13 March 2022

News Roundup, March 2022

It's been a while since the last post, but fear not this blog is still alive.

Caltrain's First Major Accident: on Thursday 10 March 2022, a southbound train was unable to stop before ramming into at least two rail-going flatbed crane trucks being used by an electrification construction crew. 13 people were injured with five requiring hospital treatment; thankfully there was no loss of life. With the new positive train control (PTC) system in place, this collision should never have happened. The fact that it did has drawn scrutiny from the National Transportation Safety Board, which dispatched an investigation team to the site of the accident in San Bruno. The causes of such accidents are often multiple, subtle, and complex, and it will take more than a year to assemble the evidence, identify root causes, and draw out lessons learned. NTSB staff reported some preliminary points at a press conference on March 11th:

  • The impact occurred at approximately 60 mph and the train came to a stop over a distance of over 500 feet.
  • The PTC system is designed to prevent train incursions into established work zones.
  • The PTC system was on and active on the accident train.

While we should be wary of speculation, it is possible to discuss additional relevant points:

  • Train 506 was due to depart Millbrae at 10:34 AM. If as stated the accident occurred just before 10:40 AM, then the train was several minutes behind schedule.
  • The head end of the train stopped at milepost 11.9, so impact occurred at about milepost 11.8.
  • Milepost 11.8 is adjacent to a staging area on the west side of the tracks that is used by the electrification contractor.
  • The location is less than a mile south of San Bruno curve, one of the sharpest curves on the entire peninsula rail corridor. The train would have traversed this curve no faster than the PTC-enforced maximum speed of 65 mph before accelerating again towards 79 mph after the curve.
  • The humped vertical profile of the San Bruno grade separation would have obstructed the train crew's view of the work crew's trucks until about milepost 11.1, at San Bruno Avenue.
  • At an average of 65 mph, the 0.7 miles from the point of initial visibility to the point of impact would have gone by in just under 40 seconds.
  • The 1.25% downhill grade towards the impact point would not have helped the train's emergency braking performance.

Unanswered questions include why were the construction vehicles and the train on the same track, why did the PTC system not prevent the collision, and whether there have ever been other near misses over the past several years of electrification construction. The NTSB report will tell.

May everyone hurt by this accident make a full recovery.

More Electrification Delays: while pole foundations are done, everything else is behind and slipping even from the new delayed schedule. The monthly reports for the project have been significantly abbreviated. The long pole in the tent is the grade crossing warning system, and it just so happens that the new program manager at Caltrain previously managed Denver's electrification project and has direct and personal experience with overcoming the great Denver grade crossing fiasco. From the December report to January, overhead contact system completion has slipped by 4 months. Oddly, after years of study and paying a nine-figure amount to PG&E for substation upgrades, the project is still embroiled in back-and-forth with the utility over how the large single-phase loads of accelerating and braking electric trains might throw the electric grid out of balance. One thing is clear, PG&E knows just how hard to squeeze Caltrain.

Electric Train Modifications: feature by feature, the EMUs are being downgraded to act like an old Bombardier bilevel train. The first EMU trainsets, numbers 3 and 4, are due in California sometime in April March 19th. They will sport two noteworthy changes not seen in any official photos or renderings. The upper set of doors have been sealed off (likely permanently) with window plug panels, and the automatic couplers have been downgraded to old-school AAR knuckle couplers.

Governance Politics: the three-county custody fight over Caltrain rages unabated, sucking all the oxygen away from critical planning for what comes after electrification. Momentum for the business plan effort seems to have stalled entirely. The two key upgrades yet to come are level boarding and a four-track elevated grade separation throughout downtown Redwood City, neither of which are being sufficiently attended to while the board's attention is fixated on questions of power and influence.

CBOSS Dumpster Fire Update: speaking of fires and PTC, the CBOSS case is still making its way through San Mateo County Superior Court (under case file 17CIV00786). Last year, Caltrain and Parsons (the CBOSS prime contractor) agreed to stop fighting each other and ganged up against Alstom (formerly GE Transportation Systems), the supplier of the flawed CBOSS software. Ten years after contract award, six years after breach of contract, and five years after lawsuits started flying, the case is coming close enough to trial that the parties have each prepared a trial brief that very nicely summarizes the making of this fiasco from their respective viewpoints. Here are hot-off-the-press direct links to the Caltrain & Parsons Trial Brief and the Alstom Trail Brief.

Update 3/19 - Board Workshop on Caltrain Finances: the slide deck for the upcoming board workshop to discuss what to do about the railroad's new fiscal reality (high fixed costs and only ~1/3 of the usual farebox revenue) is now posted. What is most remarkable is what is not in the slides, which are basically a giant shrug ¯\_(ツ)_/¯ in the face of the deficit forecasts shown in slide 46. If this is truly an existential fiscal emergency, one wonders why the cost of assistant conductors is not on the budget negotiating table. In 2019, the cost of assistant conductors was $7 million/year, and has since grown proportionally with more train service and annual pay raises, likely to about $8.5 million/year for 2022. With a further service increase to 116 trains/day when electrification begins, the cost of assistant conductors will exceed $10 million/year in 2025. While Caltrain is vulnerable to its labor unions and reluctant to raise such a sensitive matter, the time has come for the second conductor to follow the fate of other redundant and obsolete train crew positions such as fireman and brakeman.

