12 August 2017

Freeway Lanes of Caltrain

If everyone drove instead of taking Caltrain, how many more lanes would peninsula freeways need to absorb the additional traffic?

The way to answer this question is to count how many train passengers ride past any given location, in each direction, within the span of one hour. Caltrain publishes all the information you need to do this calculation rigorously, without making any assumptions: the timetable tells you when each train passes each location, and the 2016 weekday passenger count by train tells you how many people are on board that train at that time.

Four cases are considered: morning northbound, evening northbound, morning southbound, and evening southbound. Rather than picking a fixed morning and evening hour over which to count passengers, we slide a one-hour window across the peak period until we find the peak hour at each location, during which the most passengers ride past. Caltrain operates five trains per hour per direction repeating on an hourly cadence, so we never count more than five trains in the totals.

It is an easy but tedious calculation, perfectly suited for a computer.  This is what pops out:


This graph reveals many of the features noted in ridership reports: the flow is asymmetrical with more riders traveling northbound AM / southbound PM, the Gilroy branch is dead, Stanford generates enormous ridership, etc.

Translation to Freeway Lanes

To convert the number of Caltrain passengers into freeway lanes, very few assumptions are needed, and those we need can be backed up by references.
  1. A congested freeway lane operating at 45 mph can carry 2000 passenger cars per hour, according to the Federal Highway Administration's HPMS Field Manual (Parameter values: FFS = 45 mph, BaseCap = 2150 pcphpl, PHF = 0.95, fHV = 0.98, fp = 1.0).
     
  2. The average vehicle occupancy (AVO) is 1.3 people, based on two studies of the 101 corridor in San Mateo County. This figure includes buses, van pools and corporate shuttles.
This means a single freeway lane can theoretically carry 2600 people in one hour. Note this is a very optimistic figure because slight perturbations in the flow of traffic can cause slow-downs that reduce throughput due to lower free flow speed (FFS). But we'll use this very high number to make an extremely conservative estimate of how many lanes of freeway can carry all of Caltrain's ridership.

Freeway lanes typically do not change directions to accommodate peak flows. That means we must consider northbound lanes separately from southbound lanes, with no possibility of re-allocating the lane capacity to accommodate the AM/PM flow asymmetry that is observed on Caltrain. In practice, this means we must add the northbound peak flow (AM or PM, whichever is highest) to the southbound peak flow (again the highest of AM or PM) to size the number of equivalent freeway lanes. Looking at the graph above, which shows the highest flow is northbound AM and southbound PM, we must add AM northbound and PM southbound people per hour, and divide by 2600 people per hour per freeway lane. Here is the result:


So as of 2016, plain old diesel Caltrain equals about 2.5 lanes of freeway, including both directions. If you integrate the area under this curve, you get how many lane-miles of freeway would be needed to replace Caltrain. That number is 119 lane-miles. These are very conservative lower bounds.

When you hear the argument that "millions" of people use highway 101 but only about 30,000 people use Caltrain, shut it down with facts: today Caltrain amounts to 2.5 / 8 or at least 30% of the lane capacity of highway 101 during rush hour. The reply might be that not all those people would end up on 101, but with an average trip length of 23 miles, which driver wouldn't use a freeway?

Future Capacity Implications

Caltrain capacity is set to increase considerably, first by ~30% with the initial electrification and modernization project, and by ~60% once the system is running at 6 trains per hour with 8 cars each. (If you don't count standees, those figures are ~10% and ~25%, but why would you not count standees?) A 60% capacity increase is equivalent to one and a half lanes added to the entire length of highway 101 from San Jose to San Francisco.

It doesn't have to stop there: more trains per hour and longer trains are possible, because EMU trains scale up in a way that diesel can't. A future Caltrain capacity increase to about 10,000 passengers per peak hour per direction (about triple today's throughput) isn't out of the question, does not require adding tracks or expanding the rail corridor, and would equate to adding 5 new freeway lanes.

