The Canyonero of Signals

The San Bruno grade separation, a $155 million project that does nothing for the average Caltrain rider, is nearing completion.  If you wondered where some of that money went, here you go.

The Canyonero of signals is surely this brawny Made in U.S.A. signal gantry mounted on top of the San Bruno grade separation.  The gantry (probably a standard two-track gantry, to save money!) was too wide to be mounted in this location, so two cantilevered concrete platforms, seismically worthy, were built on each side to support the gantry and keep out any terrorists.  [UPDATE: check out the engineering drawing!]  If that wasn't enough, this signal gantry needed its signal house (probably a standard 8'x8' signal house, to save money!) perched on top of the opulent platform as well, with classy electrical conduits slung underneath and a dedicated ADA-compliant staircase allowing maintenance personnel ready access.  Maybe they were trying to save some parking spaces by suspending everything, but the entire area had to be fenced in for security.

East side, showing cantilever platform

West side, with signal house on cantilever platform

Under-hanging conduits connecting the signal heads to the relay shelter

If you asked the engineers who designed this, they could no doubt bend your ear about why it ended up this way and how numerous standards and requirements conspired to force exactly this solution.  That doesn't remove the simple fact that it's wrong.  It isn't simple, elegant, efficient, or thrifty; it fails to satisfy basic ideals that all engineering has aspired to since time immemorial.  The ridiculous, over-wrought outcome of rigid paint-by-numbers adherence to prescriptive requirements and standards would be comical if it weren't such a waste of the scarce taxpayer dollars available for rail projects.  (Or even that sub-category of rail projects solely benefiting automobile traffic flow.)  It's a basic signal gantry, for crying out loud.

Oh, and the new speed limit at the San Bruno curve, the #1 worst curve on the entire peninsula?  65 mph, up from 60 mph before.  It could have been 100 mph if this project had been conceived intelligently.

The concrete has been poured, and this installation shall now and forever stand as a monument to our Transit Industrial Complex, as it embarks on far more challenging endeavors such as electrification, level boarding, the downtown extension, and maybe some day high-speed rail.  The symbolism is hard to avoid.

Focus On: Mission Bay Grade Separations

The San Francisco downtown extension, as environmentally cleared and approved, ends at the existing grade crossing at 7th and Mission Bay Drive (formerly Common Street).  Somebody apparently forgot that this will leave grade crossings at Mission Bay Drive and busy 16th Street, where it still isn't exactly clear how to cross a trolley bus line with a 25 kV electric railroad at grade.  With train traffic expected to double in the next 15 years, conditions at those intersections are expected to become unacceptable, a problem which is now being considered along with redevelopment ideas for the Mission Bay neighborhood.

A number of radical solutions were proposed by outside groups (including the city!) coloring outside the lines of the environmentally cleared and approved DTX project, thus causing significant unease at TJPA headquarters.  To regain control of this issue, the TJPA commissioned a white paper study by engineering consultants Parsons Transportation Group and Jacobs Associates (organizations with considerable tunneling expertise), entitled Proposed Alternative Tunnel Connections to the San Francisco Downtown Rail Extension.

Grade Separation Tunnels Proposed

The billion dollar PowerPoint slide,
from the city's presentation,
used as pretext for dismissing a trench

Curiously, on page 1 of the white paper, the most logical option is summarily dismissed: 

• City SPUR Presentation Option 1 – This option consists of a trench trackway in between the I-280 freeway pilings. The presentation noted that this option may not be feasible, and therefore it is not discussed further in this white paper.
  

This seems like a rather weak rationale for not further discussing or studying a particular option: somebody else, presumably far less-qualified than the Parsons / Jacobs engineering team, happened to cast doubt on it.

One could cast a similarly dismissive eye on the entire study.  It boils down to considering various complex and over-wrought tunneling options (considering arcane subjects such as boring machine types, ventilation zones, and even tsunami run-up) in order to grade-separate these two streets for an estimated cost of well over a billion extra, compared to the current DTX plans.  That's right, BILLION.  Two grade crossings.  If you do the math, at least $500 million a pop works out to about ten times what a typical grade separation should cost.

The study's conclusion, not surprisingly, is to proceed with the TJPA's environmentally cleared and approved DTX plan so as not to upset or delay anything, with the understanding that nothing in the current plan precludes grade-separating in the future, if someone finds more than a billion under a rock.

