Capacity 101

Another sidebar to an upcoming post on Sepulveda Pass (soon, I promise!).

Revised based on some input from Paul Druce (@ReasonRail) and Alon Levy (@alon_levy).

You often hear opponents of rail transit like Randal O’Toole making preposterous claims about the capacity of bus lanes, like saying they can move over 100,000 passengers (pax) per hour. So here’s a short reference guide to the capacity of different types of infrastructure. We’re going to look at one lane or track in one direction.

Freeway lane (passenger cars): the capacity of a freeway lane is about 2,400 passenger cars per lane per hour (pcplph). Assuming an occupancy of 1.5 people per vehicle, that’s 3,600 pax/hr. If you assume that the cars are full, with 4 people per vehicle, and that driverless cars will allow headways of 1 second, that’s 3,600 pcplph and 14,400 pax/hr. As Alon points out below, a realistic occupancy for commuting is about 1.2 people per vehicle, or 2,880 pax/hr. I’m being a little generous with 2,400 pcplph too, the point being that even with generous assumptions, bus and rail have higher capacity.

Exclusive guideway (bus): a 60-foot articulated bus has a standing load of about 90 people and a crush load of about 120 people. If you assume one minute headways, that’s 5,400 pax/hr standing load and 7,200 pax/hr crush load. If you assume 20 second headways (or maybe more realistically, a three bus platoon every 1 minute) that’s 16,200 pax/hr standing load and 21,600 pax/hr crush load. This is a pretty aggressive assumption for bus operations, and labor costs would be high, but it might be doable with an exclusive ROW and good dispatching.

Exclusive guideway (light rail transit – LRT): LACMTA’s design criteria specify a full load of 164 people and a crush load of 218 people for a light rail vehicle. A reasonable assumption for minimum headway on LRT is about 2 minutes, or 30 trains per hour (tph). Metro specifies a design headway of 100 seconds and an operational headway of 2.5 minutes. With CBTC, 2 minute headways are easily achievable. For three-car trains, like LACMTA runs, that’s 14,760 pax/hr full load and 19,620 pax/hr crush load. Go with four-car trains, and that bumps you up to 19,680 pax/hr full load and 26,160 pax/hr crush load. If you could drive headways down to 90 seconds (about what the slightly dysfunctional MBTA Green Line runs), you could get 40 tph for 26,240 pax/hr full load and 34,880 pax/hr crush load.

Exclusive guideway (heavy rail – metro): LACMTA’s design criteria specify a full load of 180 people and a crush load of 301 people for a heavy rail vehicle. Headway assumptions are the same as for LRT. For six-car trains at two minute headways, that’s 32,400 pax/hr full load and 54,180 pax/hr crush load. For a ten-car train at two minute headways, 54,000 pax/hr full load and 90,300 pax/hr crush load. Get it down to 1.5 minute headways and it’s 72,000 pax/hr full load and 120,400 pax/hr crush load.

Here’s a summary table.

Note that even at this level, we’re not playing fair between rail, bus, and auto. Rail capacity is effectively limited by the signaling system and other regulations like NFPA 130. Bus and passenger car capacity is limited by station capacity. Berthing a train every two minutes is a breeze. Berthing a bus every 15-20 seconds is very difficult, even with long platforms. Berthing a passenger car every 1.0-1.5 seconds is impossible.

So how do people like O’Toole get outlandish capacities like 110,000 pax/hr for bus, while claiming rail has capacity below 10,000 pax/hr? Easy, posit a bus system that doesn’t actually work, and cleverly sandbag rail.

On the bus side, O’Toole assumes a capacity of 1,100 buses per hour or about one every 3 seconds. That works great as long as no one ever has to stop. You could only operate a bus lane at that volume if it was just a trunk that many bus routes used between their origins and destinations, much the same as how cars use a freeway. Think about it: if you were running 1,100 buses per hour on the 405 and 1,110 buses per hour on the 10, you could never hope to have transfers between the lines. You couldn’t operate transit lines, only point to point services, or lines with no stops or transfers between them on the trunk.

