Build a Dumbarton Rail Tunnel

The Dumbarton water tunnel TBM,
being assembled for the start of its
five-mile drive under the Bay in 2011.

Boring a new tunnel under the Dumbarton corridor, through muddy soils right under a sensitive national wildlife refuge, seems like an impossibly difficult, risky and expensive undertaking in this day and age. But here's a little-known fact: it's already been done.

From 2011 to 2013, a 15-foot diameter tunnel boring machine (TBM) quietly bored a new five-mile tunnel under the Bay from Menlo Park to Newark. The $288 million project, the first tunnel ever bored under San Francisco Bay, is part of the Hetch Hetchy Water System and was built to contain a 9-foot diameter drinking water supply pipe that feeds San Francisco and the peninsula. The TBM that bored the tunnel was an EPB (Earth Pressure Balance) machine and advanced so quickly that it had to wait underground at the far end of its drive, while an access shaft was prepared so the machinery could be retrieved. There were few geotechnical surprises along the way, of the sort that can sometimes blow out tunneling budgets and schedules. The geological layers of clay, gravel and rock under the Bay along the Dumbarton corridor are now better known than they have ever been, and any "geotechnical risk" is effectively retired after the actual boring of an actual tunnel.

Of course, a rail tunnel would be larger and cost far more than the $288 million water tunnel. To safely carry train traffic at speeds of 125 to 150 mph, two parallel tunnel bores about 30 feet (10 meters) in diameter would be needed, connected by cross-passages about every 1000 feet and with a handful of ventilation and emergency evacuation shafts to the surface.

How Much Would a Dumbarton Rail Tunnel Cost?

The costing of bored rail tunnels is reasonably predictable, with models having been developed for example by the High Speed 2 project in the United Kingdom. The HS2 tunnel cost model can be applied to estimate the known cost of the Dumbarton water tunnel, as a sanity check. The model uses 2011 British pounds, which we convert to dollars using the exchange rate of $1.57 in 2011. The length of the water tunnel is about 8000 m, and it took about 100 weeks to drive and clear out (100 m/week drive and 400 m/week clear-out). Tunnel construction cost is scaled by bore diameter as indicated by section 4.2 chart G.1; the single-bore water tunnel has 23% of the perimeter of a twin-bore 9.6 m tunnel considered in the HS2 document. Disposal cost is scaled by bore area; the single-bore water tunnel has 11% of the area of a twin-bore 9.6 m tunnel. Note the water tunnel does not require portal or ventilation / evacuation facilities.

Item	Description	Quantity	Unit	Rate	Cost ($M)
Purchase of TBM	EPB Boring Machine	1	ea.	$28M	28
Support Costs	Fixed Costs (EPB Machine)	1	ea.	$55M	55
	Time-related costs	100	weeks	$1.7M/week	170
Tunnel Construction	EPB Tunnel (single bore)	8000	m	$8000/m	64
Disposal of Material	Off-site disposal	8000	m	$800/m	6.4
TOTAL					323

The HS2 model seems to predict the direct construction cost of the existing Dumbarton water tunnel reasonably accurately, landing within ~12% of its actual cost. Most of that difference can be ascribed to the much smaller boring machine, which the HS2 model cannot account for; the Dumbarton TBM cost about $10M.

Scaling It up for Trains

The unit costs from the HS2 model can be used directly to scale up to a Dumbarton twin-bore tunnel ready for high-speed electric trains. This tunnel will be a bit longer than the water tunnel, since unlike water, trains can't just climb vertically into and out of the tunnel. Assuming 2025 dollars, which are worth about 20% less due to inflation, you get the following direct construction costs:

Item	Description	Quantity	Unit	Rate	Cost ($M)
Purchase of TBM	EPB Boring Machine	2	ea.	$35M	70
Support Costs	Fixed Costs (EPB Machine)	1	ea.	$69M	69
	Time-related costs	120	weeks	$2.1M/week	252
Tunnel Construction	EPB Tunnel (twin bore)	10000	m	$43000/m	430
Disposal of Material	Off-site disposal	10000	m	$9000/m	90
Tunnel Portals		2	ea.	$39M	78
Tunnel Shafts	Ventilation / Emergency	3	ea.	$39M	117
Systems	Electrical / Mechanical	10000	m	$8000/m	80
TOTAL					1186

