March 2025 Open Thread

The comment section from the last post is about to overflow, so here is an open thread to keep the discussions going. Some noteworthy developments fished out of the previous comments:

• Caltrain's corridor-wide grade separation strategy continues to evolve towards its final form, with a prioritized list of grade separations due for adoption this summer. Of note, grade separations are now allowed 2% grades without a design exception, which removes the need to design an entire 1% project before seeking the exception. Steeper grades are a good start for shorter grade separations, but we also need to reduce freight train speeds to 45 mph throughout the corridor to tighten up vertical curve radii. A freight train requires the same vertical curve radius at 45 mph as a passenger train at 110 mph, such that freight speed limits any higher than 45 mph result in freight-driven designs that are longer and more expensive to build. An important but neglected part of the grade separation strategy should be to reduce the freight train speed limit from 50 mph to 45 mph.
   
• Speaking of grade separations, costs continue to rise out of control, with the Broadway project in Burlingame (see agenda item 11 of the March 3rd city council meeting) flirting with $900 million. It's not just inflation. A grade separation cost model discussed a few years ago predicted that, after adjusting for inflation, the Broadway project should cost $120M all-up, including the "soft cost" category that today forms a metastasizing cancer on these projects. The city is now considering deleting the Broadway station (not a bad decision, due to proximity to Bvrlingame) to bring costs down to the still eye-watering sum of $600M. This is a prime example of the transportation industrial complex's capture of a project designated as safety-critical, where cost becomes no object because you just can't put a price on safety. In this abject fleecing, the city and Caltrain are just along for the ride.
   
• Development of the BEMU continues, in spite of the looming "fiscal cliff" where one of the most logical cost cutting moves will be to suspend Gilroy service and dispose of the diesel fleet and its attendant operating & maintenance expenses. The BEMU has fewer seats (280) and more batteries (2.3 megawatt-hours) than previously understood, making it even more of a turkey for the $80M pricetag.
   
• On the bright side: Caltrain's EMU service is holding up nicely!  Well done to all involved. Ridership should continue to increase as the freeways rapidly return to pre-pandemic levels of congestion misery. The way this works: 101 overflows onto 280, which overflows onto Caltrain. 280 is starting to get congested again, which augurs well for Caltrain.

Deadly Caltrain Underpasses

The recent storms demonstrate once again that Caltrain underpass flooding is a clear and present danger to the public. Deadly is no understatement: while only harrowing water rescues occurred in the 31 December 2022 atmospheric river, two people lost their lives in the flooded Hillcrest Boulevard underpass in Millbrae on 23 December 2021.

Poor "split" grade separation designs that only marginally lower the height of the tracks compared to fully elevated tracks are sure to kill again if Caltrain and surrounding communities continue to build more of them. (lookin' at you, Redwood City!)

Harbor Boulevard, Belmont

 

Ralston Avenue, Belmont (M.M. Parden photo)

42nd Ave, San Mateo (M. Sly photo)

Hillcrest Boulevard, Millbrae (December 2021)

News Roundup, October 2022

CBOSS Dumpster Fire Update: the CBOSS case is still making its way through San Mateo County Superior Court (under case file 17CIV00786). The trial was held in April through June of this year, and closing briefs are due in December. Closing arguments are currently scheduled to be made in court on the 5th of January 2023. The latest kerfuffle is over a post-trial Caltrain/Parsons motion to seek punitive damages from Alstom for intentionally, not just negligently, lying about the status of the project based on testimony given during the trial.

Trains Without Wires: Caltrain held a VIP invitation-only unveiling of the new EMUs in San Francisco on September 24th. Four trainsets (serial production #2 - #5) have now been delivered and will collect dust (graffiti?) for a couple of years because the electrification of the corridor is far from done. The new trains were hauled to San Francisco by diesel power.