In certain quarters of Silicon Valley that are enamored of Hyperloops, self-driving Teslas and Boring underground tunnels, electric Caltrain is looked down upon as a last-century technology that is about to be made obsolete. That particular outlook fails to grasp the importance of throughput or to recognize the enormous carrying capacity of modern electric rail. Self-driving Teslas and Hyperloops will achieve dismal throughput capacity as measured in passengers per hour, and no amount of whiz-bang technology will change the underlying geometry of this increasingly urban region.

The way forward is to add more freeway lanes of Caltrain.

41 comments:

  1. Compare a future Caltrain capacity of about 10,000 passengers per peak hour per direction to a freeway lane full of buses. A bus takes up about the same space as two average cars when including the gaps between vehicles. At 2000 cars per hour that's 1000 buses. To be a little conservative, say it's 900 buses. Commuter buses have about 50 seats. Note that every rider gets a seat and nobody having to stand.

    A dedicated lane for buses could move 45,000 passengers per peak hour per direction vs 10,000 for future expanded Caltrain. The amazing thing about self-driving vehicles will be how much they lower costs. Bus transit agencies spend about two thirds of their budget on labor. Meaning the cost of providing bus service can halve when buses are self driving.

    I suggest the way forward include a dedicated freeway lane for buses carrying 4.5 lanes of Caltrain.

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    1. Ten thousand people per hour isn't some sort of inherent limit of rail. BART carries more than twice that hourly ridership through the Transbay Tube to SF on one inbound track every weekday morning. Systems in Paris or Tokyo do even more (see RER A)

      As for the high cost of bus labor, that problem was solved over a century ago by coupling high-capacity vehicles together into formations known as "trains." Elon Musk is about to rediscover them in his next iteration of the Hyperloop, after he realizes its throughput is puny.

      Finally, these freeway self-driving buses can't run at 900 vehicles per hour directly into dense downtown areas.

      Good luck solving this solved technology problem!

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    2. 900 vehicles per hour all going to the same stops would be a terrible waste. Passengers would have to reach the same two dozen places. People not adjacent to the stops would have to walk, bike, take a bus, or some other vehicle to get there. It would work much better for traffic and much more conveniently for passengers if the buses went to a hundred or more separate locations. For example a half dozen in SoMa, a half dozen in FiDi, a half dozen in the Mission, etc.

      Then those buses also don't need to stop at every station. Just like Caltrains skip stops. Imagine if the train cars were independent, and all went to the busiest stops, but then individual cars skipped different stops. Passengers simply boarded the train car that would stop at their destination, resulting in faster trip times. Times made even faster by taking people to so many more destinations closer to many of their jobs or neighborhoods.

      Yes it's still more expensive, but it's more convenient, direct, reduces transfers, and has a comfortable, everybody-is-seated throughput higher than BART today in the tube (23 ten car trains per hour with a miserable crush load of 180 passengers = 41,400). When BART gets ATC and does 29 trains, only uncomfortable levels of crowding will match what a lane of buses can do. I'm not opposed to Caltrain, but there's a perfectly good, incredibly versatile right-of-way going vastly underused on every multi-lane freeway. I hope self-driving buses enable more people to see that potential.

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    3. Whether a 50 seater bus is "comfortable" may be in the eye of the beholder…

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    4. I was on the #22 bus a couple of years ago and some gals in the back were passing a 40oz. around. They were plenty comfortable.

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    5. Perhaps I was a bit harsh. Two conciliatory points:

      (1) automatic buses and cars are quite complementary to a rail backbone to provide first and/or last mile capillary transportation

      (2) anyone who invents a way to increase freeway average vehicle occupancy from 1.3 to 3 or even 8 as contemplated here deserves our collective gratitude and a Silicon Valley ton of money!

