected.

No HSR Station Scenario

If the mid-peninsula HSR station is built in Redwood City instead of Palo Alto, the station would be expanded to four tracks flanked by two outside platforms, with no platforms on the center high-speed tracks. Since there is only enough room for three tracks through the existing station, the northbound platform would most likely be moved (i.e. demolished and rebuilt), providing room to straighten the center express tracks and add the fourth track.

One design consideration, among many, is whether or not to preserve the existing three track alignments over the University Ave. underpass, only two of which are currently in use (as shown in map above). Shifting these track alignments may have impacts on the load-bearing structure of the underpass. (Update: there are actually four track ways across the overpass... one of them sits under the southbound platform, and it's unclear if it was ever used.)

No matter what happens at the Palo Alto station, expect a big rearrangement on the east side of the station, with serious impact to the Alma St / University Ave overpass. Given that major reconstruction will be required either way, Palo Alto ought to give serious consideration to "biting the bullet" and building the HSR station.

Bike Path

An existing bike path along the west side of the tracks, from the Palo Alto Medical Foundation to the Churchill Ave. crossing, is partially built on a revocable easement of Caltrain land (see ROW map). Widening to four tracks will require the bike path to be removed from this location. The existing bike tunnel would also have to be reconfigured. From approximately this location until California Avenue, the Caltrain right of way is narrower than 100 feet. From the station to Churchill Ave, the ROW is 85 feet wide.

Churchill Ave Grade Separation

The CHSRA plans a split grade separation for the existing Churchill Ave grade crossing, located behind Palo Alto High School. Refer to Volume 2, Appendix D, page 5 of the Bay Area EIR/EIS. The preliminary concept for this split grade separation would raise the tracks by 15 feet (4.6 m) on a retained embankment (i.e. an embankment with vertical walls) to pass over Churchill Ave, with the latter lowered by about 6 feet (1.8 m). It is difficult to lower Churchill further due to the proximity of the intersection with Alma St.; the impact of lowering the intersection must be traded off with the impact of the retained embankment.

Due to constraints on the vertical curvature of the tracks for planned operation at 100-150 mph, the approaches for a 15-foot raised embankment would necessarily be long, on the order of 400 m (1/4 mile) on each side of the overpass. Shorter approaches would make passengers feel uncomfortable as the train crested over the top. This is why the area behind Palo Alto High School as well as a good portion of Southgate would be affected by the long Churchill grade separation embankment described in the CHSRA's documents (although the 3% ramps described in Volume 2 Appendix D are not feasible).

Architect and local resident Jim McFall has produced video renderings of what this grade separation might look like, although he modeled it a full 21 feet higher, rather than the 15 feet assumed in CHSRA documents. It is likely that Churchill could be depressed ~6 feet from the current track level.


Southgate is a neighborhood that abuts the western edge of the tracks, just south of the Churchill Ave crossing. This area is one the narrowest portions of the railroad right of way owned by Caltrain (see ROW map). The overhead view at right, superimposed with a scale ruler, shows about 75 feet of horizontal clearance between the back fences of houses on Mariposa Street and the Alma Street curb on the other side of the tracks. Eminent domain takings, even for as little as 10 feet into these properties, might be necessary to build four tracks through the area without constraining Alma St. This would be in addition to the impact of the raised embankment used to cross Churchill Ave.

As was described in a post about electrification, it would in principle be possible to squeeze the four-track right of way into an overall width of 75 feet, where no additional clearance exists. Whatever happens, it's a tight fit.

Peers Park

The railroad right of way is a mere 60 feet wide alongside Peers Park. Four tracks will likely require an encroachment of at least 15 - 20 feet into Peers Park, and the removal of all the mature trees along the railroad edge of the park. Immediately after the park, the railroad right of way returns to a more generous width of 95 feet.

California Avenue Station

The HSR tracks are expected to pass the California Ave. area at grade level. The station was recently rebuilt by Caltrain, under the $35 million Palo Alto stations project. The platforms and underpass would have to be partially demolished and rebuilt to make room for four tracks.

South of California Avenue, the right of way has a width around 100 feet or more. For details, see ROW maps for mileposts 31-32, 32-33, and 33-34.