Battery EMUs: from the "are you insane?" department comes a minor bullet point on slide 59 of the same packet, where an area of focus for FY23 is to "Advance sustainability through completion of PCEP and further exploration of potential for battery EMUs." Please don't. The whole point of PCEP and EMUs is to not be seduced by world-unique technical solutions and to not haul around many tons of battery dead weight. The only area that needs focus is to further explore the provenance of this shockingly idiotic idea.

19 September 2021

Down the Tubes with DTX!

DTX overview
San Francisco's Downtown Rail Extension project (DTX), officially known as the Transbay Transit Center Program Phase 2, is a two-mile tunneling project to extend the peninsula rail corridor from its existing terminus in the Mission Bay neighborhood to the purpose-built basement "train box" of the Salesforce Transit Center (SFC). The project is regionally important, as there are more jobs located within a half-mile radius of the SFC than within a half-mile radius of all Caltrain stops combined, from 4th and King all the way to Gilroy. The DTX is nearly shovel-ready, in the sense that environmental clearance is in hand and engineering is being advanced to award construction contracts the moment a key ingredient becomes available: money. Gobs and gobs of money.

Too Big To Fail

The last time the costs of the Phase 2 project were tallied in 2016, the total came to $3.9 billion in year-of-expenditure dollars assuming a 2025 opening. Due to delays, we can anticipate at least another five years of escalation at 5%, bringing us to $5 billion before any changes to the project scope. One can reasonably expect that Bay Area transit agencies' proven inability to deliver mega-projects on budget or on time is quite likely to blow up costs well beyond these figures. As a recent example, the Phase 1 project, completed in 2019, cost $2.4 billion (year-of-expenditure) or about 50% more than the $1.6 billion YOE budget of May 2010, adopted after the train box scope was added.

The DTX project's regional, state and national significance is certainly not lost on our Transportation Industrial Complex. To improve the chances of getting the Phase 2 project federally funded (after which any cost growth becomes easier to fund, following former SF mayor Willie Brown's "theory of holes"), the TJPA is undertaking a phasing study to make the project appear more thrifty. The various approaches include deferring or deleting components of the project, such as a pedestrian connector to BART, an intercity bus facility, and an extension of the basement train box. This nibbling around the edges amounts to $0.4 billion in 2027 dollars or about 8% of the total Phase 2 project cost, a drop in the bucket.

A $30 million project development study is now in the pipeline to get Phase 2 to the state of readiness required to apply for federal New Starts funding by August 2023.

PAX: The World's Most Expensive Grade Separation

If you thought the cost of grade separations is exploding, you really haven't seen anything yet: meet the Pennsylvania Avenue Extension (PAX) addendum to the DTX, a grade separation project that will approach $2 billion for two crossings, reaching the stratospheric cost of $1 billion per crossing.

Even after spending $5 billion (before inevitable cost overruns), the DTX project will leave two existing street crossings at grade, at Mission Bay Drive and 16th Street. Not to be outdone, the city and county of San Francisco has performed a methodical series of planning studies to conclude that a new grade separation project is needed. Rather than taking on the challenge of bending some design rules to keep it simple and make it fit, the favored paint-by-numbers engineering solution is a bored tunnel, which averts any conflict with a planned 27-foot sewer pipe and the sacrosanct pile foundations of the I-280 viaduct, each of which are under the jurisdiction of other agencies. The combined cost of DTX + PAX is estimated at $6.0 billion. Take away the latest (2016) $3.9 billion cost estimate of DTX and you get about $2 billion added for PAX.

Link21 Crashes the Party

Meanwhile, BART is in the early planning stages for beefing up its throughput capacity between the greater East Bay and San Francisco, with a second Transbay Tube. It's worth pausing for a moment to consider what an astonishing piece of infrastructure the first Transbay Tube already is: it carries almost twice as many people during rush hour as the entire ten-lane freeway that is the San Francisco - Oakland Bay Bridge, and at significantly faster speeds. Looking past the pandemic, long-term growth trends indicate that the region must plan for a second Transbay Tube.

Transbay Tube II is the centerpiece of an enormous regional rail program known as Link21, the scale and ambition of which dwarf the DTX. While there are many decisions yet to be made about the implementation details of Link21, perhaps the most critical decision centers on what technology to put in the tube: wide-gauge BART, standard-gauge regional rail, or both.