The basic construction bill comes to $1.2 billion in year-of-expenditure dollars for a state-of-the-art twin-bore electric rail tunnel built in the middle of the next decade. This figure is then burdened roughly as follows:

• 3% environmental mitigation
• 25% contingency
• 6% engineering design
• 3% program management
• 4% construction management + 0.5% agency fee + 4% mobilization costs

These overhead rates compound with each other, combining to 53%. The expected all-up cost of a twin-bore Dumbarton tunnel is then about $1.8 billion.  Add to that the expense of removing the old bridge, estimated by Samtrans at $150M, and we reach almost $2 billion.

Why Tunnel?

As we are often reminded on the peninsula, a tunnel puts the trains out of sight and out of mind. In this case, it actually makes sense to build one because it crosses a terrain obstacle, San Francisco Bay. A new tunnel avoids visual and noise impacts, removes the blight of the old bridge, enables higher train speeds without endangering wildlife, and can be made more resilient to sea level rise than a new bridge. A new tunnel is not much more expensive than the options now being contemplated as part of the Samtrans Dumbarton Transportation Corridor Study, where it was summarily and improperly dismissed as too expensive, risky, burdensome and impactful (see Table 6-4). The tunnel option deserves a second and more serious look.

A Dumbarton tunnel could extend under University Ave and Willow Road in Menlo Park, grade separating both for a marginal cost that our model places at $132k per meter of twin tunnel (in 2025 dollars). The Samtrans study estimates each grade separation to cost about $200M (in 2017 dollars), so the two grade separations are worth about a mile of extra twin tunnel if you've already got TBMs in the ground. That's before the grade separations have to be rebuilt to accommodate sea level rise.

A Dumbarton tunnel would provide more cost certainty than a bridge. The last bridge the region built overran its cost estimates by several hundred percent, while the Dumbarton water tunnel was on time and on budget. Tunnel boring is a well-developed technology that is highly automated and doesn't use a lot of expensive construction labor. Some people are working on making it even more automated.

San Francisco to Tracy in 35 minutes

A Dumbarton tunnel could serve as a key component of a new regional rail link between the Bay Area and the Central Valley, putting San Jose much closer to Sacramento, and San Francisco under an hour from Stockton. It could eventually serve as the entry point of high-speed rail into the Bay Area, making faster trips from anywhere in the Bay Area to Sacramento and southern California. The performance simulation at right shows a high speed train passing through Tracy just 35 minutes after departing San Francisco Transbay, traveling along the Altamont SETEC alignment. This would vastly simplify the "blending" of Caltrain and high-speed rail since the latter would enter the peninsula rail corridor at its midpoint, sharing slow tracks for only half the distance of the existing plans and requiring fewer overtake maneuvers.

A new Altamont / Dumbarton high speed regional rail link could replace and combine the fragmented hodge-podge of projects and agencies variously pushing Altamont Commuter Express extensions, Valley Link, Livermore BART, a second BART Transbay Tube, the high-speed rail system, and whatever Cross Bay Transit Partners might come up with for Dumbarton, each of which nibble at different edges of the same basic problem: our regional mobility is inadequate and relentless traffic jams are crushing the souls of hundreds of thousands of people in the I-580, I-680, I-880, US-101 and CA-92 corridors.

The Dumbarton rail corridor needs to be thought of as so much more than a simple bay crossing that relieves traffic for people who work at Facebook. This is a one hundred year piece of infrastructure that can unclog an entire region, and it needs to be engineered for it. A tunnel for $2 billion (in 2025 dollars) is a sound and future-proof investment.

Will BART Bust a Move?