Grade-separating a couple of streets doesn't need to be so ridiculously expensive or complicated, of course.  It requires an open trench built under the I-280 freeway, along the current alignment of the tracks and between the large pilings that support the freeway.  This trench would pass under Mission Bay Drive and 16th St, then climbing steeply (2.5% grade) to meet the existing portal of Caltrain Tunnel One.  No new tunnels would be built, and the freeway could later be torn down if the city so desires.

This modest 1/2 mile grade-separation trench extension would not require complex phasing; it would be built as part of the DTX tunnel, at an incremental cost far smaller than the proposed grade separation tunnels, with approval of a minor supplemental EIR.  There would be no need for fancy U-walls or tunnel stubs or temporary structures that would have to be modified at some future date with great disruption to train service.  The vertical profile would look very much like this:

Grade separation trench profile view (from west side of tracks)

There are a number of arguments raised against a trench at this location.

Constraint #1: Freeway Pilings

1987 grade separation trench concept

To see what a trench built between the I-280 freeway pilings might look like, we can set our way-back machine to the year 1987 -- more than a quarter century ago -- when Morrison-Knudsen Engineers performed a study entitled Peninsula Commute Service Interim Upgrade Study that included the I-280 diagram at right.  In 1987, the idea of building a rail trench under an elevated freeway wasn't simply dismissed without further consideration.

I-280 straddle bents at 16th Street

And suppose the trench did come too close to some I-280 piles?  The 1989 Loma Prieta earthquake triggered a massive seismic retrofit of the I-280 freeway, during which Caltrans demonstrated a surprising ability to add or move bents under an active freeway.  Even temporary solutions would be acceptable, since the city plans to tear down this section of I-280 in the short to medium term.  The biggest shame would be to spend a billion-plus dollars to avoid freeway pilings that are about to be dismantled.

Constraint #2: Major Sewers

There is already a large sewer passing under the tracks at Division Street (see profile diagram above).  Furthermore, the San Francisco Public Utilities Commission is in the planning stages of a $1 billion sewer project known as the Central Bayside System Improvements, which will involve tunneling a new 27-foot "Channel Tunnel Connection" underneath the tracks (see profile diagram).  The approved DTX project artfully avoids the sewers by surfacing before the sewer crossings, but a trench or tunnel would inevitably conflict with them.  The TJPA study assumes the new sewer tunnel forms the controlling constraint on the vertical alignment of a grade separation rail tunnel, which sends the rail tunnel so deep underground that it can no longer connect to the existing Caltrain Tunnel One.  That's what makes the proposed rail tunnels so long (all the way to Cesar Chavez!) and so expensive.

This raises an interesting question of underground right-of-way: should the rail tunnel yield to the sewer tunnel, or the other way around?  Without very much expertise in the art of pumping enormous flows of sewage, one might guess that sewage is more flexible than trains when it comes to changes in vertical profile.  The SFPUC and TJPA need to be prodded to come to a more realistic agreement on this issue, rather than flushing well over a billion of scarce rail dollars down that new sewer.

Constraint #3: Track Gradient

There isn't a lot of distance between the portal of Tunnel One and the 16th Street crossing.  If 16th Street is left where it is, the tracks need to dive about 28 feet down in that short distance, resulting in a rather steep grade of 2.5%, after accounting for vertical curves.  The TJPA study points out:

• insufficient length is available to transition from the tunnel below 16th Street to at-grade at Tunnel One while complying with vertical grade and curve requirements of DTX, Caltrain design criteria, or accepted railroad engineering practice.
  

Tunnel One North Portal

2.5% is not an impossibly steep grade for EMU electric rolling stock of the sort contemplated by Caltrain and the high-speed rail authority; portions of the high-speed rail system are being engineered with grades approaching 3.5%.  If there is a problem here, it is clearly with overly conservative DTX vertical grade requirements and Caltrain design criteria.  American "accepted railroad engineering practice" is totally irrelevant here, being firmly rooted in freight train operations.

If anybody tells you a 2.5% grade is impossible, ask for a second opinion, preferably from a European engineering consultant.  And there are ways to reduce the required dive: 25 kV overhead electrification clearances could be reduced by several feet by using rigid overhead conductor rails (instead of wires), or 16th Street could be raised by a few feet.  It sure is tight, but it most definitely can be done.