On the rail side, O’Toole assumes 3 minute headways, versus our 2 minute headways. What’s a minute among friends? Well, going from 3 minutes to 2 minutes increases capacity by 50%. If you run with CBTC and get 1.5 minute headways, that’s twice as much capacity as O’Toole calculates. In other words, when headways are low, small differences in headway make a big difference in capacity.

At high passenger volumes, rail is still the best option, offering lower operating costs and better reliability. It’s easier to run trains at 2 minute headways than buses every 15 seconds. For lower passenger volumes, bus is often fine, but remember that, as Jarrett Walker says, the most important things is the quality of the ROW. Few cities need to move as many people as the Lexington Av subway in New York. Start with a high quality ROW, then pick the mode that’s the best combination of cost effectiveness, compatibility with existing systems, and accommodation for future growth.

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Municipal Consolidation

Municipal consolidation, or regionalism, frequently comes up in discussions of cities and their relationship with suburbs. This is especially true in places where there is a stark racial and/or economic wealth divide between the city and its suburbs, with Detroit being the classic example. Recently, with the protests in Ferguson, MO in response to police gunning down an unarmed black teenager, the New York Times published an op-ed calling for municipal consolidation in St Louis County.

Consolidation can offer many benefits for urban policy, but I don’t know if it would help the situation in Ferguson, because policy always has technical and political aspects.

Technicalities

From a technical perspective, we should just organize government at the most efficient level for the service to be provided. For example, a flood control district would logically be set up with political boundaries corresponding to the limits of the drainage basin. An irrigation district would logically be set up to govern the territory to be irrigated with a certain allotment of water. A bus service district would logically be set up to serve the denser part of a metro region.

Institutions like this exist, if imperfectly. The Imperial Irrigation District gets a fixed amount of water every year, and they manage allocations within the entire Imperial Valley. Each county in southern California is a flood control district; this means that they have to work together with drainages that cross county lines like the Santa Ana River, but it seems to work pretty well. For example, the Seven Oaks Dam is in San Bernardino County, but Orange County funded most of the local share, because it’s downstream and stands to gain from controlling floods.

In California, many cities contract out some of their city services. Maywood, for example, contracts out everything – police and fire to the county sheriff and county fire department, ambulance service to a private contractor, and schools as part of the LA Unified School District (LAUSD). Other cities contract out just a few things. Bell uses county fire and LAUSD, but maintains its own police force. Service districts often don’t follow city boundaries, as is the case with LA County’s Sanitation Districts. And for some of its sanitation districts, like District 4 (Beverly Hills), the county uses the City of LA for wastewater treatment. This setup lets cities and county entities arrange things however makes sense, without regard for city boundaries.

(Really, the only reasons I see to have a city in California are (1) local control over land use and (2) it provides a way for rich school districts to avoid having to contribute funding to poor school districts. Both of these things result in undesirable outcomes, so land use and school funding should probably be organized at a higher level of government, but that’s an issue for another time.)

With something like bus service, you can sort of feel out the right scale. For example, LA Metro provides bus services throughout much of LA County, but on the Westside, Culver City and Santa Monica operate their own bus services. As a result, services on the Westside aren’t as efficient as they could be. It makes no sense for there to be no continuous service on Bundy/Centinela, Westwood/Overland, and Jefferson. Meanwhile, Culver City is responsible for running the north-south service on Sepulveda, despite the majority of the route being in Los Angeles. Likewise, Santa Monica runs the north-south service on Lincoln all the way to the airport, and Big Blue Bus Route 12 never even comes close to entering the city. Big Blue Bus still doesn’t have real-time data, and while you can transfer from Metro buses for free, you can’t transfer from Culver City buses.

This outcome is not because the folks at Metro, Culver CityBus, and Big Blue Bus don’t try to provide quality transit services – they do! The issue is that they work under a structure that puts too much emphasis at the local scale, at the expense of the regional scale.

On the other hand, there’s no benefit to going to the next level up and integrating LA Metro bus services with, say, Bakersfield. There’s no need for the state to get involved in local bus service; in fact, you could argue there’s no real need for the local bus agency to get involved at the regional rail level other than to coordinate schedules. For example, Metrolink is operated by a joint powers agency that receives funding and planning input from all of the counties it serves; that separation insulates local bus service provided by the county. San Bernardino County can extend commuter rail to downtown SB, and Riverside County can extend service to Perris, but LA County bus riders won’t be on the hook for issues with those projects.

