Optimizing the Midline Overtake

The most important piece of infrastructure required for "blending" HSR with Caltrain on the peninsula rail corridor is an overtake facility, basically a several-mile long stretch of up to four tracks that will enable faster trains to overtake slower trains.  Caltrain studies have shown that the best performance (measured by robustness to cascading delays) can be achieved with a midline overtake  from San Mateo all the way through Redwood City.  Preliminary engineering and environmental clearance for this infrastructure is now resuming, with the recent award of a $36 million contract by the CHSRA to engineering firm HNTB.

The baseline configuration for this overtake is described in Caltrain's blended operations analysis, and assumes rebuilt stations at Hayward Park, Hillsdale, Belmont, San Carlos and Redwood City with four tracks and outside platforms in the tried and true style of the 1930s Pennsylvania Railroad. High-speed trains would use the center pair of tracks to overtake slower trains on the outside pair of tracks, as shown below (click figure to enlarge):

For comparison, the figure also shows a better solution that ensures the highest level of punctuality for all trains using the corridor.  This optimized overtake configuration differs from the baseline configuration as follows:

• The slow trains run in the middle, so that disruptions to local commuter service (for example, when an incident blocks a track for hours) do not disrupt high-speed service when commuter trains are re-routed around the incident location.  This track configuration is known as Fast-Slow-Slow-Fast (FSSF) as opposed to the traditional SFFS.  Real world examples of FSSF can be seen in train cab videos from Sweden and Australia.
   
• All commuter stations are built with central island platforms.  This allows commuter trains to use either platform face without confusing passengers, and requires only one set of station amenities (shelters, elevators, escalators, stairs, ticket vending machines, PA systems, train arrival screens, lighting, benches, etc.) because there is only one platform.
   
• A major new interchange station at Redwood City, with four platform tracks and additional train storage sidings.  This station (described below) would serve as a transfer point for HSR, Caltrain and future Dumbarton trains, as well as non-rail transportation modes.
   
• A carefully planned future-proofed high-speed rail junction where the Dumbarton rail corridor meets the peninsula rail corridor, preparing for the inevitable arrival of passenger rail service across the Bay.

Here's how it would ideally play out.

Short Term: the San Mateo Grade Separation

Preliminary rendering of new
Hillsdale station with island platform

The next step in the decadal process of grade separating the peninsula rail corridor will soon begin in San Mateo.  A new $180 million grade separation project is in the final stages of planning for 25th Avenue (currently a grade crossing) as well as 28th and 31st Avenues (currently not connected).  Concurrently with this project, the busy Hillsdale station will be moved a bit north of its current location and turned into an island platform.

This project is caught in an interesting political bind.  There is on one hand a rush to complete it by 2019 before Caltrain's electrification project, to minimize disruptions to Caltrain service.  On the other hand, due to its strategic location, this project will form a key building block of the blended system with HSR, which still needs to be environmentally cleared.  It is a near certainty that this portion of the corridor will require four tracks to enable trains to overtake each other, but any attempt to design and build it as such is likely to run afoul of HSR opponents who will accuse the CHSRA of advancing their project through CEQA piece-mealing.

The southern San Mateo grade separation design will have to be very carefully considered to preserve the ability to add two additional tracks with as little disruption as possible.  Road underpass profiles and bridge abutments should be designed for four tracks, as should the elevated structure that will support the tracks.

The choice of an island platform configuration for the new Hillsdale station is either a sneaky way to build a wide four-track embankment in preparation for yet another new station with SFFS outside platforms, or is an excellent choice for FSSF because it allows future tracks to be added without rebuilding the station for a second time.  One hopes the station access (stairs, ramps, etc.) will be designed to allow the platform height to be raised easily from 8" to 50".  An intelligently designed San Mateo grade separation would atone for the terrible failures of the San Bruno grade separation, designed with great hostility towards higher speeds or additional tracks.

Medium Term: Redwood City HSR Station

Amsterdam Bijlmer (photo by tataAnne)
could just as well be the future
Redwood City train station.

While the CHSRA's plans for a mid-peninsula stop have been shrouded with ambiguity for several years, Redwood City stands out as a more optimal location for a new HSR station than Palo Alto or Mountain View, the other two locations in the running.  Unlike its neighbors to the south, Redwood City favors strong urban growth, has a large amount of railroad land available, and is reasonably well-connected to the existing road and transit network.  Redeveloping the antiquated but popular Sequoia Station shopping center would enable the construction of an elevated four-track station with plenty of capacity to support not just HSR but also Caltrain cross-platform connections and future Dumbarton service.

