31 July 2016

Future Proofing Hillsdale

The next big grade separation project on the peninsula rail corridor will be at 25th Ave in San Mateo, a logical next step in the decades-long process to grade separate the corridor.  This grade separation will establish a 6.5-mile stretch of 100% grade separated right of way, laying the groundwork for a future four-track mid-line overtake facility that will allow express trains to overtake slower commuter trains under the "blended system" jointly planned by Caltrain and the HSR authority.

Preliminary rendering of new
Hillsdale station with island platform
The latest plans presented to the Caltrain board of directors show a split-grade elevated solution, built sufficiently wide for four tracks but initially only fitted with two tracks spaced on approximately 48-foot centers.  The Hillsdale station is moved north by a quarter mile to straddle 28th Ave, and fitted with a central island platform sized approximately 36 x 700 feet and built 8 inches above the rails.

Vertical circulation to this island platform is provided at the north end (two stairways connecting to the sidewalks on each side of the new 28th Ave underpass) and the south end of the station (a new pedestrian tunnel with one stairway and one wheelchair ramp).  In cross section, the new Hillsdale might look like this:

Of course, the accelerated schedule for its completion is closely linked to electrification, so quite soon thereafter it might look like this, with mixed diesel and EMU service.  Note that per Caltrain plans, the overhead contact system is 22 feet above the rails. plenty to clear even the tallest freight cars.
It's not too difficult to guess what happens when the blended system overtake tracks are built: the new platform and all associated vertical circulation (stairs and ramp) will be demolished, to be replaced by a pair of new express tracks right down the middle of the corridor.  A first phase of this "New New Hillsdale" station would like this, hopefully with level boarding platforms.  Note the new portal configuration of the overhead electrification, to span across four tracks and two platforms without placing poles close to the edge of the new platforms:
After demolition of the "New Hillsdale" island platform, the original 48-foot track centers allow for two additional overtake tracks and a central fence (track spacing 15 + 18 + 15 feet) to prevent passengers from crossing between the two new side platforms of the "New New Hillsdale."  Including stairs, the "New New" station is 106 feet wide and looks as much as possible like any station on Amtrak's Northeast Corridor.  It could almost be mistaken for Princeton Junction:
While it's a fine idea to build the new grade separation sufficiently wide for four tracks, demolishing the "New Hillsdale" station only to replace it so soon with a "New New Hillsdale" seems terribly wasteful. Perhaps this is another case of "why build it right when you can build it twice?" Surely there is a better way.

Rebuilding Hillsdale Once and for All

There's a much better way to build the New Hillsdale once and for all.  It initially looks like this:
Note the central island platform is a full-height level boarding platform, disguised for now as an 8-inch platform by raising the track bed by 51 - 8 = 43 inches using a thicker-than-usual layer of ballast. The final footprint of this station, which will ultimately have the HSR overtake tracks on the outside, is less than 100 feet wide at the platform. The footprint will never change; all the concrete has been poured and not another cubic yard is needed in the future. Soon after electrification, mixed EMU and diesel service would look like this:
The overhead contact system is built in its final configuration 22 feet above the eventual height of the tracks; because the tracks are raised by 43 inches, the vertical clearance is temporarily reduced to 18' 5" which still safely accommodates Plate F freight cars, the tallest that have historically been used in this part of the corridor.  Therefore, there is no constraint to freight service.  This electrification will never change, with all the portals in their final configuration.

When all the diesels are gone and it's time to transition to level boarding, a track maintenance project takes place over a weekend.  43 inches of ballast are removed from under the tracks, using standard track maintenance machines.  The rails are never even disconnected.  (Not to be too flippant, this is still a major track maintenance operation that would require sophisticated planning and modern high-capacity machinery; but it is certainly within the realm of what Caltrain has done before.) Minor lateral adjustments are made to track and overhead contact system alignment, yielding this for the Monday morning rush:
Not a single cubic yard of concrete is required either to convert to level boarding, or to add the overtake tracks once HSR service begins on the peninsula.  The final blended system configuration is ultimately this:
Built once, and built right!

