You cannot afford to ride Boring Company tunnels, either

Last time I brought up the Boring Company, I discussed some of the issues with the silver bullet thinking behind the project, similar projects that failed in the past, and the effect that the project could have on its urban environment if it were built. Since then the plans for the first phase of development have been revealed to the public. Today, I’d like to delve into the technical reasons why the Boring Company can’t solve LA’s traffic woes, and what the service is likely to look like in the future assuming it is built as advertised.

The tunnels have low capacity

We can start by estimating the ideal capacity of a single tunnel. There are two things we need to know to figure this out—the sled speed and a safe stopping distance that should be kept between adjacent sleds. Stopping distance is dependent on the sled speed and the g-force that riders are willing to sit through. (Normal stopping distances as on a freeway also need to include human reaction time, which we presumably don’t have to worry about here.) Mr. Musk claims that the sleds have a top speed of 120 mph, and for the following discussion I’ll assume that the sleds will stop by decelerating at a constant 1 g. This means that our sleds could go from top speed to complete stop in a bit under 5.5 seconds, and our stopping distance is 480 feet.

For now, we will also ignore how cars enter and leave the tunnel. We are just looking at maximum possible capacity given an operating speed of 120 mph and without having to make passengers uncomfortable (by potentially stopping very quickly) or unsafe (by not leaving the full stopping distance between adjacent sleds). 120 mph is 176 feet per second, which means that with a distance of 480 feet between sleds, we can put one sled through the tunnel every 2.73 seconds, for a total of 1,320 cars per hour per tunnel. Compare this against realistic estimates of freeway capacity: Caltrans estimates that one lane on a multi-lane freeway has a capacity of around 2,300 cars per hour.

There are other complications we haven’t considered yet in order to make the math easier. Our model basically assumed cars appear at one end of the tunnel, go straight, and disappear at the other end. In real-world use, cars will need to be loaded into the tunnels and taken out of them, and these processes are likely to take longer than 2.7 seconds. It’s also not clear from the plans whether cars all enter and leave at the designated “stops” or whether there are frequent exits and on-ramps, as in current freeway design. If it’s the latter, we are going to have big issues with merging and this is going to reduce the sled speed from the promised 120 mph. If it’s the former, then not only this is not the panacea for traffic that Mr. Musk claims it is, but it’s also going to have all of these problems anyway when the system expands beyond the two “stations” planned in the first phase. The supply and distribution of sleds will also be difficult; bikesharing companies are already running into similar issues today and need to do out-of-band redistribution of bikes to ensure that people won’t arrive at a dock and find that there is no bike to take, or that sleds have somewhere to go when they arrive. This means the company will probably have to deadhead sleds around, which reduces the capacity even further.

Mr. Musk claims that we can fix this problem simply by building more and more tunnels. One mile of six-lane urban freeway costs around $11 million according to ARTBA. To get similar capacity out of Boring Company tunnels, we would need to build at least 11 tunnels. The 405 which Mr. Musk wants to build under can have as many as 12 lanes. Even if he achieves his goal of reducing costs by a factor of 10 and boring tunnels at $100 million per mile per tunnel, that’s still over $2 billion for one mile of equivalent capacity. (I estimate that the proposed network covers about 60 miles, putting the cost in the hundreds of billions even in the best case.) Given that the 405 is already way over capacity, we are going to be making absolutely massive capital expenditures for little ability to move people around. But is Mr. Musk actually trying to solve issues of mobility?

Users pay for entry either in money or in time

High-speed, low-capacity transportation isn’t a new idea for Musk as he has proposed essentially the same thing with Hyperloop. This technical discussion of capacity issues on Hyperloop was an inspiration for the post you’re reading right now. If we open up a new system which allows you to get somewhere twice as fast as the current system, we should expect that lots of people will want to use it. Given the state of LA’s freeways and in particular the 405 as stated above, I think it’s safe to assume this demand will quickly surpass the low capacity of the tunnels.