The station complex would feature two shared (HSR or Caltrain) 400-meter island platforms centered between Broadway and Brewster, easily accessible from both streets.  Bus connections would be conveniently located under the station. To the north of the platforms, a pocket turnback track would allow Dumbarton trains to reverse without fouling other traffic.  Similarly, to the south of the platforms, another pocket turnback track would allow southbound Caltrain locals to terminate in Redwood City before turning northwards again to serve the densely-spaced stations of San Mateo County, allowing Caltrain to serve more passengers with fewer trains and crews.  Thanks to the FSSF configuration, all this to-and-fro by commuter trains would stay well out of the way of HSR.

This would be a large train station and quite a tight fit (if you're curious about exactly how large and how tight, download this KML file into Google Earth to view the station footprint and track layout).  It would be a big change for Redwood City, but with a huge payoff: the tracks would no longer form a barrier through town, and the Sequoia Station shopping center would be merged with the station to form a gateway and a destination in its own right that is connected to downtown.  HSR service could make the city a very desirable location for business.  The new station could become the centerpiece of the ambitious revitalization strategy described in Redwood City's downtown precise plan.  But this idea is not without pitfalls, as the size of the station could be compared to plonking a couple of Nimitz-class aircraft carriers in the middle of town.  To use the tired slogan, it needs to be done right.

Medium Term: a New Fair Oaks Station

Approximate location of new Fair Oaks
station island platform, view to northeast.
Overtake would extend just beyond
platform to the right (south).

The key to reliable overtaking on a multiple-track railroad is to ensure that the average speed of the slower train being overtaken is sufficiently slower than the average speed of the faster overtaking train.  One of the ways of ensuring a good speed differential is to have the slower train make station stops that the faster train doesn't; each station stop is worth about 2.5 minutes.  Therefore, locating stations on the four-track overtake section is helpful.

This brings us to a lemon of a station immediately south of the midline overtake: Atherton.  Located in an area of very sparse population and jobs density, Atherton should be permanently closed.  This closure would come not only as a show of appreciation commensurate with the town's support of Caltrain modernization, but especially because census data shows clearly that Atherton is precisely where you would never place a train station.

To replace Atherton, a new Fair Oaks station should be built just 0.6 miles to the north, at the 5th Avenue grade separation.  The overtake section would be extended a bit southwards, just beyond the station, enabling locals to be passed while stopped at the central island platform that can be accessed from either side of 5th Avenue.  The new Fair Oaks stop would be equidistant from Redwood City and Menlo Park, and located in an area with very high population density that could support thriving ridership, in contrast to Atherton.

Longer Term: a Seamless Dumbarton Connection

Dumbarton rail has been an uncertain prospect for decades, with some political backing but insufficient funding.  While it may take another few decades for the money and the will to finally materialize, large concentrations of employment and the need for additional transbay corridor capacity make some form of passenger rail service inevitable.  The Dumbarton corridor also happens to be ideally suited for high-speed rail.

The key node is Dumbarton Junction, which should be reconfigured in such a way that trains can enter and leave the peninsula rail corridor swiftly and seamlessly.  This will likely involve a flyover track, enabling southbound trains to enter the Dumbarton corridor without crossing (and therefore blocking) any of the northbound tracks.  To minimize the altitude of the flyover, the Rte 84 / Woodside Road overpass would be turned into an underpass.  As for the Redwood City station, the fit would be quite tight with a 90-foot corridor width where the flyover track begins.

While the flyover may seem like an expensive solution to a problem we don't yet have, planning for it now (if not actually building it) will save money in the long run when passenger rail service grows.

Design Values

No matter how the midline overtake is ultimately configured, it must reflect design values that are clearly articulated.  One of these values should be compatibility between Caltrain and HSR.  It's not enough to talk about the "blended system" without actually taking the steps to make the two systems seamlessly interoperable, allowing any train to use any track to serve any platform.  This means no tracks can be dedicated to one operator at the exclusion of another.  Everything must be shared, including the platforms at the new mid-peninsula station.  This sharing contributes to another important value, robustness to service disruptions.  The fast-slow-slow-fast track layout is the key to ensuring that a commuter train delayed in Belmont won't create a statewide domino effect that eventually makes a train late in Los Angeles.  A third important value is future-proofing.  Infrastructure like the midline overtake will define what is possible (and not) for generations to come.  It would be short-sighted not to plan for a fast and seamless connection to the Dumbarton corridor, even if its future use isn't well-defined today.