That FSSF Thing

Placing the express overtake tracks on the outside, in a fast-slow-slow-fast or FSSF configuration, as opposed to the traditional slow-fast-fast-slow or SFFS configuration inspired by road design, is a key architectural decision for the blended system.  The forces of traditionalism will argue strongly for SFFS because that's how it's "always" done, yielding nice straight express tracks down the middle of the corridor-- but clear exceptions to this "rule" exist, with examples of FSSF corridors in these videos from Sweden (with 125 mph express trains!) and Australia.

The fatal operational flaw of traditional SFFS corridors is that when a track must be taken out of service, either accidentally or intentionally for maintenance, commuter trains either must cut across the express tracks (fouling express traffic) to reach the opposite platform, or use super awkward bridge plates to board from the fouled express track.  In contrast, an FSSF island platform is operationally flexible: the train simply crosses over to the opposite side of the island, without ever getting in the way of express traffic.  For the peninsula "blended system" where Caltrain and HSR share the corridor, the operational headaches of SFFS could prove unworkable in the long run as the rail corridor is maintained.

One argument systematically trotted out against FSSF is this: wowing express trains around the outside of every island platform will make for a slalom "barf ride" that will give HSR passengers motion sickness, if not downright whiplash.  This argument intuitively rings true, but turns out to be patently false when you run the numbers.  In reality, an express train blasting around the Hillsdale island platform at 125 mph will do so on curves with a radius greater than four miles, requiring just 2 inches of superelevation to be rendered imperceptible to passengers.

Download FSSF island platform plans
for every station on the Caltrain corridor
(3.3 MB PDF, see page 9 for Hillsdale)
Another argument leveled against FSSF is that the island platform arrangement requires additional right of way compared to a traditional SFFS outside platform arrangement.  The footprint of a FSSF station can be made nearly as compact as a SFFS station, especially if the central island platform (shown in the above diagrams at 33 feet wide) is slightly tapered at its ends, yielding an imperceptibly curved platform that is for all practical engineering purposes the same thing as a tangent (straight) platform. In any case, the available right of way at the Hillsdale location is a generous 150 feet wide, making such footprint considerations moot.

The Takeaways
  • DON'T rebuilt infrastructure multiple times.
  • DO build it once and build it right, in its final configuration
  • DON'T build station platforms that are not compatible with level boarding, where this can be avoided.
  • DO create the Caltrain engineering standards for level boarding.
  • DO build the new Hillsdale station with a level boarding platform, years before the transition to level boarding occurs, by temporarily raising the track bed to make the platform only 8" tall.
  • DO build the new Hillsdale station as an island platform, even after high-speed overtake tracks are added
  • DO put the high speed tracks on the outside, in the FSSF configuration, for operational flexibility.

25 July 2016

Steaming Pile of CBOSS

CBOSS, the Communications Based Overlay Signal System, is a Positive Train Control (PTC) system being developed by Caltrain to prevent human error from killing or maiming passengers or rail workers.  It is a deeply troubled project.  Caltrain recently requested a peer review of the project from APTA, the American Public Transportation Association, whose subject matter experts were given access to personnel and documents.

Download the final report from the peer review here (500 kB PDF).

It's fair to say our worst fears have come true:
  • the project manager does not have the requisite technical experience
  • there is no project schedule, and October 2016 is just another month on the calendar
  • inter-operability requirements and test methods are not defined or agreed upon
  • configuration management is not just out of control, but completely lacking as a process
  • software and network security is an afterthought
  • animosities between project management and the contractor are impeding the resolution of technical issues
  • operator training has not started, and the materials for such do not yet exist
  • weekly top-level status meetings between Caltrain management, the program management consultant, and the contractor had not been occurring
The list of documents reviewed by the panel in Appendix C would make a juicy FOIA request.