This question is already of great concern to TJPA, which writes in its August 20, 2021 Phasing Study:

BART and Capitol Corridor’s Link21 program is currently in the early stages of development and has not yet determined a preferred alignment, technology, or rail gauge options to meet their goals and objectives for a future transbay rail crossing. As expected at this stage of development, all options remain available for consideration. For example, Link21 may determine that a second transbay crossing best meets stakeholder needs if it provides additional capacity for the BART network only and does not provide a standard gauge rail crossing of the Bay. BART’s infrastructure and trainset design, however, are incompatible with Caltrain and CHSRA standards. Most significantly, BART operates on a wider track gauge with vehicles that may not meet collision requirements, and therefore a BART-only connection would not relieve congestion and conflicts on the DTX.

We can already see a problematic mindset emerging here, where "BART" is automatically conflated with "five-foot-six track gauge," setting up a false dichotomy of BART-or-standard-gauge.

Caltrain + BART: a Necessary Merger

The false dichotomy of BART-or-standard-gauge threatens to poison the debate around Link21 alternatives. The Transportation Industrial Complex has a vested interest in this incompatibility, as it ultimately forces multiple mega-projects to be built. Why build it right when you can build it twice and get paid twice? From the standpoint of scope and profit maximization, it would then make sense to keep DTX and Link21 as separate projects, despite their overlapping purpose and need to link the greater Bay Area megaregion together using high-capacity passenger rail infrastructure. Seamless integration is good for riders and taxpayers, but not so great for consultants and civil engineering mega-firms. That's why these firms have an interest in propagating the myth that BART and standard gauge rail will always be mutually exclusive.

Removing this false dichotomy is becoming a primary reason for merging Caltrain with BART to form a single Bay Area Rapid Transit system, although there are many other reasons. BART does not have to be synonymous with wide gauge; indeed, BART already operates a seamless standard-gauge extension between Pittsburg and Antioch, and provides day-to-day management of the standard-gauge Capitol Corridor. A new BART peninsula line, while indistinguishable from Caltrain's service vision, would suck the air out of the emerging pointless debate around the track gauge of the second BART transbay crossing. The Measure RR sales tax can serve as a dowry to integrate San Mateo and Santa Clara counties into a restructured BART district.

Link21, to its credit, places equity and inclusion at the forefront of its project development process. The contrast with DTX is jarring, as TJPA's Phase 2 project can easily be viewed as just another gold-plated white-collar rail project enabling nine-to-five technology and finance types to more conveniently access San Francisco's skyscrapers from the affluent suburbs to the south, without ever having to mix with the blue-collar working class. Bringing DTX under the Link21 umbrella, and merging Caltrain into BART, immediately defuses the classism and racism that underlies this anachronistic Mad Men commuter rail vibe.

Transbay Through Running

A stub-end terminal station suffers from fundamental throughput limits related to long turn times and the unavoidable crossing streams of inbound and outbound traffic in the station approach or "throat." For a given number of platform tracks, a through-running station configuration where all trains that come in one end of the station can exit the other end will always provide more throughput capacity, whether measured in trains per hour or passengers per hour. Trains don't have to dwell any longer than necessary at a platform, and don't foul opposing traffic on their way in or out.

With the DTX as it is, past operational analysis indicated that just 12 inbound and outbound trains per hour (8 Caltrain + 4 HSR) would push the limits of the terminus design, with near-saturated platform occupancy. If you uncork the other end of the train box (by having Caltrans clear some right of way i.e. dismantle and redevelop a couple of medium-rise buildings to the East) so that the DTX can connect directly to a new transbay crossing, everything changes. A lot of new capacity is created by virtue of not having to layover or turn trains right smack where your platforms and track real estate is the most expensive.

A recent through running operations analysis commissioned by the TJPA shows that the Salesforce Transit Center could handle up to 20 trains per hour per direction if no more than six of them turn at the station. Any more than six turning movements, and the excessively long platform re-occupancy times (as the study notes, due to the poor layout of the switches leading to tracks 1-4) will reduce throughput capacity to less than 20 trains/hour.

Broken Assumptions at Link21

The TJPA phasing study reports the following direct quote attributed to Link21 project team:

We have received briefings on the operational modeling for DTX and it would seem that even a three-bay DTX tunnel poses operational constraints. A robust service level through the transbay crossing is required to justify investment into Link21. Link21 is envisioning scenarios where not all trains that cross the Bay would continue to San Jose. At this point, there is no other location to turn trains around in the northern peninsula which makes flexibility in DTX important to the Link21 Program.

You read that right: the Link21 team is thinking of turning Capitol Corridor trains at the Salesforce Transit Center, a completely American idea (copied straight from Penn Station New York) that is operationally insane if you think about it for even a minute. In a through-running configuration, all trains that cross the Bay should stop in downtown San Francisco and get out immediately. The California High Speed Rail Authority is planning a huge yard in Brisbane, a perfect place to clean, service and layover Capitol Corridor trains. These deadhead (non-revenue) moves are much less wasteful of infrastructure capacity than treating a through-running station as a terminal.