New Palo Alto downtown
grade separation

Stirring Things Up In Palo Alto: Caltrain recently briefed the city on their plan to replace the ancient bridge over the San Francisquito Creek. This is precipitating a sudden change to the city's years-long policy of kicking the can down the road on what to do about a future grade separations at downtown Palo Alto. While everybody seems to assume the bridge and grade separation projects are necessarily linked, they are not! The solution is pretty darn obvious: replace the Palo Alto Ave crossing with a new grade separation at Everett Ave, which would connect downtown to El Camino as shown in the sketch at right.

1. Permanently close and demolish the Alma bridge over University Ave, instead connecting Alma to University via the existing cloverleaf ramps reconfigured as a signalized intersection.
2. Build a new downtown elevated grade separation viaduct and platforms through the existing station parking lots, along the original track alignment that existed before the University Ave grade separation was opened in 1940. This viaduct would be open underneath, providing station parking, bus platforms, pick-up/drop-off areas, and other station amenities. Bonus: the new straightened track alignment removes a speed-limiting double reverse curve in the tracks.
3. Cut over the trains to the new viaduct and elevated station. 
   
4. Extend Everett Ave under the elevated tracks to the existing intersection at El Camino Real and Quarry Rd, also picking up a new connection to the convoluted and inefficient bus loop. Bonus: bus service is greatly sped up to/from El Camino, Stanford and downtown by avoiding time-consuming looping routes.
5. Permanently close the grade crossing at Palo Alto Ave.
6. Demolish the old University Ave rail bridge, remove the old cloverleaf ramps, and bring the University Ave / Alma intersection back up to a grade level signalized intersection.

This grade separation approach is completely decoupled from whatever happens with the San Francisquito bridge.

More CEQA Lawsuits Flying: the recent certification of the HSR San Francisco to San Jose EIR precipitated several new CEQA lawsuits. Brisbane and a private developer are upset about the sprawling HSR "light" maintenance facility planned in the city, and its impact on the planned Brisbane Baylands development. Millbrae also got in on the action due to a clash between its development plans and the planned expansion of the station footprint for HSR. Unfortunately, the Sacramento Superior Court does not allow free access to case files, so details are hard to obtain.

Capital Spending for Better Service

Wouldn't it be great if you could quantify the service benefit of capital improvements, to compare and prioritize them by how much better train service results?  We can, and using our handy Taktulator, we will. This service pattern evaluation tool was formulated around time-based service quality metrics. We use it to explore future improvements to the peninsula rail corridor.

Today's 2022 Timetable: 94 service points -- The current peak schedule with four diesel trains per hour features very generous padding and SF - SJ trip times ranging from 66 minutes (express) to 99 minutes (local). The less-than-100 score indicates that service quality has dropped since 2011 when there were five trains per peak hour. The Taktulator score is calibrated such that the 2011 Caltrain timetable scores exactly 100 points.

Caltrain's 2040 service vision foresees eight trains per peak hour per direction (not counting HSR). Let's start with a service frequency of 8 trains per hour-- except for the sake of exploring and quantifying the value of capital improvements, we'll start from a hypothetical case that will never happen: eight trains per hour of today's diesel service, making all local stops.

Hypothetical diesel all-stops local, 8 tph: Score = 109 service points (+16%) -- The doubling of hourly frequency improves the service score by 16%, despite each train being slower. The extra time riding an all-stops trains is more than offset by the much shorter wait time at the station. For example, maximum wait times in Belmont plummet from one hour to just 7.5 minutes. Unfortunately, this service pattern would take an unrealistic 32 trains to operate, because each train takes 94 minutes to go between SF and SJ. The hypothetical scenario still illustrates the magnitude of the effect of doubling frequency.

Add electrification: Score = 121 service points (+11%) -- Electrification is worth another +12 points relative to diesel, thanks to the shorter trip times that come from the higher acceleration capability of EMUs. Those savings accrue to a full ten minutes between SF and SJ for an all-stops local. Station dwell times are still booked at 45 seconds, a longer duration that reflects the lack of level boarding. Thanks to the faster trip times, the fleet requirement has dropped from 32 trains to 28 trains. Service speed saves money, not just on fleet size but also by increasing the hourly productivity of train crews (in terms of passenger-miles served).