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    6. re comfort on bus vs train... a - I think you can also pass a 40 oz around in the back of the train ? b - I can read or do any kind of close work on the train, but if I try that on a bus I am nauseous within minutes c - have always loved the toot toot and clickety clack train noises d - train toilet not my fave of toilets, but would take that over a bus one any day

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    7. I tried a Bolt bus once from Seattle to Portland. It got stuck in Tacoma traffic for about an hour while a Cascade train when whizzing by. Train also offered a cafe with Ivar's clam chowder and wine on the menu. Not possible on bus. For short distances buses make great feeder tools to Seattle's Link system. But with seattle's bottleneck transpo grid transportation lanes are precious and I can't imagine using a less productive tool then the Link trains to move the masses between major points.

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    8. 1) Elon Musk has no intention to couple anything.
      2) Tesla formations are known as "convoys", not "trains".

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    9. Oh don't worry, he'll eventually discover the coupler. Maybe he'll call it the "convoy spacing bar."

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    10. Eventually, he found out that hovercraft are never going to be more than a niche application. last I heard they are reinventing things proposed back in the 50s and 60s with the maglev PRT in tubes.

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  2. On what are those 10000 passengers per hour based? 12 200-m bilevel trains?

    With moderate investments (lengthening of platforms to 300 m, more trains), the same 12 trains have a 15000 passenger capacity. Adding another 100 m to the platforms gives another 5000.

    Improve the signalling system to 24 tph capabilty, you have doubled the capacity. And 24 tph is not really technical limit, and can be handled without doubling the station tracks.

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    1. Meanwhile, it seems rather awkward that the HSR people propose to permanently limit Caltrain traffic to 6 trains per hour per direction.

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    2. The question is how many slots HSR would need. Assuming that the slots are based on a Caltrain local, a high speed train would need 2. That would give, based on the 24 tph capability, 8 tph per operator. It might be possible to squeeze in a little bit more for HSR, if two trains would follow each other immediately, using 3 slots in total.

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    3. The problem with blending the two systems over 80 km is that the differences in average speed are compounded, thus requiring more "slots" for one HSR train.

      This is one of the reasons I keep beating the drum for level boarding: dwell time pisses away capacity. Level boarding can at least mitigate the capacity constraint of blended HSR.

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    4. This is a similar situation as in the Gotthard Base Tunnel, where passenger expresses running at up to 250 km/h and freight trains running at maybe 120 km/h have to be accommodated. The passenger expresses use two slots (if not more), and the decision to run a passenger express every 30 minutes, took away 2 freight slots, which means a reduction by 25%…

      With combining S-Bahn and HSR, the problem is that it is the slower train doing the stops. If it were the other way round, fast passenger change, and very good acceleration could squeeze both train types in a same slot.

      In the situation here, you are absolutely right, that the S-Bahn train has to be as quick as possible, and that includes the dwelling time at a stop.

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    5. Clarification: The decision to run a passenger express every 30 minutes was against running two passenger expresses following each other within a few minutes, but only every hour. Note the operation patterns on the Gotthard line would accept such a scenario because of branching.

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    6. HSR trains can go as slow as the local train if they need to.

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    7. You're pointing out that HSR and Caltrain have diverging interests in the way that they prefer to allocate corridor capacity. Compromise will be hard.

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    8. Making it four tracked was going to make the chicken milk curdle and cause too many invasive weed trees to be cut down. Them OMG there were going to be MoAr trains in the beloved scenic grade crossings. A great and stunning shock that running more trains would mean ....more trains! they were offered going through all the pain all at once. They can have it in tiny pieces over the decades instead. Into a terminal anybody who spent 90 seconds looking at, could figure out would be inadequate. I'm glad I won't be around to watch it unfold.

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    9. @Max Correct: every baby bullet platform in Santa Clara County is being lengthened to 400M or enough for 2,000 seats/train (KISS need not apply).

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    10. @Roland, when and with what funding?

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  3. All of these calculations may be well and good, but any expanded capacity of Caltrain, must be accompanied with the public being willing and wnating to ride the train.