Meadow and Charleston Grade Separations

While Palo Alto has just four grade crossings that are not yet grade separated, two of them, Meadow Drive and Charleston Road, are located just 1/3 of a mile (500 m) apart at the south end of town. (see also ROW map). The CHSRA documents describe a 7 foot (2.1 m) retained embankment at this location. This would require lowering each road by 14 feet, with the consequence that the nearby intersections with Alma St. would be lowered as well. Ramps for a 7-foot embankment would need to be about 1000 feet (300 m) long on each end for operation at 125 - 150 mph.

The tracks would return to grade level before San Antonio Ave.

Vertical Track Profile

The vertical track profile is the level of the tracks (raised above grade, at grade, or below grade). Working from Caltrain track survey data, here is the profile of Palo Alto, with the vertical scale greatly exaggerated: (click to expand)

HSR will significantly modify this profile. A detailed discussion of the vertical profile options for Palo Alto, including what can and can't be done with the tracks, is written up in the Shape of Palo Alto.

The Tunnel Idea

Some members of the Palo Alto community have suggested putting the tracks underground through most or all of Palo Alto, removing the barrier formed by the existing tracks and opening up the former railroad land to development of housing and parks. This idea was the subject of a cover story by the Palo Alto Weekly. The proponents of the idea suggest that HSR funding might be used to build such a tunnel. However, since the benefits of the tunnel would be solely to local residents (and not to users of HSR) it is probable that Palo Alto would need to foot most of the bill for a project that promises to cost hundreds of millions, if not billions, of dollars--especially if Alma St. traffic and Caltrain continue to operate during construction.

In conclusion, it will be interesting to watch Palo Alto's reaction to HSR impacts. The majority of residents voted for Proposition 1, and the city council supports HSR in principle, but the impact on affluent neighborhoods and the famed "Palo Alto Process" should make this an interesting show to watch.

NOTE: This post will be updated continuously, as warranted by additional information or new events relating to Palo Alto.


  1. Perhaps city planners and CHSRA need to remember that while HSR must be grade separated wherever speeds in excess of 125mph are planned, doing the same for Caltrain is optional - though highly desirable.

    Worst case, it would be legal to stack HSR tracks on top of existing Caltrain tracks and retain grade crossings for the latter, preferably with FRA quiet zone regulations met. This concept does not work where there are already overpasses and, it's not pretty. However, it would avoid having to widen the ROW in e.g. parts of Palo Alto.

    I'm not saying Caltrain grade crossings should be retained, just that it's a legal option. Might come in handy if city officials prevaricate.

    As far as the University/Alma interchange is concerned, I think the appropriate solution would be to eliminate the connector loops and run Alma straight. High Street north of University should become a a one-way street northbound so motorists can drive around the block there. It may well be necessary to lower University west of High so Alma can be straightened. This would entail significant disruption to a major traffic artery, but IMHO everything else would be a cloodge. That chicane is not acceptable for HSR express service.

    Note that regardless of whether Palo Alto or Redwood City is chosen for the mid-peninsula station, HSR trains can be as long as 1320', so those island platforms will need to be quite long. It's also advisable to plan for at least three pedestrian underpasses to provide access to them, though only the one in the middle would need an elevator for the disabled.

  2. What's your thoughts on palo alto possbily pulling off something like berkeley and bart back in the day - tunneling or cut & cover for the line through all or part of the length of town?

    Re: http://www.paloaltoonline.com/news/show_story.php?id=9435

  3. @ Michael J -

    I think putting tracks underground in Palo Alto would be quite difficult, for two reasons:

    (a) with so little gradient between the Caltrain ROW and the Bay, any underground alignment would have to pass underneath storm drains, San Francisquito creek etc. That almost certainly means tunneling rather than cut-and-cover.

    (b) any deep alignment will also have to extend into Menlo Park, perhaps Atherton. While those cities would probably welcome such a move, the cost would be quite staggering. CHSRA has a certain amount budgeted for the SF-Gilroy section of the network, anything fancier would have to funded at the city and county level. Even given that these cities are quite wealthy, it's not clear that their residents would be willing to take on billions in debt just to put the rails underground.

    After grade separation and electrification, there will be no more horn blowing nor any tailpipe emissions, so two of the most serious objections to heavy rail will be eliminated. Rail-wheel noise is reduced because electric traction permits recuperative braking, so mechanical brakes need only be applied in emergency situations.