Constraint #4: Keep Caltrain Operating

Shoo-fly concept

Old wye track viewed from
under Mariposa, since removed

Pair of yard tracks to the east of the
main tracks, looking north from 16th

Keeping Caltrain operating during construction of the DTX connection is obviously a major concern.  It would be necessary to construct a temporary shoo-fly track on the east side of the existing tracks, to enable the trench to be constructed where the current tracks exist.  There are already some siding tracks to the east under I-280, but the challenge is to dodge out of the forest of freeway bents at Mariposa Street without violating side clearances between trains and concrete, along the path of an old wye track that was recently removed.  This can most likely be done as shown in the diagram at right; it is a puzzle that requires all the ingenuity our transportation industrial complex can muster.  If bents must be moved, then move them.  If clearances are truly insufficient, CBOSS can be used to enforce single-occupancy of the narrow section.

The TJPA study describes how the DTX project would be staged to allow tying in to a future grade separation tunnel.  The staging concept described would require disconnecting the Transbay Transit Center for several weeks or months while the new connection is made, with the 4th and King terminal used on an interim basis.  This staging concept is surely more time-consuming and disruptive than the trench tie-in work implied in the shoo-fly diagram above, which could probably be pulled off over a three-day holiday weekend.  Far more complex operations were pulled off on that time scale at the Bay Bridge.

Conclusion

Dismissing the trench grade separation alternative is premature and poorly justified.  Boundaries should be pushed and "requirements" should be questioned.  Coordination between the city, the TJPA, Caltrans and the SFPUC should be improved with the help of the Mayor's Office, and if necessary the Governor.  Most importantly, the small sliver of land between Mariposa and Sixteenth should be temporarily preserved from development until the DTX is completed, so that a shoo-fly can be built there.

Without a doubt, this trench would be a tough grade separation to engineer and construct, but when the only alternative is a billion-plus bored tunnel, there are suddenly a billion-plus reasons to take another look to make it work.  With the extensive means of excavation to be mobilized for the DTX project, the incremental cost may be small enough that Mission Bay and Sixteenth can be grade-separated concurrently with the DTX, without delaying the project.

The TJPA and its consultants should be sent back to the drawing board to study the feasibility and cost of the trench option in much greater detail.

Census Driven Service Planning

The diagram at right shows where people live and work along the entire length of the rail corridor from San Francisco to Gilroy, as extracted from government census population and jobs data sets.  The diagram is also available as a PDF.

Implications for Rail Service Patterns

By simple observation of the features of the census population and job distributions along the peninsula corridor, it is possible to infer the desirable features of train service patterns that will maximize commute ridership.

1. Transbay has more than 100,000 jobs within a half-mile radius (more than every other station in the system combined). The concentration of jobs near San Francisco's Transbay Transit Center cannot be understated. This station absolutely must be served by each and every train, and it would be highly counter-productive to terminate any train at 4th and King.
    
2. Silicon Valley shows up in the jobs distribution as a broad hump, mostly homogeneous and stretching from Palo Alto to San Jose.  To serve this rich but diffuse commute market, all trains should make every stop in Santa Clara County.  There should never be any skip-stop service here, and the wider spacing of stops (relative to San Mateo County) will result in only minor trip time penalties.
    
3. San Mateo County has numerous stops, spaced more closely together and with middling jobs and population density.  To enable faster service to and from San Francisco and Silicon Valley, it makes the most sense in this portion of the corridor to operate skip-stop express service alongside local service.
    
4. South San Jose, while south of Silicon Valley, has a massive and untapped residential market that can serve as origin to jobs further north.  Tamien currently functions as a slow and infrequent addendum to the peninsula service, but should be sped up and extended to Blossom Hill.
    
5. Oakdale in San Francisco opens up a new residential market for Caltrain.  The distribution of people nearby is even denser than at 22nd Street.
    
6. The Gilroy extension doesn't make much sense.  There are so few jobs and people here that Caltrain (as primarily a commuter service) should not run to this area.  Serving Morgan Hill and Gilroy is best left for a long-distance operator such as Amtrak California.

Putting all this together, what would a service pattern look like that is tailored to the census distributions, to maximize commuter ridership?  First, it would not look like today's Baby Bullet, which severely under-serves numerous stops.  It would also look very different from Caltrain's latest planning fad, the "peak-period skip-stop zone express," used as the basis for all operational simulations in the blended service analyses published to date.  It would look like this, with distances drawn to scale:

• The Silicon Valley express links the major employment centers of San Francisco and Silicon Valley, highlighted in orange, providing a faster and better alternative to fleets of white luxury buses stuck in traffic on US 101.  It would run every 15 minutes.
   