A little bird overheard some discussions that do not appear in the APTA final report, because the report is intended to provide only constructive criticism to help Caltrain out of this mess.  It's even uglier than you could have imagined:
  • Parsons Transportation Group (PTG), Caltrain's prime contractor, does not have the right skills mix to manage complex system integration on 13 different subcontracts
  • PTG is fearful that the commercial terms of the CBOSS contract expose them to legal action by Caltrain, contributing to the lack of transparency
  • Subcontractor General Electric (now Alstom) discovered that simply re-using the existing ITCS product wasn't going to work.  The inter-operable version of the product is incurring massive increases of scope that were not accounted for in the original contract
  • Because of the extent of the changes made to ITCS, the FRA is requiring the same certification and type approval process as for a new PTC system, undermining Caltrain's claim to reusing an off-the-shelf technology
  • The FRA has taken the position that Caltrain is really installing two PTC systems, requiring full testing of both I-ITCS and IETMS (the system that will be used by Union Pacific freight trains on the peninsula corridor)
  • Inter-operability means not only allowing IETMS equipment to operate in CBOSS territory, but also allowing CBOSS equipment to operate in IETMS territory, something that Union Pacific has been concerned about testing thoroughly
  • Poor coordination for accessing an operating railroad for system installation and testing has been and continues to be a bottleneck
  • Additional funding is going to be needed, but nobody knows how much more
  • A change of contract operator (currently Transit America Services, Inc, soon coming up for re-bid) would introduce significant program execution risk
  • Getting all the CBOSS-equipped trains into revenue service could take up to 5 months
The already egregious sum of $231 million to cover a measly 51 route-miles with PTC is about to increase significantly, something you would never guess from the latest CBOSS update provided to Caltrain's laissez-faire board of directors.
Fast forwarding to whatever year it eventually takes place, the RSD (Revenue Service Demonstration) will consist of flipping the "on" switch and transforming rush hour into an epic cascade of software glitches reminiscent of the 1998 MUNI Meltdown.  On that day, we will all know that this CBOSS turkey has finally come home to roost, as was foretold way back in 2009.

10 July 2016

The Capacity Problem

These days, Caltrain is breaking a ridership record nearly every month.  Rush hour trains are running with standing-room-only crush loads, measured by Caltrain's statistics as a percentage of seating capacity.  The most recent ridership counts (tallied during the low-ridership season in the first quarter of 2016) showed several trains running at 125% of seated capacity, even after the addition of a sixth car.  Capacity, or the lack of it, is becoming a problem and Caltrain will need to do more about it before 2020.

A montage of what a Caltrain EMU
by Stadler might look like,
based on a photo by Yevgeny Gromov
The recent award of electrification contracts, including an order for sixteen new six-car EMU trains from rail vehicle manufacturer Stadler, has brought this issue to the forefront.  Caltrain's Chief Operating Officer for Rail, Michelle Bouchard, had to concede in front of the Caltrain board of directors that the new EMUs would initially have a lower seat count than the diesel trains they will replace. The argument was that increased capacity could be achieved by increasing train frequency from 5 to 6 trains per peak hour per direction, and ultimately by lengthening the EMUs from 6 cars to 8 cars, something that can be done to an EMU without loss of performance or track capacity, unlike a diesel train.

Here are some thoughts about the capacity problem.

Capacity is measured in people, not seats.  Measuring passenger load factors as a percentage of seated capacity works well for airplanes, but doesn't quite do the trick for a transportation mode where passengers routinely stand.  The design of a train, including the number of seats, the interior layout, and accommodations for standees (handrails, poles, straps, etc.) has an enormous effect on the level of comfort experienced by passengers when the car operates at "125% seated capacity."  In rail vehicle A, filled with seats and with few places to stand, 125% feels uncomfortably crowded.  In rail vehicle B, with a lower seat count and large areas where passengers can comfortably stand, 125% of seated capacity feels just fine. A better metric of the true capacity of a rail vehicle is the number of seats plus some number of standees per unit of usable floor area (typically 4 standees per square meter); with such a metric, "100% capacity" feels like the same crowding regardless of train design.