As was remarked in previous discussions regarding San Jose, the act of parking or laying over trains at a station platform is the railroad equivalent of parking an empty truck in the middle of a bustling loading zone, and then concluding that the loading zone fails to function adequately. Just stop it, don't even think of turning trains here!

The Bottom Line

Here are the pros and cons of merging DTX with Link21:

 Eliminates silly idea of a multi-gauge transbay tube project Could further delay DTX, since Link21 is at an earlier stage of development
 Increases SFC throughput capacity and bang-for-buck, making the enormous cost of DTX worth it
 Exposes DTX to political re-prioritization
 Provides faster Peninsula - East Bay connections than existing BART, and finally "Rings the Bay with BART"
 Greatly reduces scope and profits for Transportation Industrial Complex
 Makes more efficient use of taxpayer dollars by building  one project and building it right
 Requires inter-agency coordination and mergers, which agencies abhor
Provides seamless regional rail connection from SJ and SF to Sacramento, if Capitol Corridor is electrified

Despite the obvious political and organizational obstacles, from the point of view of a rider and taxpayer, the pros vastly outweigh the cons. The answer is then obvious: the DTX should go down the tubes of a new standard gauge Link21 crossing, with Stadler bi-level EMUs operated by BART seamlessly connecting the peninsula corridor (a.k.a. the new BART Purple Line) directly to Oakland and points beyond. DTX should be built without delay and form the first building block of Link21.

05 September 2021

August 2021 Timetable Review

Caltrain was recently returned to more or less full service, with a timetable that is supposedly simpler (with a claim of just five stopping patterns) and features 104 trains per weekday, the most ever. Let's take a closer look using our handy taktulator, which assigns a timetable a score based on frequency and connectivity. The formulation of the service quality metrics underlying the scores is described here.

Caltrain's 2021 peak hour timetable achieves a score of only 96, meaning the service is slightly worse than the taktulator's baseline, the 2011 peak hour timetable, which a decade ago earned our reference score of 100.

Why so mediocre?

It's mostly in the padding. Caltrain service planners have evidently given up on trying to run a tight timetable while also dealing with the debilitating variability in station dwell times inflicted by the lack of level boarding. The right way to solve this problem was and remains to plan for and implement level boarding, a system upgrade that (on a per dollar basis) has even greater service benefits than electrification. The lazy way is what we see here: about 20% of extra padding is baked into the station-to-station run times, allowing a train to easily make up time and arrive "on time" in the event of a dwell time delay along the way. In the absence of a delay, trains can dawdle along even more slowly than the ancient diesel fleet could manage, and just sit at stations until the clock says it's time to go.

Back in 2005, a baby bullet express with five intermediate stops was timetabled at 59 minutes. In 2015, it was up to 61 minutes. Today, the same express runs in 66 minutes. This follows a pattern noted by Alon Levy on the deterioration of speed.

Another factor that explains the lower score is one fewer train per peak hour, resulting in longer intervals between trains. This helps with fleet size, where only 16 train sets (+2 spares) are needed to operate the 2021 timetable where 18 (+2) were needed before. Two more train sets are freed up for maintenance downtime, a vital bit of breathing room as Caltrain's older diesel fleet is breaking down more often. The fleet is well past its expiration date due to the multi-year delays in the electrification project.

Is it optimal?

Can a timetable be devised that uses no more than 16 (+2) train sets and scores better than 96? Why yes it can. Here is a Silicon Valley Express timetable that uses just 14 (+2) train sets with four trains per peak hour per direction, and scores 102.

Why is it better? First, it follows census patterns and puts the stops where they link the most residents and jobs, not where there is the most parking. It is more regular and has fewer gaps with long waits. While this does not figure into the service score, it makes far better utilization of the train fleet (83% of the time in revenue service, versus 70%). More efficient fleet utilization leads to fewer trains and fewer crews being needed to provide the same service, reducing labor and maintenance costs per passenger mile. All this is done without any magic: 15-minute equipment turns, comfy 40-second station dwells and a slightly less absurd padding level of 15%. There are zero overtakes, so fewer opportunities for cascading delays. Finally, this timetable is much simpler to understand for a rider, having just two service patterns.

One can only hope that despite this interim state of mediocrity, Caltrain will successfully implement its "moderate growth" service vision, which scores an impressive 240. Getting there will require reliable 30-second dwells for which level boarding is a must.

Credit to Richard Mlynarik who did the time-consuming part of this analysis.

09 May 2021

The Exploding Cost of Grade Separations

Recently, the San Mateo County Transportation Authority prepared a grade separation program update, discussing past and future projects. What immediately jumps out of this document, and others published by Caltrain, is the exploding cost of grade separation projects. The project budgets are shooting through the roof, vastly outpacing inflation. Typical of this cost explosion is the Broadway grade separation in Burlingame, which will grade-separate a single intersection at the eye-watering cost of $327 million.