Add Redwood City hub station: Score = 131 service points (+8%) -- If trains cannot pass each other, there is no room in such a frequent timetable for express service. A new four-track station at Redwood City, where express trains can overtake locals on opposite sides of the same station platform (so that passengers may transfer seamlessly between local and express) gives the best of both worlds: frequent service AND express service. For now, we'll assume this station has only two-track approaches, requiring trains to arrive and depart serially. In practice, this means every local must wait more than 5 minutes or the equivalent of two signal headways to let the express catch up before RWC and then pull ahead after RWC. The stopping patterns start to look like Caltrain's 2040 service vision.

Add Redwood City quadruple approach tracks: Score = 138 service points (+5%) -- If quadruple tracks are added approaching Redwood City from the north and south, then local and express trains can make parallel moves into and out of the hub station, removing the requirement for every local to wait there for five wasteful minutes. To unlock this benefit, the quadruple track overtake section needs to extend to one station on either side of RWC, so every local train can make productive use of those five minutes. In the Taktulator, we simulate this by having every local train stop at San Carlos and Atherton, which (despite its closure) stands in for a new Fair Oaks infill station at 5th Avenue. This suggests a hub station is about 1.7x more effective if it forms the center of a three-station quadruple track section. Having fully half your trains save five minutes is a huge service improvement!

Add level boarding: Score = 147 service points (+7%) -- Where electrification saved time in motion, level boarding saves time at rest by shaving 15 seconds of dwell time at each station, as step-free access smooths passenger boarding and alighting. Level boarding gives not only short dwell times but predictable dwell times (for example, wheelchairs don't take longer to board) so we can also tighten up the padding margin in the timetable, cut in this example from 12% to 7%. Interestingly, the end-to-end corridor times fall below a threshold that allows turning a train sooner, reducing fleet requirement from 28 to 24 trains. This isn't necessarily an effect of level boarding itself, and only illustrates that a series of small improvements can result in a discontinuous benefit when a certain threshold is reached.

Add SF Downtown Extension: Score = 250 service points (+70%) -- There are more jobs (over 100,000) located within a half mile of the Transbay Transit Center than there are jobs within a half mile of every other Caltrain station combined. This makes downtown SF a dominant node if added to the system, a fact that is reflected in our census-based weighting of available trips. No other improvement comes close.

Here is how these service improvements stack up against each other, plotted as the logarithm of the ratio of after/before scores, which gives you their relative impact. They can be constructed in a different order than imagined above, but the relative proportion of each improvement should remain approximately similar:

Bar graph of the relative service quality improvement of Caltrain capital projects

Here are some key takeaways:

1. Grade separation projects do not improve train service. Exceedingly rarely, they do prevent a train delay, something that is not captured in this analysis. On the basis of the time metrics of a typical trip, however, the service improvement of grade separations is ZERO. This should factor strongly into how many billions we are collectively willing to spend on them relative to the other capital improvements discussed here.
    
   
2. The benefits of electrification alone (without other improvements) are mediocre at best. On the basis of our time metrics, service quality is only improved by about 11% relative to an equivalent diesel scenario. Caltrain can't just finish the electrification project and call it good enough.
    
   
3. The Redwood City hub station now in the planning stages is surprisingly beneficial to service quality. While packaged and sold as a grade separation with a bonus of expanding the train station, it is hard to overstate the service quality benefit of the new hub station. Even as planned by Caltrain (with two-track approaches from the north and south) the new station produces nearly as much service improvement as the entire electrification project.
    
   
4. The Redwood City hub station as planned by Caltrain with two-track approaches is operationally ineffective. It can be juiced up to 1.7x more benefit to service quality by making it the center of a four-track overtake facility spanning just three stations: San Carlos, Redwood City and a new Fair Oaks infill station at 5th Ave. The southern portion of this four-track facility already exists today. Together with 4-track approaches, the Redwood City hub improves service quality by a greater proportion than the entire electrification project! That's why it is critical that planning for the Redwood City grade separations allow for four tracks throughout.
    