Load factors over 100% seated capacity are desirable.  While this may be news to the person crushed between two sweaty people in the vestibule of a rush hour train, sizing the train fleet so that everyone can get a seat during the peak leads to a lot of empty seats running around the system or idling in yards during off-peak hours. This can be mitigated by changing the length of train consists (like BART), but unless trains are designed for this to begin with, it can't be done in daily practice.  Caltrain's new fleet of EMUs will not be easily reconfigurable unless two EMUs are coupled together; plans for this are not evident in the train configurations discussed in the EMU Request for Proposals (6 cars and 8 cars).  With fixed train consists, there is necessarily a sweet spot where a balance is achieved between two undesirable conditions: too many bums and not enough seats during the peak, and too many seats and not enough bums off-peak.  That sweet spot will mean peak load factors should very well be over 100% when measured as a fraction of seating capacity.

LIRR M-7 rail car with 5-abreast,
by Lexcie via Wikimedia Commons
Middle seats are seats, too.  The idea of 3+2 seating (five abreast) is usually batted away with a summary argument that passengers don't like middle seats, but it undeniably results in more seating capacity.  The question is, do passengers dislike middle seats more than they dislike standing? Commuter railroads on the East Coast seem to know the answer: the Long Island Rail Road M-7, the Metro North M-8, and the SEPTA Silverliner V, (to cite only the most modern examples) all feature 3+2 seating areas.  If providing seated capacity is so important, and if load factors are going to be measured as a percentage of seated capacity, then that middle seat is worth an easy 25% additional capacity.  The Caltrain EMU contract could be changed to require 3+2 seating; Stadler has already built a 3+2 bi-level EMU for a Russian client.

Fewer seats can actually increase passenger capacity.  If Caltrain stays with 2+2 seating and a lower seat count, the additional space for standees can provide greater passenger capacity if standees are properly accommodated.  The new EMUs should be configured with poles, handrails, grab handles or straps as necessary to allow standees to travel comfortably when no seats are available.  During the platform height transition period when Caltrain will be operating dual boarding heights (two sets of doors), the number of seats will temporarily drop after seats are removed from the high door boarding vestibules.  This may increase the load factor when measured as a percentage of seated capacity, but it will actually increase passenger capacity by opening up more room for standees.  Comfort may suffer, but only temporarily.

Caltrain should find a way to buy 8 car trains right away.  If some trains are already running at 125% seated capacity in 2016 during the winter low season, they are probably running at 150% seated capacity during the summer.  Seasonal load factor will go even higher if ridership continues to increase between now and 2020 when the new EMUs arrive.  By then, even with the entire Caltrain diesel fleet at six cars per train, the system will likely be bursting at the seams.  The step change in service quality thanks to the new EMU fleet will trigger another ridership increase.  Taking into consideration those three factors (high season peak, continued ridership escalation and better EMU service), it seems likely that six-car EMUs will be overcrowded from day one.  If Caltrain can scrape together another ~$150 million (another 7% of the total tab for modernization) to exercise an option on the Stadler contract, all EMUs can enter service in 2020 as 8-car trains.  Short platforms can be dealt with by prohibiting boarding and alighting from the front or rear cars at the few stations that cannot berth a 200-meter train.  An eight-car Stadler KISS with 2+2 seating will accommodate about 750 seated passengers and another 1000 standees.

10 June 2016

EIR Scoping Comments

The following are scoping comments regarding the San Francisco to San Jose project section of California's high-speed rail system.

System-wide Level Boarding: the blended system is a compromise, less than ideal for HSR and Caltrain.  The successful mixing of local and long distance express service on "primarily two tracks" will require the utmost coordination and reliability in order to satisfy the expectations of commuters and statewide travelers.  The key to punctual operation is to ensure that station dwell times are short and predictable, something that cannot be achieved with today's 8-inch-above-rail Caltrain platforms. The EIR should study a system-wide conversion to level boarding, as facilitated by Caltrain's procurement of dual boarding height EMUs.  Level boarding does two important things for HSR: it ensures that Caltrain commuter trains get out of the way of HSR in timely and reliable fashion, and increases the average speed of Caltrain services, unlocking additional track capacity.  The frequent service and punctuality that travelers will expect of HSR cannot be achieved without level boarding.