Freeways already have capacity problems and work around them in one of two ways—either by charging tolls, or by forcing people to wait to get on and sit in traffic when they have managed to do so. In other words, given that the freeway has limited supply and high demand, we can either raise the cost or “ration it” and pay in time instead. If the 120 mph ride would save people an hour, they’ll be willing to wait almost that long if the price was low. Given that Mr. Musk first proposed this idea because he was frustrated about sitting in traffic, he would probably bristle at his company gaining a reputation for simply exchanging one type of waiting for another. So, we should expect the price of entry to a Boring Company tunnel to be very high.

This might be a great business plan, but it is a very bad way to move around large numbers of Angelenos.

Personal vehicle use and high capacity are at odds

The ultimate issue here is, of course, that we are still trying to move people around in cars. At 1.3 people per vehicle, a freeway lane moves about 3,000 people per hour. Boring Company tunnels will move around 1,700 people per hour in absolutely ideal conditions.

Our other option is obviously real high-capacity transit, which LA Metro is currently studying along the corridor that Mr. Musk wants to build his tunnels under. Metro is considering both light and heavy rail for this corridor. The Kinkisharyo P3010 has 68 seats and Metro assumes a load ratio of 1.3, so they would expect a typical 3-car train to hold 265 people. During commute hours, the number of people per car can be higher. At a full load, we might expect 150 people per car; at crush load, perhaps 200. Since this corridor is so heavily traveled, we can assume they would run on headways of at most 5 minutes, bringing us to 12 trains per hour. This is 5,400 people per hour at full load and 7,200 at crush load. Without building any extra tunnels or track, we can trivially decrease headways to 2 minutes, putting us over 13,000 people per hour. If Metro goes with heavy rail, train length goes up by a factor of three, and capacity goes up by at least that much.

Mr. Musk thinks that the big issue with grade-separated transportation is the cost of building tunnels. Even if he achieves the cost savings he promises, we would still get less capacity per dollar than we can now. Ironically, in (correctly) identifying that our current capital projects waste a lot of money, he has managed to find a way to make them even worse.

The tunnels combine the worst features of freeways and railways

We’ve already gone over how these tunnels are quickly going to run into capacity constraints, like freeways. They also contain vehicles that move on rails, and incur all of the maintenance issues that come along with that. The most obvious is rail maintenance; they will probably have to shut down the tunnels every night until there are several of them, at which point they might be able to stay open with reduced capacity.

Additionally, the Boring Company will have to design freeway structures on rails, such as interchanges. If they don’t want sleds to stop, they are going to have to build interchanges at every junction. This is much more complicated if they plan to have multiple “lanes” because they will either have to create flyovers connecting each “lane” to one in the perpendicular direction, or will have to allow sleds to move between “lanes,” creating all of the problems freeways currently have with people merging into the right lane to take an exit. This has further implications for capacity and speed, especially since sleds can’t merge at arbitrary points. They have to wait for a switch, just like a train.

They will also have to build station cavern equivalents to accommodate all of the cars moving between the surface roads and the tunnel network. Because the headways are so short and the dwell times of the sleds are comparatively long, these station caverns will have to be many times the size and complexity of current rapid transit station caverns. Commuter rail terminals for large networks already suffer from this issue, as showcased by Penn Station for the Long Island Rail Road. There is no through-running and trains dwell for a long time, so they come in faster than they leave during morning peak hours. As a result, Penn Station has to have an incredible number of tracks to handle the load. Additionally, Musk wants to build tunnels layers deep when he needs to increase capacity. Station caverns are perhaps the most expensive and time-consuming components of building subway lines right now, and they only get more expensive and complicated to build when you make them bigger and deeper.