    That means the surface roughness of the wheels isn't compromised, which helps keep down rail-wheel noise. However, aerodynamic noise is proportional to the cube of velocity at high speeds, one reason HSR trains have specially shaped noses. It's not too bad at ~125mph, but still an issue early in the morning and late at night.

    It might make sense for Palo Alto and other cities along the peninsula to focus on noise mitigation, preferably at source. Why not spend some money on a research grant or two for Stanford so it can develop some technical expertise in this area, then lobby CHSRA to give noise aspects high priority in trainset vendor selection.

    Worst case, there are always sound walls, especially for residents whose properties are immediately adjacent to the tracks. They have to be quite high to be effective, though.

  4. Michael J, thanks for reminding me of that; I added a short paragraph about it with a link to the PA Weekly story.

    My opinion is that it's not a good idea... it boils down to a YIMBY project (Yes In My Back Yard) that has the potential to blow up HSR budgets and schedules. It violates the KISS principle (Keep It Simple Stupid).

    If Palo Alto has the political and financial means to do it (which I strongly doubt) they should pay for detailed studies to get a better idea of the incremental cost.

  5. I suspect that encroaching on the Alma right-of-way (and the ROW of the other roads directly adjacent to the rail line in various places) is probably the least worst option for track and stations in many spots along the peninsula.

    There are plenty of parallel roads, folks -- and you only need one lane for local access.

  6. I read somewhere that HSR will not travel at speeds over 125mph on the caltrain tracks. But wont it travel slower at certain points?

  7. Also it may end up that HSR and Caltrain share the current 2-4 track layout with some added 4track sections as the cost and outcry may be too much. would 110mph segment really do that much damage to the overall schedule? it sure would save alot on the overpases

  8. @anonymous 18:07

    The cost of not doing it right will be far worse than the cost & outcry of quadruple tracking the entire peninsula. HSR and commuter rail are like oil and water; trying to mix them on the same tracks will be an unmitigated disaster for both.

    That being said, Caltrain express trains can benefit from "borrowing" the HSR tracks to overtake locals... but the underlying assumption is that 4 tracks must be available to do that.

    Palo Alto, Menlo Park and Atherton are some of the most affluent areas of the railroad right of way, and that's where the NIMBY action will get hottest. However, now that all the political planets are aligned towards Pacheco Pass, I don't think those peninsula towns will have much power to stop or slow the bullet. One thing is sure: it'll be quite a show... pass the popcorn.

  9. In half-hearted defense of the Millbrae design:

    Palo Alto makes sense for timed transfers in the NB direction because it can collect local passengers from Santa Clara, Lawrence, Sunnyvale, Mtn View, San Antonio, and Cal Ave. In Feb 2007 these stations had 7,064 combined boardings.

    Millbrae makes less sense for timed transfers in the SB direction because it can collect local passengers from only 22nd St, Bayshore, South SF, and San Bruno. In Feb 2007 these station had only 1,969 combined boardings, and almost half of these were at 22nd St (which is served by every reverse Baby Bullet and 2/3rds of reverse peak limited trains).

    That said, unless it is substantially more expensive to build the island platform configuration, you might as well do it because it leaves the timed transfer option open and has no drawback vis a vis the side platforms.

  10. Maybe sometime some decade somebody will get the idea that mixing HSR with local service for an inch further than physically necessary is completely insane and completely without any precedent anywhere in the world and that maximizing impacts on the most expensive to engineer parts of the line in the backyards of the most affluent abutters in the state was something that would only be chosen by somebody utterly corrupt and on the take.

    It will take a few billion of disappearing public money (A Christmas Miracle! watch me turn cash into consultanies!) before anybody starts to cotton on.

    And 200+kmh anywhere north of San Jose?
    It's not going to happen, because it doesn't happen anywhere even remotely comparable. (Shinkansen fan boys note: I've ridden the same trains (or more likely, watched the same youtubes) as you, yet somehow I've gained the impression that San Bruno and Menlo Park and San Mateo and Mountain View aren't yet quite perfect Japanese mega-conurbations.)

    There is simply no possibly justification for any massive, disruptive ROW engineering anywhere between Redwood City and Santa Clara; this is all pure make-work, make-profit, make-enemies craziness.

    "Mistakes were made", as Judge Kopp can be overheard to say -- off the record -- of his enormous BART to Millbrae success.