Fast-Slow-Slow-Fast Overtake Sections: four-track overtake sections should be configured with overtaking tracks on the outside and slow tracks in the middle (fast-slow-slow-fast) with central island platforms for Caltrain.  The major advantage of this configuration is to allow Caltrain to single-track as needed during service disruptions without fouling the express tracks.  While the track centers will need to shift outwards to make space for island platforms, the resulting curves can be built with very large radii and very low superelevation, with no impact to passenger comfort.  The station footprint requirements for fast-slow-slow-fast are minimal due to one island platform being narrower than two side platforms.  Examples of the fast-slow-slow-fast configuration exist in Sweden and Australia.  Given the operational advantages of this configuration, the EIR should study it as an alternative for any proposed four-track overtake sections.

Grade Separations: should any new grade separations be contemplated as part of the blended system, these should be engineered "not to preclude" the future addition of a third and fourth track. The peninsula corridor right-of-way is so generously sized that building new two-track-only infrastructure is short-sighted and potentially wasteful.  Even if grade separations are initially built for two tracks, the EIR should study full-sized bridge abutments and retaining walls as needed to support future expansion, even if such expansion is not part of the project scope.

Dumbarton Connection: some form of rail service in the Dumbarton corridor has been studied for decades and is likely to be implemented sometime in the next half-century, given regional development and transportation pressures.  Any changes to Dumbarton Junction that might be studied in the EIR should be engineered "not to preclude" a future seamless Dumbarton rail corridor connection, including a grade-separated flying junction for at least the southbound track.  While this may carry the political appearance of leaving the door open to HSR via Dumbarton and Altamont Pass, such political considerations should not be used as an excuse to sabotage the possibility of an efficiently designed rail junction with the Dumbarton corridor.

Mid-Peninsula HSR Stop: the EIR should study the possibility of a mid-peninsula HSR stop located in Redwood City.  With a common platform interface standard shared by HSR and Caltrain, the impacts could be quite minimal.  In the long term, a four-platform-track elevated (i.e. grade-separated) station should be considered for this location.

Platform Track Speeds: high-speed express trains currently run past Caltrain platforms at a maximum speed of 79 mph, with only a painted yellow line to warn people on the platform to stand clear.  Electric express trains operating at 110 mph (on primarily two tracks, and hence running past Caltrain platforms) are both faster and quieter, and have a higher chance of startling people standing on the platform, possibly causing them to lose their balance and fall towards the passing train.  The EIR should account for the impacts of constructing wider Caltrain platforms with ample clearance to stand clear of passing trains, with appropriate visual and aural warnings.

Hold Out Rule: the EIR should include a study of the impacts of modifying the few remaining stations (South San Francisco, Broadway, Atherton and College Park) that still have narrow at-grade center platforms, where no trains may move through the station while another train is stopped.  The hold-out rule is a disruptive and antiquated operational constraint that is contrary to the needs of a fast, flexible and high-capacity blended rail system; the cost of eliminating this constraint is minuscule in relation to the overall investment being contemplated.

Blended System Southern Boundary: San Jose Diridon, while an important HSR stop, is not a natural terminus for Caltrain services.  Large population densities in the vicinity of the Tamien, Capitol and Blossom Hill stops that are currently located on the "Gilroy Extension" of Caltrain should be served more regularly.  Moving the southern boundary of the blended system beyond Tamien to Blossom Hill would not only meet latent commuter demand on the congested 101 corridor, but also free up scarce platform capacity at San Jose Diridon by avoiding the need to turn any trains there.  For this reason, the EIR should consider the idea of terminating Caltrain service at Blossom Hill.