Cost Modeling of Historical Grade Separation Projects

With the SMCTA slides giving cost data for past and current projects along the Caltrain corridor, it is fairly straightforward to assemble a simple model of grade separation project component costs. All figures are inflated to 2020 dollars before fitting, and we break out unit quantities for each project of the following project components: fully elevated rail over road crossings, split (partially elevated) rail over road crossings, trenched road under rail crossings, pedestrian tunnels, stations, and the number of miles of corridor where the track elevation was changed. With all those quantities broken out for each project, we can fit a simple model that estimates the unit costs by (empirically, not rigorously) minimizing a least-squares fitting residual. The main result of this model is that projects from the mid-1990s through today consistently cost about $36 million per crossing, with not too much variation:


That brings us back to Broadway in Burlingame, which according to this model should cost only a third of the price tag of $327 million. That's right, even including two pedestrian tunnels and a new station, the entire Broadway project should cost no more than $100 million. This factor-of-three discrepancy raises some serious questions about how this project is being engineered, and whether it should even proceed in its current form. One could counter that the cost model presented here is too simplistic and doesn't reflect the unique local conditions of this project, but the model does okay with predicting the cost of every past grade separation project over the last 30 years. Is this a case of over-fitting the data, or have the engineers behind this project simply lost their senses?

With the most traffic of all grade crossings on the peninsula corridor and train-on-car collisions occurring on average once a year, the Broadway crossing is at the top of the state's priority list for grade separation, and we all know that you can't put a price on safety. That makes the Broadway grade separation project ripe for name-your-price taxpayer extortion.

Insane Costs are Baked in to the Caltrain Business Plan

A Caltrain business plan presentation from 2019 attempted to quantify the expense of partially grade-separating the corridor for each contemplated service scenario. The cost modeling for this was even cruder than the simple spreadsheet model described above: the costs for each project were either copied and pasted directly from each city's estimates (of wildly varying quality), or a standard grade separation unit cost of $255 - $355 million per crossing was adopted. This value is up to TEN TIMES the value estimated from past and present grade separation projects, and flies directly in the face of common sense. Despite the coarseness of this spreadsheet costing exercise, the resulting grade separation costs (on the order of ten billion dollars regardless of service scenario) were passed along into the regional Plan Bay Area 2050 exercise.

Why have costs exploded for a project like Broadway, which has proceeded far enough into detailed design to accurately estimate construction cost?

Cost Drivers

Utility relocation. Whenever you dig, surprises happen where utilities buried underground are found elsewhere than expected. The more and deeper you dig, the more surprises you will find. Every new discovery delays or even stops construction work, running up costs. Almost every digging project undertaken by Caltrain runs into this situation. Just in the last couple of years: in South San Francisco, construction of a grade-separated pedestrian access tunnel was delayed for 17 months, at an additional cost of $10 million (and still counting!) due to utility relocation issues. In San Mateo, the 25th Avenue grade separation project, where several new crossings were dug, was delayed by over 500 days due to negotiations with Union Pacific over the relocation of fiber optic cables. Pacific Gas & Electric also had to be paid to move a high pressure gas line. The budget for utility relocation almost tripled, from $12 million to $32 million, not counting the cost of construction delays. Meanwhile, corridor-wide, Caltrain's electrification program (while not a grade separation) is continually digging up their own brand new train control fiber optic cables, which were buried in places that don't match what the contractor said they did. This is causing many months of delay to foundation installation. The matter is now tied up in court, as one of several smoldering side sagas in the big bonfire of litigation over the CBOSS project, still building up to a climactic jury trial in 2022.

Vertical curves made for freight trains. Changing the vertical profile of the tracks, whether up or down, is subject to design constraints on the radius of vertical curves, or how quickly (and over what distance) the slope of the tracks is allowed to change. You might think this issue primarily affects faster passenger trains, but amazingly, the biggest culprit is heavy freight. Freight cars maintained to the bare-minimum standards practiced in the United States can derail at the slightest provocation, so industry track design standards are set extremely conservatively. The maximum vertical acceleration allowable for freight cars is 0.1 ft/s^2, six times less than for passenger trains. At equivalent speeds, the grade change (for example from level track to a one percent slope) must then take place over a distance six times longer than for passenger trains. If you wanted to design the vertical profile of a grade separation to the most aggressive vertical radii and shortest structure lengths allowable for passenger trains, the freight trains would have to be slowed down to 1/sqrt(6) of the passenger train speed to stay under their six times lower vertical acceleration limit. On the peninsula corridor, where we design for 110 mph passenger trains, short grade separations require that the freight trains can't go any faster than 45 mph. Unfortunately, new grade separations such as Broadway in Burlingame or downtown Redwood City are being engineered for 60 mph freight speed, which makes all the vertical curves (and bridges, embankments, trenches, etc.) almost 80% longer than they need to be for 110 mph passenger trains.