When one transportation agency’s scope extends beyond the logical boundaries, you often end up with questionable planning. For example, the MBTA operates local bus, express bus, rail transit, and commuter rail services in Boston. The political power of the suburbs has resulted in major expansions to commuter rail over the last couple decades, while rapid transit projects in the core have languished.

Another possible benefit of consolidation is that larger political entities draw more media scrutiny. Everyone knows the president, and most people know their federal representatives. If you’re reading this, you probably know the mayor of Los Angeles, and you might even know the CEO of LA Metro. However, unless you live in Culver City, you probably don’t know the mayor, let alone any city councilors or the people in charge of Culver CityBus. I live four blocks from Culver City, and I don’t know any of them! While media attention doesn’t guarantee a lack of corruption, it at least increases the odds that someone is trying to investigate it.

Political Realities

None of this really matters, though, if the people running the agencies are acting in bad faith.

It’s no coincidence that things like sanitation districts and flood control districts are the best examples of effectively working optimized service areas. Even if you really hate black people, it’s hard discriminate in the provision of sewer services or flood control at a fine enough scale or in a way that doesn’t impact the entire city (though obviously, New Orleans managed to do so in a blunt way with flood control, and even in the case of sewers, low-income and minority communities can face discrimination at the neighborhood level). You can’t deny sewer service to one house without causing problems for the surrounding houses. The Seven Oaks Dam is going to protect everyone in Orange County from floods, no matter what race.

However, for many services, the potential to discriminate exists within the agency’s service area. For example, a public school in a rich neighborhood and a public school in a poor neighborhood might be in the same school district, but the rich school will often systematically get better teachers, more resources, etc. Consolidation does not ensure fair distribution of resources.

In fact, in the context of discrimination, regional consolidation can make things worse, even if it makes technical sense. For years, urbanists bemoaned the lack of a regional transit agency in Detroit. The feds finally forced the issue, and in late 2012, the state created such an agency. The Southeast Michigan Council of Governments (SEMCOG) was charged with administration during the transition, and promptly used its power to reduce Detroit’s transit funding by 22%. When the problem is a desire to avoid treating some people fairly, technical solutions are helpless. There are no apolitical technical policies.

Police services are effectively administered at two levels: the neighborhood level and the individual level. At the neighborhood level, there is the relationship between the police force, the community, and the city at large – the resources provided to the police and the community, how they see each other, and so on. At the individual level, there is the way that individuals on the police force and individuals in the community interact every time they encounter each other. There’s no level of municipal consolidation that changes those interactions. Small city police forces, like Ferguson, end up with the same problems as large city police forces, like NYPD and LAPD. In other words, there’s no technical solution that ends up with Mike Brown not getting shot.

LACMTA Rail Ridership Update – July 2014

Another three months have passed, so it’s time for another look at LACMTA rail ridership. Here’s the last three years of raw data, and the rolling 12-month average for weekday boardings.

For weekday ridership, Blue Line ridership picked up a little from lows earlier this year, but the Green Line slipped a little. The Gold Line more or less held steady.

After a couple years of solid ridership gains, the Red Line has dropped off quite a bit in 2014. This might be due to the fare gate locking program resulting in fewer scofflaw riders.

Weekend ridership largely reflected the same trends as weekday ridership, with the exception of the Gold Line, which has seen considerable weekend ridership growth over the last 9 months or so. This may be due to the more frequent weekend service that Metro started running in 2013.

The star is the Expo Line again. After leveling off in the second half of 2013, weekday Expo Line ridership resumed its climb in the first half of 2014. In terms of boardings per route mile, the Expo Line, in its third year of operations, is now at about 90% of the utilization of the Blue Line – 3,603 boardings per mile for Expo, and 3,978 for Blue. The Expo Line achieves greater boardings per mile than any other modern LRT system in the country, and hit that level of ridership in less than year.

It seems possible that when Expo Phase 2 opens, the Expo Line will become LA’s most productive LRT line by boardings per mile. And of course, Regional Connector is only going to strengthen the LRT network’s appeal.