The midline overtake is the key to an effective blended system.  When evaluating its design, ask yourself: is it compatible?  Is it robust?  Is it future-proof?

Primarily Two Tracks

Figure 4 from Caltrain's study, showing several possible locations for new overtake tracks.  Not all would be built.

In recent days, the high-speed rail Draft Revised 2012 Business Plan as well as the Caltrain Blended Operations Analysis were released to the public.  Both of these documents refer to the peninsula blended solution as a "primarily two-track" system, in the hope of allaying fears of massive eminent domain takings of homes and business-- fears that are largely unfounded, but fanned relentlessly by the local press and project opponents.

The confusion continues over what "primarily two tracks" precisely means, because neither agency seems ready to come out yet and state it in crystal clear terms.  The process still needs to unfold.  Luckily, enough data has already been published to allow a reasonably good reading of the tea leaves, down to the nearest tenth of a mile.

Phase 1 will be electrification, according to the memorandum of understanding currently being put in place by MTC and other parties.  This project already has federal environmental clearance and is very close to state environmental clearance, although a strong push will be made by opponents to subsume Caltrain's electrification EIR into the peninsula HSR project EIR, a document that will not be finalized (let alone litigated!) until 2015.  This phase of the project will not add any tracks, so the total length of quadruple track will stay as it is today (2 miles in Brisbane; 1 mile in Redwood City; 2 miles in Sunnyvale).

• Purpose: improves Caltrain, enables future peninsula HSR
• Time frame: 2013 - 2019
• Total miles of quadruple track: 5
• Grade-separated fraction: 61% (64 of 104 road crossings)
• Trains per peak hour per direction: 6
• Cities impacted by construction: none

Phase 2 will be a concrete viaduct through Santa Clara, completed at the same time as HSR reaches San Jose sometime in the mid-2020's, enabling a one-seat ride to San Francisco under the so-called "Bay-to-Basin" scenario.  If the CHSRA's grandiose plans (described in an October 2011 report to the legislature) are to be believed, this will entail building a massive double-decker station complex at San Jose.  A new four-track HSR station will hulk over the existing Diridon Station, perched on massive concrete straddle bents.  A more than 3-mile-long, 60-foot-tall viaduct will be constructed northwards, joining the existing corridor at approximately milepost 44.5, north of the Santa Clara Caltrain station.  Overpasses at Hedding and De La Cruz will be demolished and rebuilt as underpasses to make room for the new double-deck rail right of way.  Note that Caltrain's study considers this phase as part of the "baseline infrastructure" and therefore does not count it as additional tracks.

• Purpose: enable single-seat HSR ride to San Francisco
• Time frame: mid 2020's
• Total miles of quadruple track: 8
• Grade-separated fraction: 61% (64 of 104 road crossings) 
  
• Trains per peak hour per direction: 8 (6 Caltrain + 2 HSR)
• Cities impacted by construction: Santa Clara

Phase 3 will be the "short" mid-line overtake from 9th Ave in San Mateo (milepost 18.3) to Whipple Ave in Redwood City (milepost 24.8), which enables HSR service to increase from 2 to 4 trains per hour during the peak.  The data tables in Caltrain's study show that this overtake facility provides nearly all the benefits of the "full" mid-line overtake that extends southwards through Redwood City, but presumably at far lower cost.  The transportation-industrial complex's approach to the short mid-line overtake might very well entail demolishing the entire Belmont - San Carlos grade separation and replacing it with a four-track viaduct on concrete stilts.  A more realistic implementation will likely be to tack on another 15 feet of width on each side of the existing grade separations to accommodate new overtake tracks, something that should have been done in 1999 (but why do it right when you can do it twice?).  In San Mateo, new four-track grade separations will be built at 25th, 28th and 31st Avenues.

• Purpose: increases HSR peak capacity from 2 to 4 trains per hour per direction
• Time frame: late 2020's
• Total miles of quadruple track: 14.5
• Grade-separated fraction: 63% (67 of 106 road crossings) 
  
• Trains per peak hour per direction: 10 (6 Caltrain + 4 HSR)
• Cities impacted by construction: San Mateo, Belmont, San Carlos

Phase 4 will be the "full" mid-line overtake, also known as the Great Redwood City Grade Separation, creating a new mid-peninsula HSR stop at Redwood City and grade-separating a dense cluster of six grade crossings.  The four-track mid-line overtake will be extended southwards to milepost 26.3, merging with the existing four-track section.