CEMOF Alignment: Caltrain's Central Equipment Maintenance and Operations Facility (CEMOF) was constructed with a double reverse curve that severely limits train speeds near San Jose, if an at-grade solution is contemplated.  Because achieving fast San Francisco - San Jose times is important to HSR's compliance with the terms of the HSR bond act, the EIR should study the possibility of reconfiguring the track layout of CEMOF, moving the main tracks from the east side of the facility (the slow double reverse curve) to the west side of the facility (a faster alignment, with only one shallow curve).  This would effectively exchange CEMOF yard tracks 8 and 9 with MT-2 and MT-3.  Personnel, equipment and materials can enter the facility through a tunnel under the main tracks, as is already done for access from the east.

Newhall Yard: VTA owns a large former UPRR freight yard in Santa Clara, currently slated to be used as a future maintenance facility for the BART to Silicon Valley project.  In the event that the BART Phase II project is value-engineered to terminate at San Jose Diridon (without a redundant and duplicative extension that parallels the blended system to Santa Clara, and with vehicle maintenance requirements met by BART's amply sized Hayward Maintenance Complex), the EIR should study the possibility of using Newhall Yard as a maintenance facility for HSR.

07 May 2016

Caltrain Has a Dwell Time Problem

Actually, Caltrain has two dwell time problems. The first is that station dwell times are too long, and the second is that station dwell times are too unpredictable.  Both of these problems will prove fatal to the blending of Caltrain and HSR services on "primarily two tracks."

To help visualize why, let's use position-versus-time string diagrams, often discussed on this blog.  Imagine trains following each other on a single track that runs from San Jose to San Francisco (ignore the other direction for now).  This red line is a local train making a lot of stops.  It leaves San Jose, and a while later arrives in San Francisco.  If you looked really closely you might see the individual station dwells, small horizontal kinks that occur whenever the train is stationary and time passes, but when you squint, it looks pretty much like this:
Every once in a while, this local train comes to a station where Jane, a wheelchair user bound for San Francisco, would like to board.  Because we don't have level boarding, getting Jane on board the train involves manually deploying lifts or ramps to ascend the several steps from the platform into the train.  Conductors must help Jane through the mechanics of the boarding process, which can easily take several minutes but feels like an eternity, even for Jane.  Timetable planners allow for riders like Jane by making sure that no other trains are scheduled right behind each other, to absorb these randomly occurring super long dwells without causing a train traffic jam.  They call it padding.  Here's what padding looks like, in pink:
This being a blended system on "primarily two tracks," we've got express trains and even high-speed trains using the same track as Jane's local.  A faster train looks like this blue line:
The blue line is steeper because the express train can cover the same distance from San Jose to San Francisco in much less time.  Here comes the express behind the local:
The timetable planners don't want the express to be delayed.  That's why they left a big gap between the trains, giving the local a good head start out of San Jose so that the express won't catch up to it before San Francisco.  Alternately, here is the local departing San Jose right behind the express:
Once again, a big gap opens up behind the express because the local is so much slower to arrive in San Francisco.  Now it's rush hour, and this is what "blending" soon looks like (not to scale):
In one hour, six trains can arrive in San Francisco.  Our string diagram is full of gaps, which means we are making very poor use of the capacity of our single track.  How do you fix this?

First, you electrify Caltrain.  While this isn't cheap, one of the main advantages of electrification is that EMUs start and stop much more quickly, so that on average, a local can get to San Francisco several minutes sooner while still making the same station stops.  The local will have a higher average speed than it did before.  Compare:
See how the new EMU local train shows up as a steeper line?  That's because it spends less time moving between stations.  (Note to Atherton: electrification is not just an emissions thing.  Tier IV diesel trains can't pull off this neat trick like an EMU can.)  Now this is what the "blended" rush hour looks like:
If you compare it carefully to what we had before, we can now fit eight trains in the span of one hour, instead of six, because those dreaded gaps are shorter.  By increasing the average speed of the locals, we were able to squeeze in more trains (and more passenger capacity).  Caltrain seems content to declare victory and live like this happily ever after.  This is what they envision as the "blended system".  Whenever Jane decides to ride the train, the pink padding still ensures that following trains aren't delayed too badly.