Driverless Cars and Driverless Trains

Updated with a note on platooning and some input from R Winston Kappesser (@ronaldkappesser).

There was some back and forth on Twitter today on the potential of driverless cars and their impact on rail infrastructure like transit and high speed rail. In that context, here’s a civil engineering perspective on the technological issues and potential impacts.

Stuck to You Like Rubber on Asphalt, or Steel on Steel, or Something

First, we have to understand the technological differences between rubber-tired vehicles and steel-wheeled ones. That starts where the rubber hits the road or where the steel hits the steel.

When it comes to transportation, friction is both our friend and our enemy. We need some friction; otherwise, when you hit the gas your tires would just spin in place, or your rail wheels would just do something like this. Friction between the rubber tires and the road’s asphalt or concrete surface is what keeps cars and buses from flying off the road at corners. It’s what turns the tractive effort of a big honkin’ locomotive into forward motion.

On the other hand, too much friction wears out your car’s tires and makes your car run less efficiently. For trains, friction management is a critical part of track and vehicle maintenance. If there’s too much friction, the rails and wheels will wear out faster, and the train will use more fuel, increasing maintenance and operating costs. Friction management is so important for railroads that locomotives are equipped with sanders, so that the engineer can drop sand on the rails to increase friction on upgrades, while sharp curves are equipped with greasers to reduce friction between the wheels and rails. There’s an entire sub-industry built around friction management.

In general, the coefficient of rolling resistance between rubber and asphalt is about an order of magnitude larger than that between steel and steel. This means there’s proportionally more rolling resistance between your car and the road than there is between an Expo Line train and the rails. The very low rolling resistance on railroads is part of why trains are so much more efficient at long-haul freight than trucks. The coefficient of friction is also lower for steel on steel than rubber on asphalt.

Can’t Stop, Won’t Stop

That efficiency comes with a cost, though, in braking performance. Trains can’t brake as fast as rubber-tired vehicles. How much worse? For a 70 mph design speed, Caltrans Highway Design Manual requires a stopping sight distance of 750 feet. For a 70 mph design speed in territory with cab signals, the standards used by Amtrak and many commuter railroads require a safe braking distance of 4,942 feet. For high-speed trains, the stopping distances for purposes of rail signal design can be in excess of 2 miles.

(Note: some vehicles, notably LRT vehicles and some high-speed trains, have electromagnetic track brakes that use electromagnets to “grab” the track, allowing the vehicle to stop much more quickly. These brakes are used for emergency only; safe braking distances for railroad signal design are calculated assuming no track brake is used.)

The other major difference between rubber-tired vehicles and steel-wheeled ones in this regard is the ability to steer. A person operating a rubber-tired vehicle has the ability to take evasive action to steer the vehicle away from a hazard, while a train engineer is obviously helpless to do anything other than brake.

Design Evolutions

These technological realities have resulted in a different evolutions of civil engineering design standards.

For cars, design is predicated on the driver being able to see further than the distance needed to stop the car. The design of vertical curves (changes between upgrades and downgrades) is governed by the need to ensure the ability of the driver to see over the top of the hill, or for the car’s headlights to illuminate enough of the road ahead of a sag curve. At horizontal curves, vegetation and other obstructions on side of the roadway must be cleared far enough back from the edge of the road to allow the driver to see around the curve. In a safe design for autos, the driver will always be able to see further than needed to stop the car.

In contrast, with the exception of low-speed streetcars, for trains it is simply impractical to design the track such that the engineer would always be able to see further than the distance needed to stop the train. Horizontal and vertical geometry of the track is controlled by vehicle performance and passenger comfort. Safety is ensured by the signal system providing the safe operating speed to the engineer, and in some cases enforcing that speed, based on the locations of other trains (or perhaps more accurately, based on information that sections of track ahead of the train are not already occupied by other trains).

Note the fundamental difference here. For cars, safety is based on the ability of the driver to passively gather information about conditions on the road. For trains, safety is based on active collection of information on the locations of trains, and active dissemination of instructions to trains that it is safe to proceed.