The unfortunate reality of Bay Area transit politics is that twenty-eight agencies compete for funding and ridership with very limited coordination.   At the top of this pile is BART, the biggest of them all.  Not so much BART the transit operator, but BART the expansion-thirsty transit-industrial complex (functioning somewhat like the military-industrial complex), as facilitated by the Metropolitan Transportation Commission (MTC).  (photo at right by cplbasilisk, modified with permission)

With recent developments in the peninsula high-speed rail story, it's worth taking a step back and imagining BART / MTC's next moves in this slow-motion game of political chess, assuming for a moment the following motivations:

• Expand as much as possible, constructing the most new infrastructure in the most corridors using the most consultant engineering and "craft hours" of construction labor
• Soak up as much federal, state and local funding as possible
• Take over high-ridership corridors, even at the expense of other agencies
• Ring the San Francisco Bay with BART, as initially planned in the 1950s

The resulting exercise can either be viewed as a crackpot conspiracy theory, or as a simple thought experiment rooted in recent history.  Where MTC and BART have successfully assembled billions of dollars for the Millbrae/SFO and San Jose/Santa Clara extensions, Caltrain has repeatedly floundered: no downtown extension, no electrification, no Dumbarton rail, and the list goes on and on...  Supposing this historical pattern were to be sustained, what specifically would be BART's logical next moves?

Move #1: Drop Support For Pacheco HSR.

The long-running Pacheco-Altamont controversy over the Bay Area HSR alignment, still simmering in the courts, is driven on one hand by not-in-my-backyard sentiment in communities impacted by the Pacheco alignment (notably Palo Alto, Menlo Park, and Atherton) and on the other hand by transit activists who argue that the Altamont alignment makes far more technical sense to serve the immediate transportation needs of the Bay Area in a coordinated and sustainable way.

BART and MTC were firmly in the Pacheco camp because of the need to preserve for BART a key piece of rail right of way between Fremont and San Jose (the former Western Pacific line, purchased by VTA in 2002).  This right of way would almost certainly have been claimed by HSR under any reasonable Altamont scenario.  Worse, a blended HSR/commuter rail project could have undermined the very purpose and need for BART in that corridor.

Today, this concern has been overcome by events, and the BART extension to San Jose is a done deal.  Pacheco HSR no longer plays a role in defending this important BART turf, and thus may no longer garner the same level of support from BART and MTC as it once did.



Move #2: Promote Altamont HSR with a BART Connection at Livermore.

The BART board recently approved a more detailed study of a future extension to Livermore, along I-580.  While this extension is a waste of money on its own merits (as are most BART extensions), and is still far from becoming reality, it could be sold as a key enabler for a phased implementation of HSR, especially under a budget-constrained environment.

Livermore as a BART-HSR transfer point has been considered before, if only discreetly, as part of the half-hearted "Altamont overlay" that the CHSRA has been studying in addition to the baseline Pacheco Pass alignment--always with the insistent disclaimer that the Altamont corridor serves a completely different "purpose and need" than the high-speed rail project.  Meanwhile, MTC suggested as recently as 2007 that HSR terminate at Livermore BART, absorbing all HSR ridership into BART (see comment L017-8).

As an interim phasing opportunity, Livermore BART would actually work quite well:

• Earlier and quicker HSR service to downtown San Francisco and the greater Bay Area
• Earlier and quicker HSR service to Sacramento (quicker than the Amtrak Capitols)
• Cheaper construction with less tunneling to achieve "Bay-to-Basin" connectivity

The Livermore BART extension would be routed south along Vasco Rd. or Greenville Rd., past the Laboratory, to terminate just south of Livermore at a new BART/HSR interchange station on the outskirts of town.  This station would be located on an Altamont HSR alignment proposed by outside groups but studiously ignored by the CHSRA.  This Altamont HSR route is known as the SETEC alignment, after the French HSR consulting firm that performed the preliminary engineering.  The SETEC alignment is noteworthy in that it avoids major residential property impacts to Livermore and Pleasanton, one of the main arguments used by the CHSRA to select Pacheco in the environmental study process.