• The San Mateo local serves all the minor stops throughout San Mateo County, terminating and originating across the platform from the Silicon Valley express at Redwood City.  This provides fast and penalty-free transfers between Silicon Valley and cities all along the peninsula.  The local turns back in Redwood City, minimizing crew and fleet requirements while still providing service every 30 minutes.
   
• Stops in San Francisco and San Jose that have very large residential markets are served in the peak commute direction only.

This service pattern is also well-suited to future blended HSR service: a southbound high-speed train and a closely-following Silicon Valley Express can overtake and catch up (respectively) with a San Mateo local by using a four-track mid-line overtake facility constructed from San Mateo to Redwood City.  Because the local turns back at Redwood City, it does not impede traffic in Santa Clara County.

The time has come to fundamentally rethink peninsula rail service patterns.  Caltrain's "peak-period skip-stop zone express" is almost certainly not the best solution for meeting future demand; a much wider range of options must be considered.

Level Boarding Forum

A few days ago I participated in a panel discussion hosted by Friends of Caltrain on the topic of level boarding and platform compatibility with HSR.  Here are the slides I presented to stimulate the discussion, available either as a 7 MB PDF file or on Scribd:

Level Boarding for Caltrain by clemtillier

It was a good discussion, and I came away with the following impressions.

Things that surprised me in a good way:

• Caltrain is finally considering the possibility of level boarding, although no funding has been identified.
• Bryan Dykes, from the Transbay project, was quite supportive of shared platforms and further pointed out that a bigger constraint on capacity comes from the excessively long platform dwell times requested by Caltrain and HSR.
• The escalator pits on all three platforms of the Transbay Transit Center are built to accommodate any platform height.
• Ben Tripousis of the HSR Authority stated that fare collection and security issues were not necessarily show stoppers for shared platforms, and that platforms could conceivably be shared provided they are built to HSR specifications.

Things that surprised me in a bad way:

• Caltrain has not started the waiver process for CPUC General Order 26-D, although they have acknowledged the potential need to do so.
• Marian Lee of Caltrain stated that Caltrain's reasons for wanting to terminate some trains at 4th and King is to serve certain markets there (presumably in reference to Giants games).  I didn't have a chance to question further, but they seem to be missing that every Transbay train would also stop (underground) at 4th and King-- it's not an either-or, it's one or both.
• Caltrain seems eager to roll out the red carpet for any "tenant railroad" that comes calling.
• The three agencies are clearly not communicating enough about this issue to support the important decisions that Caltrain needs to make very shortly for its new vehicle procurement.

Things that didn't surprise me:

• HSR is going with high platforms, period.  That particular train has already left the station, and there will be no turning back from the joint procurement with Amtrak.  If platforms are to be shared with HSR, they will be high platforms.
• HSR cites as justification for the massive station complex in San Jose that numerous tenant railroads (the "downstairs folks" such as ACE and the Capitol Corridor) plan massive expansion that will need a lot of track and platform space.
• People in the advocacy community are not in agreement on the need for platform sharing.  Some believe that Caltrain needs low (~25") platforms more than it needs platform sharing with HSR at Transbay or anywhere else.

It all came down to this in the end: high platforms, or segregated platforms--pick your poison.  I happen to believe that high platforms will be the lesser of these two evils.  What do you all think?

Beyond Level Boarding

It thankfully happened: after all these years, Caltrain has finally stated something (anything!) about level boarding.  This is an improvement that has long been neglected in favor of the more flashy electrification project.

Around here, level boarding has been discussed several times already, so here are a few oldies but goodies from the archives:

1. Platform height: background and compatibility issues
2. How platform incompatibility results in oversize stations
3. Platform sharing issues between Caltrain and HSR
4. How platform incompatibility is making a mess at SF Transbay
5. Platform height: the full collection of articles from this blog.  Read it and weep.

There is also a nice APTA overview presentation that goes into some detail about the conflicts between level boarding and freight trains.

Caltrain's presentation sums up the main advantage of level boarding in one bullet point, "Operating efficiencies," without clearly stating why it's so important.