We shouldn’t expect good ideas from someone who owns a car company

If Mr. Musk truly thought these tunnels were a cost-effective and sustainable way to get people around LA, it would show that he hasn’t done his due diligence. (Perhaps he’s too busy getting into Twitter fights with people who actually study and work on transportation issues.) But while I personally don’t consider most of Mr. Musk’s ideas that interesting or forward-thinking, I have a hard time believing that he’s stupid, and he does have good business sense. It should be clear that the aim of the Boring Company is not solving urban transportation problems. It is a member of the car industry digging its heels in and trying to stay relevant in a world where people are realizing cars can’t provide us with the transportation we need.

Mr. Musk owns Tesla Motors, which manufactures electric cars. Tesla’s claim to fame is that the cars have a good deal of range, and a lot of people like them. To ensure the success of Tesla, Mr. Musk has to ensure that the car industry continues to survive—it’s now well known that he has a personal hatred of public transit, but he also has a powerful financial incentive to stem the tide of transit development in places like LA. This is also why he is investing so heavily in self-driving technology. I’ve talked about this in a prior post: self-driving cars would not help move more people around, either, but it would make people willing to tolerate much longer commutes. The owner of a car company is trying to come up with “new” ideas for transportation, and it should come as no surprise that he thinks the biggest problem is that he’s not selling enough cars.

Consider that one of the ways Musk plans to reduce drilling costs is by reducing the diameter of tunnels to 14 feet. This makes them unusable for mass transit vehicles, which are almost that tall on their own. If we try to use the tunnel as a busway, we will probably need around 11 feet of flat “lane” for the bus to drive over. The bus itself is also at least 8 feet wide. A reasonable estimate of tunnel wall thickness would be 8 inches, and so this works out to a usable clearance of at most 8 feet, which is not enough for a bus. Narrowing the lane to 10 feet provides an extra 8 inches of clearance, but this is still not enough, and trolleybuses are right out. The aforementioned Kinkisharyo P3010 cars stand 12.5 feet tall and along with the tunnel walls, floor, track, and overhead wires, they will easily exceed the 14 foot diameter of the tunnel. (For comparison, Central Subway tunnels meant for similar light rail vehicles are 20 feet in diameter). Breda A650 heavy rail cars stand at 12 feet and will not be able to fit, either. These tunnels will only ever be useful for cars.

In the past, private transportation infrastructure could be acquired and run by the municipal government, increasing the availability of affordable rapid transit. Many New York City Subway lines were at one time run by the private Interborough Rapid Transit (IRT) Company and Brooklyn-Manhattan Transit (BMT) Corporation. Mr. Musk has effectively prevented the same thing from happening to the infrastructure he wants to build, ensuring that it won’t have the opportunity to become widely useful.

The Boring Company claims it will be able to provide cheap, fast, and convenient transportation for everyone. This isn’t possible given its technical details, but it was never the point, either. Musk is in this for the money. He wants people to continue to buy his cars, and to pay lots of money to ride around in his tunnels. The obvious consequence is that we will have a two-tiered transportation network where the vast majority of Angelenos won’t benefit, but a small group of very wealthy folks will be able to move around at will.

If you are not one of these wealthy people, you will not see any improvement in mobility if the Boring Company builds out their proposal. Elon will make lots of money while the streets fill up with even more cars. We risk keeping LA from getting the quality mass transit system it desperately needs if we let him distract us any more.


How bad is the last mile problem in San Francisco?

The “last mile problem” is often invoked by Uber and Lyft to justify their attempts to cannibalize public transit ridership. From this article in the Examiner:

Both Lyft and Uber offer bus-like services for their vehicles, Lyft Shuttle and Uber Express POOL. The Uber Express POOL service is set to launch in six more cities nationwide Wednesday, though it has operated in San Francisco since November 2017.

Kate Toran, head of taxi services at SFMTA, who also helped craft the rules around private mass transit, said Lyft Shuttle is regulated by the California Public Utilities Commission, not the SFMTA, because it seats so few passengers in each vehicle.

While SFMTA officials have expressed concern about Chariot potentially competing with Muni, Uber staff argued Tuesday that the company’s new carpool service also may address routes public transit may not serve well.