Vertical curves that can't overlap bridge spans. Recent preliminary design drawings, such as for the Redwood City grade separations, reveal a new design constraint has been applied that does not appear in older Caltrain engineering standards. The vertical alignments are configured such that wherever the track crosses over a bridge span (as for a grade separation) there is no vertical curvature. To understand how wasteful and silly this is, ask any engineer--never mind, ask any kid: is a train bridge supposed to look like design A or design B, where this  constraint has been applied so no vertical curvature exists where the tracks pass above the under-crossing? Anyone can see this design rule will blow up structure height, length, cubic yards of concrete, and of course cost. And yet, that's what we see in all the profile drawings.

Paint-by-Numbers Structure Depth. There are well-worn preliminary engineering rules for how thick a bridge deck needs to be relative to the loads it must support and the width of a span. Blind application of these rules during preliminary engineering, when the vertical track profile is often decided, results in bridge decks that are comically deep, as measured from soffit (bottom surface of the bridge) to top-of-rail. These massive bridges result in a much higher track profile, needlessly increasing the length, height, visual impact, and cost of grade separation projects. Bridge structural forms exist that minimize structure depth, and it is often possible to shorten spans by adding support columns.

How to build affordable grade separations

Here are some golden rules for designing affordable grade separations. These are rules that are clearly not being followed for Broadway, or for the Menlo Park plans, or for the downtown Redwood City plans, and directly contribute to stratospheric cost estimates for these projects.

  • dig as little as possible. Wherever possible, go up and over.
  • limit freight train speeds to no more than 45 mph.
  • allow bridge decks and vertical curves to co-mingle.
  • from the very beginning, aggressively minimize structure depths.

Another important consideration, in view of the large number of grade separation projects that will be required to advance the decadal process of grade separating the peninsula rail corridor, is to standardize designs. There ought to be a small set of bridge designs that can be repeatedly adapted to each situation, using standard prefabricated structural elements. Not every project needs to be a special snowflake.

15 December 2020

Redwood City Grade Seps: We Must Do Better

The first preliminary engineering plans for the downtown Redwood City grade separations are out. This isn't your average grade separation: it underpins the most important new piece of rail corridor infrastructure that will enable future Caltrain service to be much better than it is today. Redwood City will become the main overtaking location for Caltrain, with a cross-platform transfer between local and express trains at a new four-track station. We had previously looked at Redwood City issues and laid out the design values that will make Redwood City a high-functioning station.

There are four grade separation alternatives on offer, as described in the overview video:

  1. Fully elevated all the way from Whipple to Highway 84
  2. Partially elevated, in two phases, with Jefferson rebuilt in phase 1
  3. Partially elevated, in two phases, with Jefferson rebuilt in phase 2
  4. Partially elevated at Whipple, with everything else staying at grade

If you're going to be driving a car, the good news is that the designers have done a fantastic job with the car infrastructure, with an A+ on road and intersection design. Unfortunately, this is a grade separation first and a train station second, almost as an afterthought. It should be a train station first. To understand why, let's look 20 years ahead.

Better Service for Many More People

In 2040, which sounds futuristic but is relatively soon, rail service in Redwood City is far better than was ever imagined in the depths of the pandemic of 2020. Here's what is happening:

  • Frequent peninsula rail service. As planned in Caltrain's service vision, electric trains serve a vibrant downtown Redwood City with all day half-hourly service and up to eight trains per hour per direction during the morning and evening peaks, equivalent to adding 5 new lanes to Highway 101. Except it's centrally located, it's quiet, it's emission-free, and it's faster than the hordes of electric autonomous cars gridlocked on 101. At the new elevated four track station, every 15 minutes, in each direction, a local and express train stop side by side on opposite edges of the same station platform. Express passengers who are going to minor destinations transfer to the local, and local passengers going to major destinations transfer to the express.
  • A new station at North Fair Oaks. Following the closure of Atherton station, eliminated for lack of ridership in 2020, a new Fair Oaks station has been created near Fifth Avenue and the southern end of the four-track segment through Redwood Junction. Perfectly spaced halfway between Menlo Park and downtown Redwood City, this station serves neighborhoods that are among of the most densely populated along the entire peninsula rail corridor. The 2010 census showed more than 15,000 jobs and 35,000 historically disfavored residents within a 1-mile radius, and the area has flourished since then with new rail service. Not only is Fair Oaks a significant source of new ridership and revenue for Caltrain, but it is served with zero additional trip time and train operating cost. We will discuss below how this feat of magic is pulled off.
  • New Dumbarton rail service. Inaugurated in the 2030s and using a new Dumbarton rail bridge to the East Bay and beyond, fast half-hourly rail service is relieving regional congestion and making commutes more pleasant and productive. The Dumbarton rail corridor joins the peninsula rail corridor at Redwood Junction, where it merges without interference to peninsula train traffic to create an efficient transfer with Caltrain at the bustling station in downtown Redwood City.
  • Statewide high speed rail service. While Redwood City was not considered a viable station stop in the late 2010s when the statewide rail network was planned, in 2040 it's a no-brainer to connect to it. Redwood City's focus on growth, connectivity and equity has allowed it to outshine more ossified and backward-looking locations like Palo Alto that once embodied the dynamism and innovation of the region. For this purpose, the platforms at downtown Redwood City are 1300 feet (400 meters) long to accommodate double-length high-speed trains.