   
5. Level boarding provides over half the service quality improvement of electrification, and is likely to be a much cheaper capital investment. However, it makes sense to do it after the hub station.
    
   
6. The downtown extension in San Francisco will be a game changer for service quality. The transportation industrial complex knows this and will make us pay dearly for the DTX project. However, the additional billions for the PAX (Pennsylvania Avenue Extension, a city-desired grade separation) add absolutely nothing to service quality, and should never be allowed to be bundled with the DTX project. Every capital dollar should improve service quality.
    
   
7. The Redwood City hub station (with four tracks, not two!) is worth one fourth of the service benefit of the DTX. That means we should (a) not be shy about spending capital dollars to build it and (b) stop selling it as a grade separation, because that isn't the story here-- it should be about a new infill station, seamless transfers, and better service quality system-wide.
   

As always, the analysis provided here can be quibbled with and improved upon, and you are encouraged to "do your own research" by trying out your own service patterns in the Taktulator.

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.

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.

Thoughts on Grade Separations

The emerging Caltrain business plan is broaching the issue of grade separations, a decadal process that has been underway, well, for decades. We're already 63% of the way there today, with another dozen new grade separation projects in various stages of planning or construction. Achieving a reasonable level of grade separation for the peninsula corridor is estimated to cost $8.5 - 11.1 billion, a shockingly large sum that we'll just round to $10 billion. As we try to grasp the enormity of that figure, here are some contrarian thoughts:

1) Don't spend train money on car projects. The benefit of grade separations accrues primarily to automobile travel, with the elimination of gate down time. An intensive grade separation program can eventually unlock additional operating slots for more trains and eliminate the occasional incident, yielding benefits to train riders. Some grade separations are necessary, such as when expanding to four tracks. In the short term, however, the greatest benefit is the removal of an inconvenience to drivers, which in our car-centric society is held as a worthy goal seemingly regardless of cost. Rail dollars are a lot scarcer than road dollars, especially in this era of federal disengagement, so the last project we should spend them on is a project that facilitates car travel with little improvement for train riders. Rail funding should be used to make real and measurable improvements to train service, a standard by which most grade separations rate poorly. So you still want a grade separation? Build it with road funding.

Anticipated gate down times,
under various scenarios in the
Caltrain business plan

2) Quit whining about gate down time. Caltrain put together a nice summary of gate down time, the number of minutes per hour that grade crossing gates block traffic during rush hours. Today the average is 11 minutes, and under future growth scenarios it could increase to 17 - 25 minutes, with a few crossings faring worse than average. If that sounds intolerable, think about a typical roadway intersection with a traffic light. If both roads are equally important, the "gate down time" of a traffic light is 30 minutes. If one road is more important, the lesser road (for example, Ravenswood Ave where it meets El Camino Real in Menlo Park) sees "gate down time" well in excess of 30 minutes, let's say 40 minutes per hour. Nobody is clamoring to grade separate the Ravenswood / El Camino road intersection. There's an obvious double standard here, and the guidelines for what qualifies as unacceptable delay should be set the same way as they are for the grade separation of a road intersection. Gate down time should only rarely, if ever, be the reason to build a new grade separation.

3) There are few economies of scale in grade separation. Doing them all as a package does not save money. The process we have, where local jurisdictions often exert tight control over every aspect of design and construction, does not lend itself to a one-size-fits-all approach. Each grade separation is different. Grade separation designs do not depend on each other in the majority of cases where they are widely spaced. While a corridor-wide strategy is important to have, the execution of that strategy and the securing of funding is inherently a city and county issue. If we are going to have a corridor-wide funding approach, it must go hand-in-hand with taking away local control. Jurisdictions that insist on local control should be left to figure out the funding on their own. Palo Alto, where interminable and futile discussions of tunnels continue to this day, should not be allowed to control the design process if their project is paid for through a corridor-wide funding measure.