Here is a rough point-by-point comparison of Altamont/Livermore and Pacheco/Gilroy interim scenarios:

	Altamont HSR to Livermore	Pacheco HSR to Gilroy
HSR Trip Time, from Fresno	0:48 Fresno - Livermore	0:39 Fresno - Gilroy
Continuing Trip to San Francisco	0:57 on BART Livermore to Embarcadero	1:45 on Caltrain Gilroy to SF (electrified)
Fresno - San Francisco CBD	~ 2:00 (40 minutes quicker) including transfers	~ 2:40 including transfers
Fresno - Oakland	~ 1:50 (50 minutes quicker)	~ 2:40
Fresno - San Jose	~ 1:50 (10 minutes slower) assumes BART to SJ	~ 1:40
HSR Track Length	140 miles (25 miles more)	115 miles
Phase 2 HSR to Reach Sacramento	60 miles (50 miles less)	110 miles
HSR Tunnel Length (interim)	about 4 miles (6 miles less)	about 10 miles

Using the money saved by tunneling only 4 miles to Livermore instead of 10 miles to Gilroy, the additional 25 miles of track to reach Livermore are easily paid for-- and then some, since 50 miles of track will already have been built to reach Sacramento, as opposed to zero for Pacheco.

Move #3: Dangle the Carrot of a PAMPA Subway.

The Palo Alto Weekly recently published an article headlined "Four-track design back on the table for high-speed rail," apparently implying that it was once off the table.  That seems to be the crux of a major disconnect between the city and the high-speed rail Authority.  The blended Caltrain / HSR plan, as proposed in recent months by Simitian-Eshoo-Gordon and currently being analyzed by Caltrain, was always viewed by the CHSRA as an intermediate phase, a stepping stone to the immutable objective of a four-track high-speed railroad through PAMPA (Palo Alto - Menlo Park - Atherton).  This viewpoint is borne out in the 2012 draft business plan.  Palo Alto, on the other hand, views the blended plan as a final state of the peninsula rail corridor for the foreseeable future, and believes that the four-track plan should no longer even appear in the program EIR.

BART's best move here is again to promote Altamont HSR.  For PAMPA, the advantages are thus:

• No four-track HSR grade separations, ever
• No additional right of way (a.k.a. eminent domain) needed, ever
• No HSR traffic on top of commuter rail traffic (only 6 trains per hour per direction)
• Future opportunity for a two-track BART subway, considerably cheaper to construct than a four-track high-speed corridor.  A two-track BART tunnel box is four to five times smaller, in cross-sectional area, than a four-track HSR tunnel box.  This makes it remotely feasible to have the cities participate in the financing of a subway, much as was done in Berkeley in the 1960s, to further enhance property values.

For BART itself, the main advantage of Altamont is of course to preserve the future possibility of ringing the bay by connecting Santa Clara BART to Millbrae BART.  The argument that BART can make in pleading this case is that all existing infrastructure north of Millbrae (i.e. fresh grade separations in San Bruno, and existing tunnels to San Francisco) would be dedicated exclusively to HSR, thus mitigating the astronomical cost of accommodating Caltrain detailed in the 2012 business plan.

As billions of dollars slowly coalesce for a possible blended HSR / Caltrain plan on the peninsula, time will become pressing for BART to bust a move.  If the motives that underlie the above narrative are remotely true, then any attempt to electrify the peninsula corridor shall be thwarted, just the same as it has been in past decades.

Holiday Required Reading

HSR Done Right

Sometimes, it's useful to look beyond the peninsula for context on what works best locally.  Here's a graphic from Richard Tolmach (in the latest TRAC Newsletter) that pretty much says everything that needs to be said about the California High Speed Rail Project.

As can be observed, the route that Tolmach and other organizations (including the plaintiffs in the Atherton lawsuits) have been advocating for years is very different from the route that the CHSRA is stubbornly advancing through the environmental clearance process.  In the Bay Area, the notable departure from the official plan is that HSR would branch off from the peninsula rail corridor at Redwood City, head over a new Dumbarton crossing, and zoom across Altamont Pass along the SETEC Alignment.

What does this have to do with anything peninsular?  Plenty, as it turns out.  Read on.