In a Tuesday briefing with reporters, Ethan Stock, head of Product at Uber, said he viewed Uber’s Express POOL service as a solution to the “last mile problem,” where public transit doesn’t bring people to their destination doorstep.

“One of my favorite examples is my own commute,” he said. “I would love to take Caltrain up the Peninsula and have a seamless Caltrain ride to the Uber office (in San Francisco).”

Yet, he said, “the amount of time and frustration” he has trying to get from Caltrain to his offices at Uber on Market Street is a barrier to using public transit.

“I think this is an example of a gap in the public transit system I think Uber is in a position to fill,” he said. “Public transit works really well on core, high volume routes, but in the diversity of moving all over the city, it doesn’t.”

I’d like to answer both the specific and abstract arguments made by Mr. Stock. I can’t tell from his statements alone whether or not he takes Uber to his office from his house or from the Caltrain station at 4th & King. In the former case, it’s not feasible for everyone to have a one-seat ride from far away to their destination. If you want to know what happens when we try to give everyone a one-seat ride, you need look no further than awful 101 traffic. Either way, since he brings up the “last mile problem” I assume he’s proposing Uber as a solution for the latter.

The Uber office is at 11th & Market, so getting there from the Caltrain station is a direct ride on the 47. This is an incredibly frequent bus—one of the most frequent in the entire system. Ridership on this line is over 10,000 per weekday, and it shares a significant portion of its length with the 49, which has much higher ridership. By all means, this is the kind of “core, high volume” route that Mr. Stock thinks transit works well on. It picks him up where he gets off the train and delivers him to a point about a minute’s walk from his destination. More generally and as I talked about in my first post, the frequent grid covers San Francisco with these high-ridership routes, and this is especially true downtown. So why does Mr. Stock consider this frustrating and difficult, and what part of the last mile problem really remains unsolved?

Mr. Stock does not consider taking the bus, and the last mile problem is only bad in San Francisco if you do not take the bus. SFMTA has designed the bus network to have nice grid properties and help people within the city commute downtown, but it has also created a system with high connectivity at all of the rapid transit stops. Because rapid transit stops are so busy, it makes sense to serve them heavily with buses, so people can make many different connections more easily. Accounting for this when designing your network makes it useful for as many people as possible, even when those people are coming from far away. From Caltrain alone, we can connect directly to almost every downtown subway stop. Embarcadero is accessible by the N or T. Montgomery is along the 10 and 12. Powell can be reached by the 30 or 45. Van Ness is on the 47. Civic Center is a bit harder as the 19 is a few blocks away, but Muni runs the 83X during peak hours to bridge that gap. The 81X and 82X also provide additional commute service from Caltrain to other destinations like the Transbay Terminal. The Central Subway will make moving people to and from the Caltrain station even easier when it is completed next year.

This is still true, if not to the same absurd level, with just about every other rapid transit stop in the city. I talked with a friend who works out in the Bayview and he revealed that his company is part of the Lyft corporate program, which helps people take Lyft from nearby BART stations to the office. His office is also accessible from Glen Park BART via the 23 and 44 buses. The 44 is especially frequent during commute hours.

Further discussion centered on the fact that buses are slow. I won’t argue with this, but we can fix it, and getting people into cars is not the right way. One part of the solution could be expanding the rapid network, as I wrote in this post. (If the 44R proposed in that post existed, his office would be a 4-stop ride and short walk from Glen Park.) Another could be installation of more red lanes, which would speed up the buses we already have. For some people, taking their bikes along or using bike-sharing services might provide a reasonable solution. But we can’t ferry everyone to their jobs from busy BART or Caltrain stations via cars, even with carpooling. The more efficient your carpooling is, the slower your ride gets, and the more it approximates standard bus service. As we take more cars, everyone’s ride gets slower. And this speaks to Mr. Stock’s final assertion—it is not mass transit that performs badly when people in a city are trying to go from anywhere to everywhere, but car-based transportation such as that provided by Uber.