4) If $10 billion is an okay expense, then there are far better ways to spend it. Especially with rail money at stake, there are much better ways to spend $10 billion than by building a lot of grade separations for cars that produce zero improvement to train service. There are a lot of good investments that should be made to improve the amount and speed of train service:

• Extend all platforms to 8-car length. If you put all the platforms that Caltrain ever built in the last 20 years end to end, they would stretch about 5 miles long. This is not an expensive project; it can be done for about $0.05 billion. It should already be underway, but inexplicably isn't.
• Convert the entire train fleet to 8-car EMUs, starting by exercising the rest of the existing Stadler contract option of another 59 cars, increasing the fleet to 24 trains. The diesels are retired from the peninsula, which is a condition for starting any level boarding projects. This costs about $0.4 billion.
• Convert the entire system to level boarding to speed trips and improve punctuality. Depending on how this is done (high platforms or low platforms, or some combination thereof) and over how long a period of construction, this would cost about $0.5 - 1 billion.
• Build a new EMU maintenance and storage facility near Blossom Hill (San Jose) and extend frequent electrified service through all of San Jose. Including any extortion by UPRR, the owner of the tracks, this ought to be feasible for less than $1 billion.
• Build a new transit center in Redwood City to enable cross-platform transfers between locals and expresses. Call it $0.5 billion, and throw in the downtown grade separations for another $0.5 billion to allow four tracks.
• Expand the EMU fleet to enable 8 train per hour peak service. Expanding the fleet to 32 trains would require another 64 EMU cars, for about $0.5 billion.
• Extend the platforms at highly patronized express stops to 12 cars in length, and extend expresses to 12 cars. This would require extending about half the fleet by 4 cars, or another 64 EMU cars. Including platforms this might cost about $0.8 billion.

This isn't an exhaustive list, but unlike grade separations, all of these projects have immediate and measurable positive effects on the quantity and quality of service provided to riders. This list achieves most of Caltrain's "moderate growth" scenario but without HSR. The tally for all of these projects is still less than $5 billion, so if $10 billion for grade separations sounds at all palatable, this list ought to be a no-brainer.

Grade separations are nice, but their cost and benefit should be weighed very carefully on a case-by-case basis. The cost should be borne by who benefits. The business plan process will hopefully create the framework to have the difficult conversations about what not to pay for with rail funding. Grade separations should be built with highway funding unless there is a clear and measurable benefit to rail service.

Palo Alto: Designing in a Vacuum

Palo Alto is continuing the fraught public process of winnowing down the feasible and acceptable options for grade separating the four remaining rail crossings. Having hired an engineering consultant, the city is busily making plans for railroad land that doesn't belong to it and over which it has no jurisdiction.

The fancy renderings from a recent meeting, envisioning a tunnel, a trench, a hybrid embankment, or a viaduct, invariably show expansive new landscaping when construction is finished. This is reflective of the ample railroad land available through most of Palo Alto. Caltrain's land is typically about 100 feet wide, excepting a few short sections of the corridor near Southgate and Peers Park that are just 60 feet wide. South of those narrow spots, there is plenty of room to accommodate four tracks (about 75 feet required) if needed in the future, no matter what the pot-stirring local press may say.

Palo Alto's planning process thus far seems to have missed these important facts:

1. Caltrain's nascent business plan envisions ambitious expansions of service in the next two decades, growing far beyond the initial goal of electrification. Service planning thus far strongly suggests (pp. 64-67) that new overtake tracks will be needed approximately from south of Peers Park to the Mountain View border. The additional tracks in south Palo Alto, featured in all remaining options (p. 34), would allow express trains to pass local trains.
    