Driverless Technologies, and Others

This means that the interfaces and impacts of driverless technologies will be different for cars and trains. For cars, passive decentralized technologies (i.e. the car just gathers information, and doesn’t communicate with other cars or with a central control center) will suffice. For trains, centralized control is a necessity.

For cars, it will be a huge improvement for safety simply for driverless cars to more reliably and consistently do the things that we currently rely on human drivers to do. This will have some positive impact on practical capacity by reducing accidents. If driverless car technology allows cars to follow each other more closely than they do today, by eliminating the component of following distance related to human reaction time, that will increase road capacity.

For example, you may have already figured out that, despite the stopping sight distance being 750 feet at 70 mph, cars on a freeway flowing at 70 mph don’t actually space themselves 750 feet apart. At that rate, a freeway lane would only move about 500 cars per hour, but the actual capacity of a freeway lane is about 2,200 cars per hour. If you have a driver’s license, you may (hopefully) remember the “two second rule”, that you should leave about 2 seconds of travel distance between yourself and the car in front of you. At 70 mph, that’s a little over 200 feet – less than the stopping distance, and acceptable only because you can see further than just the car in front of you, and you have time to swerve out of the way if needed. Part of that 2 seconds is an allowance for human reaction time; if driverless cars allow that component to be eliminated, they will increase capacity.

On the other hand, safe design for trains is based on maintaining at least the stopping distance between following trains. At 70 mph, a train should never be less than 4,942 feet behind the train in front of it. In practice, the distance will always be larger due to the impact of grades and the use of fixed signal blocks. The engineer’s reaction time is portion of that stopping distance, but it’s not much. Driverless train technology has been around for decades, but the primary appeal is reducing labor costs, not increasing capacity.

If the goal is to increase capacity on rail transit, communications-based train control (CBTC) will probably offer more benefit than driverless technology, because it will eliminate the capacity waste caused by fixed signal blocks. CBTC should also allow railroads to take advantage of better braking performance available in newer rolling stock. The combination of CBTC and driverless trains would allow many transit systems to greatly improve service by increasing capacity and reducing labor costs, thereby allowing the agency to provide more service.

Lawyer Up

A big unanswered question, in my humble opinion, is the liability implications of driverless vehicle technology.

For cars, what will be the standard for safe following distance? At present, we allow drivers to follow each other at less than safe stopping distance. Will driverless cars follow the “two second rule” or will they be allowed to follow more closely? If there’s a rear-end collision, who is liable? Note that some of this must have been decided implicitly or explicitly by the people who have operational driverless cars, like Google.

For trains, at present, railroad signaling is based on the premise that the train in front of you is at a stop, and therefore you must be able to stop too. If you implement CBTC you could argue that if you know the position and the speed of the train in front of you (Heisenberg be damned), you should be allowed to follow more closely. On the other hand, if the train in front derails for some reason, it’s going to come to a stop very quickly, and any following trains that are less than the safe braking distance behind are hopelessly screwed. There’s not a consultant in business in the country today that’s going to sign off on allowing trains to follow each other at less than the safe braking distance, and I doubt any agencies would do it either.

Therefore, for trains, I really think the capacity improvements are going to come from CBTC, not driverless technology.

The Future is Uncertain

I hope this post doesn’t sound like it’s down on transit. For one thing, any improvements available to cars will be available to buses as well. And nothing is going to change the simple geometric advantages that transit enjoys in dense areas.

Predicting the future is hard. If you’re out there predicting the doom of the car every year like James Howard Kunstler or the dominance of self-driving cars in 2020 like Randal O’Toole, you’re probably going to end up looking foolish.

A conservative approach would be to continue investing in cost-effective transit improvements, including CBTC and driverless technologies, where warranted. Automated car technology should, at the very least, result in a considerable drop in the number of people killed and injured by cars, and for that alone, it should be welcomed.

Update: Platooning

A quick note on platooning, which is the idea of having driverless cars follow each other very closely, perhaps only inches apart. This would greatly increase road capacity, but it would absolutely require vehicle to vehicle, and perhaps vehicle to central control, communication, as opposed to passive information collection systems currently being used by the likes of Google. I think that getting such a system operate reliably and safely will be more difficult in practice than many people expect. I don’t think we’ll be seeing it any time soon.