Focusing on the track layout, the common thread of these four improvements to rail service is the quadruple tracks through downtown Redwood City, connecting the new four track station to the four track segment at Redwood Junction / Highway 84 built at the turn of the century. These quadruple tracks enable parallel train movements into and out of the Redwood City station, making optimal use of the 80-foot width of the rail right of way. This four track layout brings us back to the downtown grade separation project being planned twenty years before, namely now.

The Fatal Flaw

None of the Redwood City grade separation alternatives allow four tracks all the way through downtown. What's worse, the two-track layouts of all four alternatives are wasteful of the scarce and valuable downtown right of way, making no allowance for adding these critically important station approach tracks later. These tracks are required for two very important operational reasons:

  1. Approach tracks allow parallel and independent train movements into and out of Redwood City from the Dumbarton rail corridor without introducing train path dependencies, and thus time keeping vulnerabilities. A train from San Jose should be able to approach the station in parallel with a train from Union City.
  2. Approach tracks allow efficient overtakes, supporting a better implementation of Caltrain's future service vision. Four tracks allow local trains to serve Fair Oaks instead of wasting six to seven minutes at Redwood City waiting for an express to overtake them. A similar operations concept is possible to the north, if San Carlos station is rebuilt with four tracks.
We mentioned earlier that service to Fair Oaks could serve many people and generate new fare revenue in exchange for zero additional crew labor and equipment cost. How is this magic even possible? Let's compare two operating scenarios:

Scenario A. In Caltrain's service vision, express and local trains overtake each other every 15 minutes at the downtown Redwood City station, which will have four platform tracks to allow convenient cross-platform transfers. Unfortunately, with two-track approach bottlenecks from the north and south, trains must enter and leave Redwood City sequentially. That means the local arrives first, waits three minutes for the express to catch up and arrive behind it, then waits another minute for the express dwell time, then waits another couple of minutes for the express to leave and pull far enough ahead. Only after six or seven minutes, even if everything is running perfectly on time, can the local leave Redwood City. Sitting still at a red signal is operational poison, wasting passenger time (all the more so because the perception of delay time is magnified more than 2x by immobility) and driving up crew labor costs ($/passenger-mile). Meanwhile, there is no rail service for Fair Oaks residents, and a long gap in Caltrain coverage between Redwood City and Menlo Park.

Scenario B. The express overtake occurs on a passing section with one or more stations served only by the local. The deceleration time, dwell time, and acceleration time associated with that extra local station stop allow the express to gain on the local while the local is being useful and providing service, instead of just sitting around for an interminable dwell at Redwood City. In the southbound direction, the local arrives in Redwood City, waits three minutes for the express to arrive, exchanges passengers, and leaves the station at the same time as the express. The two trains run side-by-side until the local stops at Fair Oaks. By the time it's ready to go again a couple of minutes later, the express is long gone and no additional waiting is required. The overtake took the same overall time (six or seven minutes) as Scenario A, but used the time productively to provide local service every 15 minutes at a new station serving 35,000 people within a 1-mile radius, at zero additional crew labor or equipment cost.

Here's what the track layouts look like, with station distances roughly to scale, comparing the current condition with Scenario A (planned grade separation configuration) and Scenario B (with Fair Oaks station):

Bonus points are awarded for leaving sufficient room to run a fifth grade-separated track from the southbound tracks to the Dumbarton corridor, flying over Highway 84, as shown in the last panel. This allows seamless merging of the two corridors, without the two streams of rail traffic fouling each other on the way to and from downtown Redwood City. The right time to plan for this is now, not after we pour concrete in the wrong place, even if the funds aren't yet available and there isn't yet a viable Dumbarton project.

Layout of new Fair Oaks station, roughly to scale
Here's what the new Fair Oaks station might look like, near milepost 27. It's about 100 feet wide in an area where the corridor is only 80 feet wide, so it will require taking nine properties along William Avenue. While taking residential properties in a less advantaged neighborhood of unincorporated San Mateo County is never desirable, this must be weighed with the wider benefits to the 35,000 residents of North Fair Oaks and other neighborhoods within a one-mile radius. A narrow slice (~10 feet) of land would be required to be taken from backyards along the opposite side, to make room for the southbound platform. The site has good pedestrian and bus access via Fifth Avenue, and a new pedestrian underpass would connect Berkshire Avenue across the rail corridor, improving neighborhood connectivity. The new Fair Oaks station is very low hanging fruit that can make Caltrain serve more people more efficiently from day one of the new service vision.