Caltrain's Blended Analysis

Caltrain recently published its analysis of the "blended" proposal, where Caltrain and HSR would share the peninsula rail corridor using less ambitious and expansive infrastructure than the four-track viaducts originally envisioned by the CHSRA.  This analysis concludes that it's feasible to run mixed Caltrain / HSR operations, although Caltrain service would be bunched up (with irregular skip-stop service patterns limited to six trains per hour) and HSR would need to slow down (about 40 minutes, rather than the planned 30 for SJ-SF) and be limited to 4 trains per hour.  On page 46, the document mentions that

The increased two-track shared use corridor distance from Whipple Avenue to San Jose Diridon, makes it very difficult for a 110 mph train to leave San Jose without encountering delay prior to reaching the overtake, and for a southbound HSR train to keep from being delayed by the Caltrain train it follows after the overtake.

Translation: sharing tracks should be done for the bare minimum distance, and certainly not 50 miles from SF to SJ.  Branching HSR off the corridor in Redwood City is a scenario that was NOT analyzed because it runs against Pacheco orthodoxy.  There is little doubt that it would make for an operationally superior solution (as computed by our free service pattern generator) with more Caltrain service, more Caltrain expresses, better transfer opportunities, easy-to-memorize clockface service patterns, and 125 mph HSR speeds... better in every way than the best scenarios LTK could come up with given the flawed assumptions of the study.

Speaking of better service planning...

The Swiss Take On California

Switzerland arguably has the most advanced, integrated and optimized rail service planning in the world.  The Swiss rail operations consultancy SMA+Partners supported a doctoral thesis analyzing the California rail network (including HSR) from an operations perspective.

Ulrich Leister's thesis (see executive summary) "applies a lean and rational approach to planning that is network and schedule-based.  A precise computer model is used to test different ideas such as infrastructure layouts or train types.  Gradually, the schedule is refined and optimized until the required rolling stock and the minimal amount of infrastructure needed to operate all the scheduled trains is determined."

This operations-first approach will likely come as a breath of fresh air to readers bewildered by our local experts' cost-maximizing ways.  A full copy of the thesis will be linked here as soon as it is made available.  Note in the network diagram at left that the Altamont route is identified as operationally superior, which will come as a surprise to CHSRA consultants who stubbornly insist Pacheco is the only way to go.

The Japanese Take On California

About a year ago, the East Japan Railway Company gave the CHSRA a peer review of their operations and maintenance approach.   Section 2.1.2.6 of this document addresses mixed service with other rail carriers.  It is reproduced in full below, with links added to relevant articles that echo the exact same points on this blog.

Based on JR East's experience of operating conventional train and Shinkansen train on the same track, following three aspects should be carefully considered.

First, the timetable should be carefully planned. The shared operation segment is likely to be the bottleneck of the high speed train timetable since delay in the conventional line will affect the entire high speed trains network. Therefore, if transport capacity is required, 'parallel' timetable (that is, High Speed Train and conventional train operate at the same speed) or increase the capacity of the commuter trains and reduce the frequency will be the solution. To establish a more flexible timetable, additional facilities will be required both in high speed train and the conventional lines. For example, siding tracks are required in stations in this segment, commuter train vehicles with good acceleration should be implemented, speed restrictions on curves should be reduced, more signals should be allocated, etc.

Second, rolling stock should be taken account. If the High Speed Train vehicle width is different from that of conventional trains, platforms must be trimmed, and/or boarding steps must be installed either on the high speed train or on the commuter train. These boarding steps may exceed the loading gauge at some areas, so they should be stowed away while the train is running. The difference in height of the doors of the rolling stock should also be taken into consideration. Finally, compatibility of Automatic Train Control system for high speed train and conventional train should be considered. Since the safety equipment is indispensable for either train, multiple safety equipments must be installed on the rolling stock, and radio communication system must also be shared. These must be switched at the border station. Preventing malfunction both on the wayside and on-board is also important.

All this good advice has clearly fallen on deaf ears.  For example, platform interface coordination is not even remotely on Caltrain's radar, and the HSR project is actively working against it.