Sepulveda Pass Transit, Prelude to Part 3: Should Cars Be Part of a Tunnel Through the Pass?

The next installment of Sepulveda Pass & LAX Transit is going to look at the pass itself. In the opening post to the series, I dismissed the idea of tunnel lanes for cars offhand, as impractical due to lower capacity and increased costs for things like ventilation.

I wanted to give justifiable reasons for leaving cars out of the mix in the post detailing the section through the pass. In doing research on freeway tunnels, it became apparent that this task would include so much material that it would detract from the structure and flow of the post on the pass itself. That post is intended to focus on tradeoffs between bus and rail, and alignment alternatives. So, I decided to break out the detailed look at highway tunnels as an appetizer.

Context for a Sepulveda Pass Freeway Tunnel

A tunnel following the alignment of the 405 from Wilshire to the 101 would be almost 8 miles long, making it the 10^th longest roadway tunnel in the world, though four longer tunnels are currently under construction.

The rarified company for such a tunnel consists entirely of Alps tunnels, Norwegian single-tube two-lane tunnels, and Chinese freeways through mountainous areas. There are a few good analogs for a long, urban freeway tunnel: the A86 in Paris (6.2 miles), the M30 in Madrid (6.2 miles, though not continuous), and the Yamate Tunnel on the C2 Shuto Expressway (6.8 miles). For other urban highway tunnels, we have Brisbane Airport Link (4.2 miles) and Sydney’s Lane Cove Tunnel (2.2 miles).

If these sound suspiciously like the same countries have much lower per-mile transit construction capital costs than the US, well, more on that later.

These tunnels basically fall into two categories: tolled urban tunnels, and mountainous national network highway tunnels. (The M30 is urban, but free.)

National Highway Network Tunnels

The mountainous national network highway tunnels generally offer an enormous improvement over previous routes. They may also be what we might call “transportation equity projects” in the US, by which I mean projects that probably do not make sense on a cost-benefit basis, but that the nation feels obligated to build in order to provide high speed transportation to more remote regions. These tunnels all face geologic challenges related to deep rock tunneling, including areas with thousands of feet of overburden (depth of rock above).

The Alps tunnels fall into the former category. This includes the St Gotthard (10.5 miles), Arlberg (8.7 miles), Frejus (8.0 miles), and Mt Blanc (7.2 miles) tunnels, among others. Some of these tunnels have tolls, which can be quite high – for example, Arlberg is 9 euros, while Mt Blanc is 41 euros. These tunnels bypass treacherous mountain routes and form critical economic links between France, Switzerland, and Italy.

The Norwegian long tunnels are equity projects. The two longest tunnels are on the E36, which connects Bergen to Oslo. Both the Laerdal (15.2 miles) and Gudvangen (7.1 miles) tunnels are single bore, one lane per direction. Even granting very favorable geology, the construction costs for the Laerdal Tunnel are impressively low – $157m in 2014 dollars, or just over $10m/mile. However, the traffic volumes are also very low, just 1,000 vehicles per day. If you assume 30 year bonds and 5% interest, that’s about $15 per vehicle to recover costs – and remember, the route has several tunnels.

The Chinese freeways offer huge improvements in travel time. Many have speculated that China is overbuilding infrastructure; I honestly have no idea if the G65 route from Xi’an to Chongqing warrants a freeway, though Ankang and Dazhou are sizeable cities. The use of tunnels on the G65 seems gratuitous; a cursory look at the terrain averted by the 11.2 mile long Zhongnanshan Tunnel  suggests that the freeway could have easily climbed higher into the mountains and used a shorter tunnel. On the other hand, when you’re rolling in capital and you can throw down dual-bore two-lane freeway tunnels for $42m/mile, why not?

Taiwan’s longest freeway tunnel, the 8.0 mile dual-bore Xueshan Tunnel, is both a significant route improvement and an equity project. It connects Taipei to the relatively undeveloped eastern side of the island (Yilan, Hualien, and Taitung combined are barely 1 million people). The project took 15 years to complete, at a cost of $3.25b or about $405m/mile.