2. In other cities to the north and south where Caltrain has become directly involved in the planning process, it has levied a requirement that city-generated grade separation designs preserve the future option of adding overtake tracks, expanding the corridor from two to three or four tracks. Two examples:
    
• Whipple Ave in Redwood City, where the city recently hired Caltrain to lead the planning effort. On page 138 of the October 1st, 2018 city council meeting agenda, a letter from Caltrain states: "... the Project Study Report must include at least one design option that accommodates the potential overtake. In this context, "accommodate" is understood to have the following minimum threshold of meaning: the grade separation design maximizes the preservation and configuration of existing right of way such that overtake tracks could be built later with no or minimal right of way acquisition; the grade separation design does not force future overtake tracks to be built in a way that substantially increases their cost and complexity."
   
• Rengstorff Ave in Mountain View, where the city recently hired Caltrain to lead the preliminary engineering and environmental clearance effort. On page 105 of the December 2018 JPB board meeting agenda, we read that "the design will consider and accommodate Caltrain / high-speed rail blended system improvements and be designed to allow for up to four tracks."

In practical terms, this adds a new constraint to Palo Alto's grade separation deliberations. We can reasonably infer that Caltrain will require at least the Charleston / Meadow grade separation to be engineered for four tracks, or at least not to preclude four tracks. The sooner this constraint is incorporated into the city's planning process, the less anguish and recrimination there will be in arriving at an acceptable design.

When planning construction on someone else's land, it helps to know what the owner wants.

Thinking Big in Redwood City

The architecture of Amsterdam Bijlmer
(photo by tataAnne) could represent
the future Redwood City station.

In a seamless transportation network that runs on a regular clockface schedule with timed, well-coordinated transfers, connecting nodes play a key role. Redwood City has natural potential as a connecting node, being located approximately at the midpoint of the peninsula rail corridor, serving as a logical transfer point between local and express trains, serving as the entry point to the peninsula from the future Dumbarton rail corridor, and being in of itself a significant destination with extensive connecting bus service and a willingness to grow.

With Redwood City currently renewing its interest in grade separations, it's important to think big and to re-imagine the station as a key node in the Bay Area's transportation network.

Start with a good timetable

Using our handy service pattern generator, let's see what we could do if we organized a blended system that made Redwood City a key transfer node. When you make a business plan, the first thing to be crystal clear about is: what is your product? In Caltrain's case, the timetable is the product, and all these stations and tracks should only be built as long as they contribute directly to delivering a quantifiably better timetable for the ordinary rider. Building a major new station in Redwood City isn't about trite superlatives like "Grand Central of the West," but simply about efficient and seamless coordination of timely and reliable ways to get from point A to point B.

Let's set some ground rules for our timetable:

• Caltrain expresses will operate every 10 minutes on a regular clockface schedule. A base 'takt' of 10 minutes reduces gracefully to 20 minutes or 30 minutes in the off-peak.
• In Silicon Valley, there will be no skip-stop service because the population and jobs are evenly sprawled. Every station in Silicon Valley needs to be served frequently, doing away with the ridership distortions induced by the Baby Bullet effect.
• In San Mateo county, where stop spacing is closer, slower local trains will operate every 20 minutes. These local trains will meet the express at Redwood City, before turning back north.
• Dumbarton service will operate every 20 minutes, meeting the express at Redwood City with little or no wait to transfer to trains on the peninsula corridor, before turning back towards the East Bay.
• Because the overall pattern repeats every 20 minutes, HSR will operate 3 trains per hour rather than the planned 4. Otherwise, there is a harmonic mismatch between the HSR frequency and the Caltrain frequency. 4 HSR trains per hour in a clockface timetable forces the base 'takt' to increase to 15 minutes, which is not desired.
• If we're going to make Redwood City a major node, it certainly rates HSR service, so we will create a new mid-peninsula stop for HSR.

This is the resulting timetable (see also additional data on service pattern), shown here for one hour in the southbound direction only (the northbound side is symmetrical). Colors denote the 10-minute Caltrain express, the San Mateo local, Dumbarton service, and HSR.