In places which have less useful local bus networks, the last mile problem is worse, and car service might be the best option for people once they arrive at a nearby mass transit stop. It certainly is a more sustainable practice than driving the whole way yourself. But in San Francisco, we can do better, and tens of thousands of people already use buses to get around after taking BART or Caltrain in. It might take some investment to make them more useful, but in the end everyone will have better and faster service. Uber and Lyft have again tried to position themselves as a supplement to public transit, but it looks like they are continuing to interpret “public transit” solely as rail and if they supplant bus service, we will all lose out.

Making connections with station placement

I recently read this article about some potential development near downtown San Jose, and this along with the news of development happening around Diridon Station reminded me of the BART extension that’s supposed to come to San Jose in the mid-2020s. The San Jose subway has already been watered down from the initial proposal, in that there were two stations in the downtown area that have been consolidated into one to reduce the cost. However, the location of this single downtown station has not yet been finalized.

VTA presents two options for this station, both of which can be found here. The station will sit underneath E Santa Clara, which makes sense as that’s the main thoroughfare. The west option has the station spanning Market through 3rd, and the east option 2nd through 6th. The east option seems clearly worse: the west option is much closer to the center of downtown, and will also provide a more direct connection to the northbound buses and light rail that run on 1st and 2nd Streets. The west option would bring much higher benefit to the whole network.

Map excerpt from here, with the west option in purple and the east option in yellow.

The west option also leaves more room for an infill station between the Downtown and Alum Rock stations, which we might want to reconsider if the areas east of downtown densify significantly. An infrastructure project which has so much potential impact on San Jose should leave future options open as much as it can. Why would VTA even consider the east option, if it doesn’t fit as well with the current network and land use?

It’s likely that they would make concessions like this to avoid political battles. The west option—being closer to the middle of downtown—might engender more short-term resistance from merchants, since construction can lose them foot traffic and customers. Though this is clearly worth it for them in the long-term, merchants may not believe they will survive to get the benefit. Remember that Winter Walk SF, which shows up every December on Stockton St, is a compromise made with Union Square businesses that were afraid of losing customers. Central Subway construction in the area is suspended while this is going on, which makes it take longer and cost more.

It would also sit directly underneath the light rail tracks on 1st and 2nd Streets, which means construction on the station will probably disrupt light rail service. The city can work around this by stopping trains at Convention Center Station if they’re coming from the south and Japantown Station from the north, and running a frequent bus bridge between the two. Customers won’t be happy, though! By contrast, the east option would not require digging up 1st or 2nd Streets and light rail service could continue during the construction period.

This issue is based on the current locations of switches, and with some extra track along E St John and E San Fernando they could run trains to St James and San Antonio Stations. This would mean only Santa Clara Station would go out of service, and might provide some extra flexibility for moving trains around in the future. Additionally, these stations are less than half a mile apart and both are a short walk from downtown, so it might require less capacity on the bus bridge. I’m not sure this is enough upside for VTA to invest in something that involved, but it’s worth considering.

Unfortunately, this means the easy option is the one that does not serve the needs of riders quite as well. This shouldn’t be surprising—it’s the reason we see a lot of BART in freeway medians or why rail systems tend to expand interminably into the suburbs when they would benefit more from core capacity improvements. It should serve as a reminder that if we want a transit system that works for everyone, we’re going to need to make some noise. The VTA website lists some upcoming meetings here, so if you live in the South Bay and are interested in this, you might want to check them out.

SB827, transit, and land use

I’d like to show a few pictures to kick off discussion about this bill.

These are height and bulk maps for the areas around Glen Park BART, West Portal station, Noe Valley, and the Inner Sunset. The first two have rapid transit stations. The other two are central neighborhoods at the crossroads of several important surface transit lines—for Noe, the J, 24, and 48, and it’s also close to the 14 and BART; for the Sunset, the N, 7, and 19. These are also upscale neighborhoods and the people in them do not want to include more housing, even though they have a comparatively large amount of transit infrastructure.