    Clem conveniently ignores and keeps touting capacity increases with use of standees. Well the FTA doesn't accept standees in its capacity calculations. Who in hell wants to have to stand for 30 minutes to 1 hour.

    Caltrain doesn't solve the needs for those who commute and still have a long way to their jobs or from their homes --- those commuters and they outnumber Caltrain commuters need freeways to achieve their commute.

    Clem, ignores the costs, which is already at $2.1 billion, will need a whole lot more funds to for more EMUs.

    Then were have the enormous cost of grade separating the whole Caltrain run -- think $6 billion or more.

    Finally who in the world expects hopeless Caltrain to really become this well oiled machine that Clem projects? Think of Caltrain not being able to solve its PTC project. Think of Caltrain as pushing onto the public a sales tax increase of $100 million per year, when their own projects say they will only need $30 - 40 millions per year for future subsidies.

    Finally, with the not passed fare, GOPASS and parking fee increase, expect to see the wonderous projections of ridership in the future to decrease drastically.

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    1. There is a proliferation of arguments here that I see as form of acknowledgement of the validity of the data presented in my post. It's not that the calculations "may be well and good"-- they are reproducible and incontrovertible. You can check them yourself if so inclined.

      On to your other points.

      Travel demand is clearly there, which is why efforts are afoot to expand 101 in San Mateo County from 8 to 10 lanes (after several years of expansion in Santa Clara County, at a cost of hundreds of millions, which resulted in zero improvement to free flow speeds after latent demand instantly absorbed new supply). It's hard to question that the public would somehow be reluctant to ride the train when every rush hour features trains filled to the rafters, standing room only, while the freeways are bumper to bumper. Making the trains swift and modern can only help. The implied notion that Caltrain is about to hit an invisible demand ceiling is ridiculous and unfounded.

      Standees are perfectly valid riders. Ask the thousands of BART sardines in the Transbay Tube, who by the way are counted by the FTA. That the agency doesn't count standees for systems that it arbitrarily classes as "commuter rail" is a specious artifact; riders are riders whether they sit or stand. Commuters always find the path of least hardship, and sometimes that does unfortunately mean standing for half an hour.

      As for Caltrain not serving every area, origin or destination, the same can be said of highway 101, highway 280, or any other piece of transportation infrastructure. It's a circulatory system with a few large arteries and numerous small capillaries. The connections in this network will only get better with the advent of automated ("self driving") road vehicles to improve first-mile/last-mile access, making the rail backbone even more attractive to commuters.

      The costs are sunk, and for all the yammering over costs we rarely hear a peep of opposition to the cost of freeway widening. The aforementioned San Mateo County freeway expansion will cost 4 to 7 million per lane-mile and occur entirely within the existing right of way. What Caltrain is now doing (metaphorically) is swapping out the foundation of their house so they can build higher; the cost is significant and the benefits won't be tangible for some time. Adding EMUs to the fleet and extending platforms as warranted to meet demand will be a much smaller expense once that foundation is laid.

      As to Caltrain's ability to successfully execute their plans, I'll say that we should all expect Caltrain to become a well-oiled machine. They should not get a free pass from you because they are an inefficient bureaucracy or whatever excuse you think they have. Everyone can and should help kick them into better shape.

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  4. Wow. Caltrain REALLY needs to ax most service south of Sunnyvale. A single track with half-hourly peak service would be way more than enough.

    Remind me again where the multi-level shit-show intergalactic station and the insane elevated HSR-only Caltrain-hating quadruple tracks are happening?

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    1. Not happening. The Ben & Ponytail show has been eliminated from further consideration.

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    2. Given how many Google Employees take Google Bus to work already, you can imagine how many more will take transit. Even if some drive, many will take Caltrain after work to go up to SF.

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  5. Ummm... take another look at the data. SJ Diridon has >1100 NB AM hourly boardings. It's clearly more of an origin than a destination station, but that should surprise nobody who has heard about SJ's job/housing imbalance.