Notice the express arriving at Redwood City at 7:43 meets the Dumbarton train departing at 7:44, and the local arriving at Redwood City at 7:52 meets the next express at 7:53. Every ten minutes there is a cross-platform transfer, alternating between express-to-Dumbarton and local-to-express. Counting both directions, a cross-platform transfer occurs at Redwood City every five minutes!

Implicit in this timetable are a number of other capital improvements besides a new Redwood City station, such as overtake tracks in various locations along the corridor (highlighted in yellow in this view of the timetable... and while we're here, look how much less yellow is needed if HSR uses the Dumbarton corridor via Altamont Pass). It's important to remember that there is no formulation of the blended system that avoids the need for overtake tracks, unless one is willing to push slower trains into station sidings to sit for at least five minutes while a faster train catches up and pulls ahead. If you are a Caltrain rider, you should be wary of the cheapskates at the HSR authority who want to do this to your commute.

Deriving the functional requirements for the Redwood City node

To enable this timetable, we need the Redwood City station to have the following attributes:

1. Four platform tracks serving two 400-meter long island platforms to facilitate both northbound and southbound cross-platform transfers of very long, high-capacity trains.
    
2. Platforms centered on the best cross-town corridor, namely Broadway, for convenient access to and from local destinations on foot, by bike or scooter, by bus, or using the planned Broadway Streetcar.
    
3. A turnback track that enables certain Dumbarton corridor trains to originate and terminate in Redwood City, without fouling other train traffic, long enough for an EMU-8 train.
    
4. A turnback track that enables the San Mateo local to turn back in Redwood City, without fouling other train traffic, long enough for an EMU-8 train.
    
5. Elevated grade separation of all downtown Redwood City crossings, enabling free flow of pedestrians, bikes and vehicles under the rail corridor and including the re-connection of streets currently cut off by the existing configuration (e.g. Hopkins and James).
    
6. Bus facilities placed directly under the train platforms for seamless connections without the need for an umbrella. Same for an eventual Broadway Streetcar.
    
7. No mezzanine level. Mezzanines needlessly drive up the size and cost of stations, and impede and complicate vertical circulation. Street level can fulfill all the functions of a mezzanine, including ticket sales, wayfinding, waiting, retail, and dining.
    
8. The shortest and fastest possible vertical circulation (stairs, escalators, ramps, and elevators) using a U-shape viaduct cross section to avoid deep and vertical-space-wasting bridge structure. This helps with transferring quickly between the two island platforms, as would be needed for example to continue from the Dumbarton corridor south to Silicon Valley.

The footprint of such a station is not small. However, Redwood City has plentiful available railroad and transit district land, and the street level interface of such a station can be integrated into the city's street grid, opening up cross-corridor access and avoiding a wall effect. The aging Sequoia Station shopping center, with its wasteful surface parking, can be demolished and redeveloped to make room for an expanded station. Station parking can be moved underneath the approach structures, protected from the elements.

One possible station layout

An optimal station layout has four tracks, with the outer tracks for HSR and express commuter trains. The middle tracks are for commuter trains, and allow both northbound (Dumbarton) trains and southbound (San Mateo local) trains the opportunity to turn at Redwood City without impeding the flow of express traffic. The width of the structure is about 130 feet, as shown in the cross section below:

The northbound express track (Track 3) is tangent. The northbound island platform is 400 x 10 m. The center commuter tracks (Tracks 1 and 2) have curves that are not laid out in detail; this detail does not matter since any train that uses these tracks would slow and stop at Redwood City, using standard trackwork and turnouts. The southbound express track (Track 4) is the tricky one: it wows around the station, passing the southbound island platform on a 7500 m radius curve with approximately 1.5 inches of superelevation (not enough to matter for platform lateral tolerances). This track consists of a double reverse curve with six spiral transitions (tangent, spiral, curve, spiral, tangent, spiral, platform curve, spiral, tangent, spiral, curve, spiral, tangent). The curve is necessary to fit a pair of 400-meter island platforms (long enough to berth a double-length high-speed train) without bulldozing too much real estate.