• Purpose: adds mid-peninsula HSR stop
• Time frame: late 2020's
• Total miles of quadruple track: 16
• Grade-separated fraction: 69% (73 of 106 road crossings) 
  
• Trains per peak hour per direction: 10 (6 Caltrain + 4 HSR)
• Cities impacted by construction: Redwood City 

Beyond that, it gets murkier.  Presumably, the 33 remaining grade crossings that are not removed under Phases 1 - 4 will be addressed on a case-by-case basis, with grade separations designed and built in consultation with the respective cities.  San Francisco's downtown extension to the Transbay Transit Center may finally be built.  Additional passing tracks may be constructed where it's relatively easy and cheap, for example the remaining 2.5 miles from Lawrence to Santa Clara and the "north overtake" in Caltrain's study, an additional 8.2 miles of quadruple track from Brisbane south into Burlingame.

Only one thing is quite certain: the peninsula rail corridor will categorically NOT remain a two-track operation, even if it might still use "primarily" two tracks.  At a minimum, approximately 16 miles or over a third of its length will be quadruple-tracked.  As the process unfolds, it will become apparent that the cities of Belmont, Redwood City, San Carlos, San Mateo and Santa Clara will be the first to suffer the construction impacts.

Belmont Shoots the Moon

The Belmont City Council is crafting a resolution (see original draft, and revised draft to be considered on 9/14) supporting the reinstatement of a cut-and-cover trench option for the high-speed rail authority's San Francisco - San Jose Draft Project EIR.

Underground tracks, favored by the city, were dropped from further consideration when the CHSRA published its Supplemental Alternatives Analysis on August 5th. That action left Belmont (and neighboring San Carlos) with only a single option to be carried forward for further study in the EIR: a tall viaduct. This viaduct is featured in crude renderings and a YouTube video posted by the city.

Belmont is the only member of the Peninsula Cities Consortium that did not have a trench or below-grade option carried forward for detailed study in the EIR, which has city officials fuming.

All Those Grade Crossings In Belmont

The Supplemental AA has caused quite an uproar on the peninsula, especially in the member cities of the PCC, largely because of the vertical alignment options proposed for the four-track corridor. The vertical alignment may need to be changed, requiring either raised or lowered tracks, in order to eliminate about 45 grade crossings along the peninsula corridor that would otherwise have to be closed. These changes are necessary because the California Public Utilities Commission, which regulates grade crossings and pursues a stated policy of reducing the number of such crossings, is exceedingly unlikely to allow four-track grade crossings, much less in a dense suburban environment, regardless of train type or train speed.

One might reasonably assume, then, that the range of vertical options feasible for Belmont would depend solely on the locations and constraints imposed by the grade crossings that currently exist in Belmont. The trouble with this assumption is that the number of grade crossings in Belmont is... Zero.

The existing tracks run through Belmont on a retained fill embankment (shown in photo at left, and known in some quarters as a Berlin Wall) over Harbor Blvd and Ralston Ave. These grade separations were built starting in 1996, opened in October 1999, and did not cut off any pre-existing (legal) access across the tracks. The berm is now perceived as a community division, and prompted the official request to study design options that would enable its removal.

Why a Viaduct?

The Belmont viaduct is an example of the Context Sensitive Solutions process producing an unwanted outcome.

From its very first scoping comments, Belmont expressed misgivings about the berm and requested enhanced connectivity and mobility, in the hope of obtaining a tunnel paid for with OPM (Other People's Money). Taking into account the feedback provided by the Policy and Technical Working Groups at a series of meetings attended by Belmont officials, the Supplemental Analysis Report substituted a tall viaduct for the existing berm because "the Berm option does not enhance connectivity and mobility as well as an aerial viaduct option."

If Belmont disagrees with this outcome, if the city believes the viaduct is not better than a berm, and if this business about connectivity and mobility was all just a colossal misunderstanding, then the berm will simply be expanded to four tracks. The berm is a "fact on the ground" and its visual impact, once all is said, done and litigated, will not be counted against the high-speed rail project. That is the likely outcome if Belmont becomes any more strident in its demands for a tunnel.