    Speaking of the elevated HSR alignment at Diridon, please check out HSRs proposal for an at-grade alignment shown in their August CWG meeting (slide 33). It includes 5 (!) tracks through the Gardner neighborhood as well as multiple property takes and new grade separations. The elevated alignment starts to look pretty good compared to this monstrosity (which I'm guessing is the general objective).

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    1. This was meant as a reply to the Anonymous comment above. The link to the CWG meeting is http://www.hsr.ca.gov/docs/programs/statewide_rail/proj_sections/SanJose_Merced/San_Jose_CWG_PPT_080217.pdf

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    2. Yikes. Here is a direct link. Slide 33 is the key slide, although it's barely legible and the original full-resolution map does not seem to have been made available.

      The at-grade alternative is clearly being sand bagged here. Do not cross two train flows as they approach SJ from the North; keep ACE and Amtrak on the east side, and Caltrain HSR on the west side, and never the two shall conflict. Make Caltrain and HSR share platforms just like at SF Transbay. Make UPRR blend under the wire; there is no technical reason they can't do what CSX does every day, even with double stack container freight. Three tracks through Gardner, all of them electrified, are probably sufficient. UPRR may hem and haw, but money talks in Omaha. I have other thoughts that will probably be worth another post at some point. One thing is exceedingly clear: nobody is even trying to make the at-grade option work properly. Where is the City of San Jose to knock some sense into this circus?

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    3. The Slide caption implies there is a West option too, but it is not shown. My understanding is that San Jose prefers the Arial alignment to at grade if no tunnel option is possible.

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    4. Your understanding is incorrect: https://youtu.be/CBJTPqsxjGQ

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    5. @Roland Thanks for the video link. I'm not sure where in the 2.5 hour session you are referring to, but this seems like pretty much what I expected from the slides. It was mostly explaining to the CWG why the tunnel options they prefer are not going to happen. SJ City's main input is spending some money on tunnel consultants who will most likely agree with this conclusion. SJ must know this as already as they proposed the aerial alignment themselves back in 2010.
      The HSR people were basically saying that you either need to do the aerial option or work around the operational limitations of the 3-track blended at-grade solution (including the wildest dreams of Amtrak and ACE), which I guess means doing things like what @Clem proposes. If you want the operational capacity of the aerial option at-grade, you need more tracks and that results in massive impacts. (The west option looks even worse than the east one from a brief glimpse...) Based on the gentleman at 1:57, this got the reaction they expected from Gardner residents. HSR say they are not going forward with these 5-track at-grade alignments.

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  6. Sorry Clem but do you know what has happened with the cahsr blog? (R Cruickshank)

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    1. @Gary, how should Clem know ... why don't you ask Robert Cruickshank ?

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    2. Robert Cruickshank's email is cruickshank <at-sign> gmail.com

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    3. I don't see an email address for RC - all I see is a Facebook page that hasn't been posted on since 2016. If you're same Reality Check as the one on the CAHSR Blog, do you know? For me, at any rate, it stopped being active in May.

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  7. While I haven't bothered to ask him ... I think anyone that followed it can make reasonable good guesses as to why Robert put his CAHSR blog out of its misery. But if you get a response from Robert that's surprising, be sure to let us know :-)

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  8. While there are battles to be fought, I just don't have as many objections to the aerial approach to SJ as I do to other areas. Expanding beyond 2 tracks through this neighborhood is going to be met with as much pleasure as with PAMPA area. However, unlike the PAMPA area where there aren't viable alternatives, the aerial alternative runs over highway, so has less impacts, has roughly same speed/distance since it's essentially doing same S curve as current alignment, and given that CHSR's private ROW begins South of Diridon, it's not negatively impacting Caltrain.

    The cost of that segment will roughly equal the cost of expanding that section to 4-tracks after you factor in years of lawsuits and delays.

    To me, the only downside is that it requires greater expense north of SJ to bring the tracks up to that level.

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