Here is how this all fits (admittedly just barely) in downtown Redwood City:

The sacrificial victim is the Sequoia Station shopping center and associated surface parking crater, which can be redeveloped as part of the station complex with direct access from El Camino Real. Access for high-rise fire apparatus around the viaduct structure might also be a concern for the new condo buildings to the south, although this can be mitigated.

The station includes two pocket sidings to turn commuter trains. The siding south of the station can turn Caltrain locals at Redwood City, while the siding north of the station can turn Dumbarton service. Each siding is sized to store an eight-car EMU. Track center spacing is 15 feet throughout, and platform setback is 6 feet from track center. All viaducts are made from low-profile U-shaped sections that minimize the required height of the tracks and also double as sound walls, reducing the noise of up to 30 trains that would serve the station every peak hour.

Redwood City's slogan, "climate best by government test" would also become "transfer best" with timed, well-coordinated transfers to a variety of destinations. The impending start of designs for grade separations in Redwood City needs to factor in this future, and the city ought to think big.

Thoughts on Palo Alto

There is a vigorous discussion of grade separations now underway in Palo Alto. It misses several important points:

1) Grade Separation is not one project. Trying to come up with a single, grand unifying grade separation scheme for the entire rail corridor through Palo Alto is to over-constrain the problem and to limit the range of feasible solutions. The wide geographical spacing of the four remaining grade crossings in Palo Alto leads naturally and logically to three separate and independent projects: Alma, Churchill, and Meadow/Charleston. These three projects can be and should be completely decoupled from an engineering perspective, if not from a political perspective. The underlying geometry of Palo Alto does not lend itself to a single project.

2) Creating new cross-corridor access is not grade separation. While it is understandable that the city desires to knit together neighborhoods on opposite sides of the track by creating new places ("trench caps") where people can access the other side of the corridor, this is not grade separation and should not be funded by scarce grade separation or transportation dollars. It can't be said that the city was actively divided by the rail corridor, since the rail corridor was in place decades before Palo Alto grew into a city. While everyone agrees that new cross-corridor access would improve Palo Alto, the distinction of scope between grade separation of existing crossings (today's network topology) and new cross-corridor access (tomorrow's network topology, a nice-to-have) should remain crystal clear. Muddling the project scope will muddle the discussion of funding.

3) Split-grade solutions should be studied with due diligence. When the city commissioned a grade separation study from engineering firm Mott Macdonald, the council deliberately excluded from consideration any designs where rails or roads might rise above existing grade. From the outset, this eliminated the standard solution that every other peninsula city has adopted: San Bruno, Burlingame, San Mateo, Belmont, San Carlos, Menlo Park and Sunnyvale either already have or are planning split grade separations, where the rails are raised a bit and the streets are lowered a bit. Turning a blind eye to split grade solutions, however controversial they may be, casts doubt on the entire decision making process. Without due diligence in studying a full range of grade separation solutions, the politics of assembling the necessary funding will become unnecessarily complicated.

4) Funding matters. The most expensive options are the most popular because the cost isn't yet borne by anyone. Everything is paid for with OPM or Other People's Money. If you went to a restaurant with OPM, of course you would select the Filet Mignon (or truffles, if you're vegetarian). A selection process that ignores funding is detached from reality. This also means teaching people about orders of magnitude: capturing ill-defined revenue from new uses of 45 acres of highly impaired land that the city doesn't own, even at Palo Alto prices, doesn't begin to pay for the astronomical expense of burying the tracks. Until funding is seriously factored into decision making, it's all just unicorns and rainbows.

5) County grade separation funding is always at risk. While 2016 Measure B set aside $700 million for grade separation projects, a 3/4 majority vote of the VTA board is all that it takes to re-program some or all of that funding "as circumstances warrant" towards BART, in the exceedingly likely event that the San Jose extension goes over budget. Spend it soon, or flush it into a giant sink hole in San Jose.

Failing to properly acknowledge these realities will likely leave Palo Alto's decision making process tied in knots as other cities move forward.

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.