Let’s look at another map:


This is the area around Washington Square Park, which is the most likely location for the next subway station along the Central Subway when that is extended through North Beach. Many frequent transit lines (8, 30, 45, the PM cable car) are already present here. It, too, is in an area that has abjured density in the past.

Contrast those maps with these:

These show the areas around 16th & Mission BART, the Fillmore neighborhood between the 22 and 24 bus lines, and Chinatown, particularly around Stockton & Washington where the Central Subway will terminate for the time being.

Recently, State Sen. Scott Wiener introduced SB827 in the state legislature. It is a bill which proposes minimum height limits on parcels close to major rapid transit stations and near frequent transit corridors. It would upzone just about all of San Francisco and large swaths of other cities like Oakland, Berkeley, San Jose, Long Beach, and LA. It’s a very interesting entry into the pool of solutions for the housing crisis, and I do think that transit-oriented development is the way forward here if we want to house everyone in a sustainable manner.

Other attempts at streamlining housing construction in the past include Jerry Brown’s 2016 housing plan, which I talked about a little here. SB827 avoids some of the problems I saw with that housing plan by largely leaving local protections and programs in place; that is, it doesn’t touch demolition controls, inclusionary zoning or the like. All it does is remove requirements on floor-area ratio and parking, and install a minimum height limit. I think this is an incredibly useful tool for making the neighborhoods in the first set of pictures take on more responsibility for the housing crisis that they have in part created instead of foisting the problem onto the neighborhoods in the second set of pictures. It is a crime that Noe Valley’s segments of 24th St and Church St have 40-foot height limits, and that West Portal has height limits as low as 26 feet. Areas this accessible can be put to better use and we need tools to do that even when their communities try to close themselves off.

Housing advocates have expressed concerns about this because upzoning has ended up causing displacement in the past. I had the opportunity to chat briefly with Mr. Wiener about where he thinks this bill is headed and what he will do to reassure those groups that this bill will not cause such massive displacement and gentrification. He said that, at least in SF, demolition controls are strong enough that we shouldn’t worry about neighborhoods being covered in cranes, and the process will be more gradual. (There are ways around these laws, of course. The spate of fires in the Mission over the past few years has been attributed in part to landlord arson, an awful practice which allows these laws to be sidestepped and right-of-return to be waited out.) He did say that this could be an issue in other cities, and in order to meet those concerns he would work out adding stronger demolition controls and right-of-return laws. He also noted that he would like to see IZ requirements added to the new development if the jurisdiction does not already have them. This would ensure affordable housing is created but avoid superseding stronger local regulations as Mr. Brown’s housing plan would have done.

I had another set of concerns which I tweeted about a few weeks ago, where communities which would like to retain their exclusivity will simply ensure that they don’t improve transit to the point where they fall under the purview of this law. For example, Mountain View can’t avoid zoning for more housing around its Caltrain station and El Camino Real if SB827 passes. However, it can try to prevent VTA from increasing the frequency of bus lines that go through it so that new areas don’t fall under this increased height limit. It may take concerted organizing by transit advocates to make sure that their cities continue to provide good public services regardless of this second-order effect. This would be especially bad in Bay cities who would be promoting sprawl and car-dependence while otherwise claiming to be committed to ecological sustainability.

This bill is unlikely to pass in its current state, and Mr. Wiener does have some ideas for how to mitigate its impact on communities. But I think the bill is a good starting point because it acknowledges the link between transit and land use. This bill does not provide any immediate and direct assistance to transit, but it does ensure that in the long term there will be more people taking transit and committed to getting it the resources it needs. As always, increases in transit ridership get agencies to improve service, which in turn makes the system better for everyone and itself increases ridership. Understanding this interaction is key to creating a Bay Area where everyone can live and get around in the coming decades.