    Quadruple tracks at 125mph all the from SJ to 4th&Townsend (the Grand Central of Soma!) by 2015! The Big Q says it can be done!

  11. Thanks to Richard M's comments, I have rewritten some of the material concerning the Palo Alto station alignment. I had wrongly assumed the platforms needed to be straight; with curved platforms, the track geometry problem is greatly relieved and it would be straightforward to run four 150 mph tracks through the existing station property boundaries. This is now shown in the map (and renders infinitely better by downloading the KML to Google Earth). The basic conclusion is still the same, however: the Palo Alto station tracks will need to be completely realigned.

  12. Platforms may not need to be straight, but they need to be *very close to* straight in order to minimize the platform-train gap (crucial for ADA accessibility).

    I suspect the curvature of 150 mph tracks may be small enough to satisfy the requirements, but I haven't actually looked -- it depends, among other things, on how long the individual train cars are. In any case, curvature at station platforms should be minimized to the greatest extent possible.

  13. To say that more clearly :-), the 3.5 mile radius curve would be pretty much perfectly straight as far as a 100 foot train car was concerned. But for a train car which was, say, a quarter of a mile long, it would obviously be a unpleasantly large gap.

    There's an interaction between the train design and the possible curvature in station tracks (and frankly in the envelope around curves on non-station tracks as well). I'm not sure how it actually works out with the standard models of HSR trains because I don't know the carlengths off the top of my head.

  14. Passenger train cars, whether high speed or not, are nearly always shorter than about 85 feet (26 m). The sort of curvature discussed here is not an issue.

  15. @ various comments:

    The Palo Alto ROW also includes a natural gas pipeline. I imagine the pipeline will be easy enough to relocate.

    Alma Street is already tight for space. The lanes are narrow and there is no emergency lane in the SB direction. If the tracks were sunk below grade then the Alma ROW could be widened. With below grade tracks, the underpasses at University, Embarcadero, and Oregon Expswy. would become surface intersections. Hopefully modern intersections could accommodate the traffic.

    To the south, San Antonio is an overpass. Currently the tracks go under San Antonio and begin to climb a grade to the point where they cross over the Adobe Creek. I can hear the freight trains at night rev up to climb the grade.

    The area around the Palo Alto station is an obstacle for cars and pedestrians. There has been talk of improving the pedestrian access between downtown, the medical center, the park, the Stanford Mall, and Stanford beyond the recent underpass near the Medical Center. Realigning Alma over University was discussed.

    I am not sure but it seems logical that a creek or waterway such as San Franciscito, Matadero, or Adobe, could be made to flow under the tracks below grade if a basin were built to let the water sink down and rise on the other side and continue down the waterway.

    Encroaching on Alma is not an option. Alma carries a lot of traffic as it is. The traffic seems to commute north in the AM and south in the PM but always has traffic both ways. After reading this blog I was thinking that they might be able to make Alma a one-way north in the AM and one-way south in the PM during HSR construction which would open up some room to let CalTrain continue to operate.

  16. An extreme case is to lump the railroad ROW and Alma easement together as a clean sheet design. Then what are the options? Make Alma a true expressway with residential frontage roads and have underground tracks? Room for park and ride? A bike path?

  17. Encroaching on Alma is not an option? Really? Alma carries a lot of traffic, sure, but I've never seen it backed up to the point of a traffic jam, even at peak commute times. And there are a lot of parallel streets that could pick up the traffic (El Camino, Middlefield, etc.).

  18. One point that is never mentioned is the bridge over Unversity Av. is set up for 4 tracks. It once had a sidding for the Palo Alto car that was added to one of the passenger trains. If you go under you can see the sapports for all 4 tracks. I once saw a picture of all 4 tracks.

  19. It is indeed mentioned, although not very prominently. I am doubtful that all 4 trackways could be used without violating minimum platform width or track spacing standards... and the unused 4th trackway is on the west side, furthest from the straight-through alignment. I wouldn't bet on it being useful.

  20. The forth track was never thru and would require the station to be moved. I just mention it because when Palo Alto was pushing a rebuild many years ago they used the argument that for 4 tracks you needed a new bridge. At that time for the speeds thay were listing by moving the station and then the platforms north 2 blocks you could have made it work and save about 250.000.000$ off what they had proposed. They full plan was as stupid as what you expect from Palo Alto and I have lived hear for 52 years. For HSR you will need a new bridge.