The marginal cost of building the grade separations with the additional tracks now is small relative to doing it later, so why would we delay such an important operational improvement or waste money re-doing it twice?

Not allowing for quadruple approach tracks is the fatal flaw of the downtown Redwood City grade separation project. All the alternatives feature two-track bottlenecks that fail to adequately support Caltrain's service vision and impair the future Dumbarton rail corridor service, which is especially concerning because Caltrain and the San Mateo County Transportation Authority seem to have directly participated in the design.

Here are some other comments on the various alternatives:

The Good

  • The roads and intersections and turn lanes and all the car stuff is perfectly designed for smooth and unimpeded car operations.
  • All alternatives feature the four track station, consistent with Caltrain's future service vision, which calls for Redwood City to be the location where express trains overtake local trains.

The Bad

  • All the bridge structures have porky structure depths, ranging up to 9 and even 17 (!!) feet. Every foot that your bridge deck is thicker is a foot that the entire edifice, including all embankments, will be taller. In this case, each extra foot of structure depth is worth about 1,500 18-wheel dump truck loads of dirt to fill the embankment one foot higher! Thicker structures also push roads to be depressed more deeply into the ground, which exponentially increases excavation and utility relocation costs. Thicker bridges at stations needlessly extend stairs and ramps. For the love of Redwood City, use thinner structures! Previous grade separations, such as the one in San Bruno, have used steel beams to keep the structure depth (from soffit to top of rail) to about 5 1/2 feet for an ~85 foot span. Through bridge designs can be even thinner. Grossly excessive concrete bridge structures as seen here are an unmistakable symptom of not caring about costs and impacts.
  • Enormous extra costs are being incurred at the southern end of the grade separation by not allowing the vertical curve at Highway 84 to begin until north of the overpass and the existing turnout, and then limiting the grade to only 1%. This is lazy paint-by-numbers engineering that blindly applies design standards without regard to their consequences, which in this case push Chestnut Street and others much deeper underground than is necessary. If there ever was a case where an exception to Caltrain design standards was warranted, this is it. Using a 2% grade and starting the vertical curve south of Highway 84, squeezing every inch of available vertical clearance under Highway 84, will save millions. In a modified Alternative 1, Main and Maple may not even need to be sunk at all.
  • The platforms are 900 feet long, and there may not be sufficient clearance left between the station tracks to extend them to 1300 feet (400 meters) later to support high-speed rail service at Redwood City. While this is not in current official plans, it makes sense and it would be a shame to preclude it. There is plenty of room in the site to allow it.
  • The station should be open underneath, not built on a filled embankment. It should allow a future Broadway light rail line to shoot straight through, right under the Caltrain platforms. As proposed, all the alternatives torpedo the city's Broadway street car project.

The Weird

  • The vertical profiles have unusual constraints on vertical curves, seemingly not allowed over or under bridges. That is just silly and grows the embankments unnecessarily taller.

  • Hopkins Avenue should be re-connected across the tracks. It's basically a freebie to improve neighborhood connectivity.
  • All alternatives, not just 2 and 3, should start near Howard Avenue in San Carlos, extending a four track station approach as far north of Whipple as possible. In the future, if the San Carlos station is rebuilt as a four track overtaking station, dwell times at Redwood City can be further shortened than is possible with just the Fair Oaks station, using the same overtaking principle.

  • Pennsylvania Avenue is treated as a city street, not the encroachment on critically important railroad right of way that it actually is. It will be needed anyway for temporary shoofly tracks during construction. The grade separation project should not give away valuable railroad right of way to automobile uses.
  • Alternative 4, at grade, has no clear way to access the station platforms and forms an even more formidable barrier through downtown, seemingly in contradiction with project goals.
The Redwood City grade separation is about much more than just grade separating roads to make traffic flow freely. Like any project on the rail corridor, it needs to be planned and built not only such that future improvements to rail service aren't made more difficult or impractical, but to start putting in the hooks for those improvements now. The marginal costs aren't zero, but they're so much less than fixing it later. Caltrain has a deplorable track record with future-proofing grade separation designs: the San Bruno grade separation and station, just recently completed in 2014, is already officially planned to be partially demolished for the high-speed rail project to straighten out a curve that could have been built correctly in the original design (reference HSR San Francisco - San Jose project DEIR Volume 3, Alternative A, Book A1 plan and profile drawings, sheet 7).
The same kinds of silly mistakes are now starting to be made in Redwood City, with an efficient layout to facilitate express overtakes and Dumbarton service being fumbled by oblivious consultants who excel at the road details and don't seem to appreciate the rail details. When they've got a hammer, the whole world looks like a thumb.