• Level boarding reduces trip times.  Without steps, passengers can board and alight far more quickly and the train can save about 15 seconds of dwell time at every station stop.  For an all-stops local, this starts adding up, and saves about half again as much as much time as saved by switching from diesel to electric!
   
• Level boarding reduces delays.  Wheelchairs, bikes, strollers, hordes of drunk Giants fans, airport travelers with suitcases, everybody can get on and off far more quickly and easily.  As any rider will tell you, station dwell times suffer from a statistical "long tail" of agonizingly long station dwells due to a variety of these factors, a sort of station dwell Russian Roulette.  The only way to run this railroad is to add plenty of timetable padding to absorb these anomalies without making a mess of cascading delays.  Fast forward to 2030: under a blended scenario where hourly traffic is doubled on largely the same tracks, this is no longer acceptable.  Station dwell times must be predictable and reliable to avoid making a mess of the morning rush, and level boarding isn't just a nice-to-have; it is a must-have.

Caltrain's tentative plan is to study the possibility of converting all station platforms to 25 inches above rail (up from today's 8 inches) by some unspecified time in the future, and to let high-speed rail have its own set of separate platforms, most likely at 48 inches above rail.

Beyond Level Boarding: Platform Sharing

Level boarding as envisioned by Caltrain is not a trivial undertaking.  It will be expensive, because dozens of platforms will have to be entirely rebuilt.  It will be politically difficult, not in the least because state regulations will need to be overhauled over the strenuous objections of freight railroads.  It will be time consuming, because so many platforms can't be rebuilt overnight.  It will be logistically complicated, because the system will have to continue operating during the transition with a mix of platform heights.

Why not go a tiny bit further to achieve far greater benefits, at far lower cost?

Platform sharing is the next step beyond level boarding, where Caltrain and HSR can share the same platforms at San Francisco, Millbrae and San Jose.  Platform sharing has distinct advantages that have been discussed at length on this blog.  Platform sharing between conventional trains and high-speed trains is already practiced everywhere in the world, except in those countries where track gauge precludes it.

• San Francisco Transbay is where all the action will be.  There are more jobs within a half mile of Transbay than there are within a half mile of each and every Caltrain stop, combined!  Service into and out of this tiny six-track terminal station will be inherently inefficient but crucially important for both Caltrain and HSR.  Platform sharing would increase Transbay capacity for decades into the future.
   
• Millbrae is where the HSR consultants once expressed interest in building a $1.9 billion dollar tunnel to shoehorn new platforms between a handful of residential properties and the existing BART station, which incidentally cost only about $0.1 billion to build.  Never mind the sheer fiscal insanity of it: platform sharing would allow the station to serve both Caltrain and HSR within its existing footprint.
   
• The mid-peninsula HSR stop would be nothing more than another platform where a high-speed train happens to stop, should that be deemed advantageous.
   
• San Jose is where the HSR plans get truly loopy: they want to build a massive station up in the sky over the existing station, hovering on a forest of concrete straddle bents, with a six-mile approach viaduct to the north and an "iconic bridge" (Bay Bridge east span, anyone?) to the south.  Platform sharing would enable both HSR's and Caltrain's needs to be met on a single level, at grade, within the existing footprint of the station.  This would save billions of taxpayer funds that the HSR authority seems to be rather short of.

Why are the respective agencies here not talking about platform sharing?  There is bureaucratic inertia and a general unwillingness to coordinate, sometimes verging on outright hostility.

How To Pull It Off

1. Get HSR to back off from the airport-like notion of separate, dedicated platforms.  Building a TSA security perimeter around the HSR system while leaving Caltrain open won't prevent mass carnage, any more than locking the doors on only one side of your car will prevent theft of your belongings.  HSR can be built far more cheaply with platform sharing.  Of course, none of these measures would be favored by the for-profit Transportation Industrial Complex.
    
2. Get Caltrain to back off from the idea of 25 inch platforms.  Not all bilevel EMUs must have low doors; some of the latest models work with high platforms, and there are smart ways to facilitate a height transition by adding additional doors to the EMU fleet.  Or try another way: get HSR to adopt a 25 inch standard; good luck with that.  And please, don't myopically plan everything around the Bombardier fleet staying until 2030.
    
3. Get the Transbay JPA and San Francisco to understand the economic advantages of platform sharing: a busier, more efficient and more commercially successful terminal, and the opportunity to reclaim much of the under-utilized train parking at 4th and King for redevelopment.

None of these challenges are technical.  They are institutional and political.