Urban Toll Tunnels

In contrast, the urban toll tunnels are all shallow tunnels, mainly through sedimentary deposits, with some shallow bedrock (limestone in the case of the A86, tuff for Brisbane Airport Link). These projects face challenges related to navigating around and protecting existing infrastructure and buildings.

The A86 is a dual-bore tunnel in an innovative configuration that takes advantage of the ability to increase capacity by restricting one tunnel to low-clearance passenger vehicles. One tunnel is two decks with two lanes each way for passenger vehicles; the other is a single lane in each direction and permits trucks. The project was completed in 2011 for 2.2b euros, about $2.94b or $474m/mile. (Note, if you believe LA Metro’s cost estimate of about $5b for the ~5 mile dual bore tunnels for the 710, that puts French highway tunneling costs at about half of American costs.) Tolls are about $3-$10.

Costs for the M30 freeway tunnels are, like Spanish transit costs, almost unbelievably low. The project built 99 kilometers (61.5 miles) of freeway, including 56 km (34.8 miles) of tunnels, for 3.9b euros. The entire project was completed in just under 3 years, between September 2004 and mid 2007. Adjusting to 2014 US dollars puts the cost at $6b, or about $98m/mile. Costs for different tunnel segments are summarized below.

So for cut and cover, Spanish costs are around $100m/mile. For bored tunnels, about $225m/mile. As stated previously, the M30 is toll free.

The Yamate tunnel  was completed in 2007 and is approximately 100 feet deep, with 70% bored. I could not find a cost for the project. The toll is about $9. The tunnel is part of the Shuto Expressway network, which was privatized in 2005 as the Metropolitan Expressway Company. The roads and debts are owned by a separate holding company.

Less encouraging for the proposition of a privately-funded tunnel through Sepulveda Pass is the experience of two privately built and operated urban toll tunnels in Australia.

The Brisbane Airport Link cost $4.8b, including a grand total of 9.3 miles of tunnel  among many other components. Tolls were expected to be about $5 by the end of 2013. The project was troubled from the very start; the bond sales went poorly and values collapsed. The Product Disclosure Statement forecast traffic volumes of 193,000 per day at opening, rising to 291,000 by 2026. In reality, traffic volumes were about 86,000 in August 2012, and 48,000 in February 2013, when the operator went into receivership. The traffic projections were so egregiously wrong that Arup, the consultant that prepared them, has been sued by investors.

Sydney’s Lane Cove Tunnel is much shorter than the others discussed here, but I’m including it as a representative toll tunnel project. The tunnel cost $1.1b, or $575m/mile in 2014 dollars, and was built by the same consortium as the Brisbane Airport Link. The tunnel is part of the M2 freeway, with a toll of about $3, and the only alternative is a surface arterial. Nevertheless, the operator went into receivership in early 2010, and Transurban bought the assets for just $630m.

The travel time savings and traffic projections claimed by the two Australian tunnel projects should have been suspicious from the start. The Brisbane Airport Link claimed it would attract up to 291,000 total entries a day; for reference, the George Washington Bridge, with its 14 lanes of traffic, carries about 275,000 vehicles a day. (Note: point volumes and total entries are directly comparable; the Brisbane Airport Link has an intermediate entry/exit point, so it’s impossible to say what point volumes are on the link). The Lane Cove Tunnel claimed it would save up to 17 minutes of travel time, which at 50 mph over its 2.2 mile length implies an average speed of just 7 mph on alternate routes.

As one more data point, for large bore tunnels, this document reports a range of costs, all much less than the approximate $1b/mile suggested for projects like Sepulveda Pass. (Note, the document also suggests that LA will be able to achieve French costs for the 710.)

Sepulveda Pass – Somewhere in the Middle

Our little pass between the LA Basin and the Valley certainly isn’t in the same league as the mountain tunnels, as a look at profiles easily shows.

(Note: open each image up in its own tab to see them at the same scale.)

It’s also not an equity project since we already have freeways through the Santa Monica Mountains. On the other hand, it’s longer and deeper than the other urban tunnels. I didn’t even bother creating profiles for those tunnels, since they wouldn’t register at that scale.