It's better, but still kind of mediocre.  Especially for Jane.

What if the local train could spend less time standing still at each station?  Dwell time can be reduced by level boarding, a step-free and gap-free configuration where you simply walk on or walk off the train, just like when you ride BART.  For a given number of passengers getting on and off the train, level boarding shaves off about 1/3 of the station dwell time since they can all shuffle on and off more quickly and seamlessly.  The magic of reducing dwell times is that while the train's actual speed is no higher, it still gets to San Francisco sooner, because it saved a few seconds during each station stop.  A few seconds here, a few seconds there, and pretty soon you're talking several minutes.  The average speed went up without the actual speed increasing!  The string for an EMU local with level boarding now looks like this:
If the local arrived in San Francisco ten minutes earlier thanks to electrifying Caltrain, it can arrive another five minutes earlier than that by having level boarding at all stations.  Electrification saves time between station stops, and level boarding saves time during station stops.  The two work together as perfect complements to each other.

The diagram above is actually wrong, and here's the second amazing thing about level boarding: Jane can get on and off the train like everybody else.  Not only does this give Jane the dignity and equal treatment that she deserves, but it saves everybody else the grief of those randomly occurring Jane delays.  Because dwell times are now predictable, timetable planners can get rid of the padding they applied in case Jane wanted to ride before.  Like this:
If you like probability distributions, here is the effect of level boarding on the probability distribution of dwell time:
Caltrain commissioned a study of station dwell times, which found that across a sample of 5149 station dwell observations, the median duration from wheel stop to wheel start was 49 seconds.  The median excludes abnormally long dwells, such as those occurring when Jane wants to ride.  The average dwell time does account for Jane and is 58 seconds, practically an eternity.  That was back in 2010.  Today, with the system bursting at the seams, average dwells are getting so long that the timetable was recently adjusted to make chronically late trains into slower on-time trains.  With level boarding, typical dwell times could easily be cut to 30 seconds.

Level boarding really improves the situation for rush hour:
We're really cooking now.  We can squeeze 12 trains through in one hour on the same track.  That represents a massive capacity increase, with the combined effect of reduced and predictable dwell times providing a similar benefit as electrification alone did.

Caltrain staff just doesn't seem to get this, and they are certainly not helping their board of directors understand the issue. They think of level boarding as primarily an optional comfort feature. Here is their view of level boarding, from a recent board meeting quarterly update:

First of all, they don't even call it level boarding. Dual doors!  What a pain!  Requested by interloping stakeholders, or imposed by those annoying HSR people!  Ew, it's so complicated!  It costs $30 million to equip the new fleet!  It's almost as if they are disowning the very idea of level boarding, and reluctantly trying "not to preclude" some unspecified future decision because this stuff is just too hard to think about.  Presented this way, you couldn't blame the board or the public for thinking this is a stupid idea.  Where's the upside?

The upside is this: dual doors are the only realistic path for Caltrain to achieve level boarding, and level boarding is the only way that the blended system can work on "primarily two tracks."

This issue cannot be taken lightly, because the next opportunity to start a Caltrain conversion to level boarding will not occur until 2050, when the new fleet reaches the end of its useful life.  That's because the new fleet, as about to be ordered, cannot provide level boarding at a platform height of 25 inches.  The entire system would have to be shut down for the trains to be modified and all platforms to be rebuilt at that height.  So, doing nothing today and blindly kicking the can down the road until 2050 is not an option.  A prudent and strategic $0.03 billion down payment for a gradual transition to level boarding is minuscule as a fraction of the $2.2 billion modernization budget, and unlocks great potential for quicker and more punctual commutes as soon as the next decade.

Dual doors are a customization that amounts to less than 5% of the price tag for new trains ($30 million out of $648 million bid price).  They can hardly be used as an excuse for the massive increase in the cost of Caltrain modernization.  They will help to address Caltrain's dwell time problem.

Caltrain has a dwell time problem.  The first step is for everyone (staff, board and public) to understand it.