A real assessment of the geology is obviously well beyond my abilities. For now, we can just acknowledge that at the ends, tunneling would be through alluvial deposits like the other urban tunnels, but in the middle, it would be through the complex folded and faulted sedimentary rocks of the Santa Monica Mountains. The mountainous tunnels are all through igneous and metamorphic formations like gneiss, which tend to be extremely competent bedrock, except for the Xueshan Tunnel. This tunnel traverses heavily folded and faulted sandstone of varying quality, with the easternmost  2.0 miles being very poor. The high permeability of the ground traversed by the Xueshan Tunnel made groundwater an enormous problem. This tunnel might therefore be the best analog for the Sepulveda Pass tunnel.

Auto Tunnels – Technically Feasible, But Are They Worth It?

My initial instinct was to write off an auto tunnel through Sepulveda Pass as impractical. However, upon review of long freeway tunnels, it’s pretty clear that the tunnel would be technically feasible and that the costs are not preposterous. Let’s assume an A86-type setup, where one tube would be two decks for low clearance vehicles (i.e. passenger cars) and the other tube would be for transit vehicles.

If it can be built for Xueshan Tunnel type costs, it would cost around $3b. At 5% for 30 years, the tunnel would need to generate about $16m per month in revenue to cover capital costs. Assuming 20 weekday equivalents per month, that’s about $800k per day. If the tunnel attracts 100,000 users a day (about a third of the current traffic volume through the pass), the average toll would be $8, though obviously it would be varied at different times of the day, depending on congestion. This is in line with rates charged by Metro Express Lanes on the 10 and the 110 high-occupancy toll (HOT) lanes, which max out at $1.40/mile, or about $11 for Sepulveda Pass.

However, the overall numbers from Metro Express Lanes aren’t encouraging for a Sepulveda Pass auto tunnel. Net revenue over the pilot year of the program was $19m – certainly making the project able to cover its own $210m capital cost (if it were required to do so) with enough money left over to spend on expansions or other improvements. Unfortunately, that’s an order of magnitude short of what would be needed to fund capital costs for a Sepulveda Pass tunnel, and it’s being collected over almost three times the distance.

The travel time math isn’t hard to do. At 60 mph, a tunnel would get you from Westwood to Sherman Oaks in 8 minutes. Even if the freeway were only averaging 20 mph, the tunnel would save you 16 minutes. Are there 100,000 people going through Sepulveda Pass every day that value their driving time at $30/hr? The experience of the Australian toll tunnels should make us think hard about that.

It seems likely that the finances for a tolled auto tunnel don’t pencil out, unless the project can be delivered for considerably lower capital costs. The topography of the pass is really not challenging for passenger vehicles. If express HOT lanes through the pass are desired, the first alternative should be converting existing lanes. If that is not possible, any new lanes should probably be built on the surface through further freeway widening, or as an elevated facility like those on the 110.

Do People Misunderstand the Utility of Cars?

The premise behind a lot of urbanist thought seems to be that there’s a fixed quantity of things you need to access, and the reason you drive is that those things aren’t close enough together. Therefore, if provided with a dense enough neighborhood, you won’t need to drive.

This is the idea behind the “slow transit is ok if there’s enough density” argument that folks have been using to defend slow streetcars and LRT. It doesn’t matter if the transit is slow if there’s a lot of destinations that are close enough together.

I think this misunderstands the utility of driving, and indeed, the utility of transportation in general.

The purpose of investment in transportation is to make it possible to travel more distance in less time. It’s not to provide access to some fixed quantity of things you need, it’s to increase the quantity of things you can access. This is true for both low-density and high-density areas. The difference is that in high-density areas, you can access more things for a given investment of time.

For example, you could live in Koreatown and work downtown. These are among the densest neighborhoods in LA, and you’ll have an incredible amount of amenities within walking distance. But if you want to hit the beach, you’ll have to go to Santa Monica or Venice. If you want awesome Chinese food, you’re going to have to go to the San Gabriel Valley. Or maybe you have friends that live in Hollywood that you want to visit. Or maybe you want to take a class that’s only offered at UCLA or CSU Northridge. Or maybe you just want to go walk around a different neighborhood for a change!

Slow transit doesn’t help you with any of that. And here’s the thing: even if K-town and Downtown get so dense as to offer all the amenities just mentioned, other parts of the city will inevitably evolve to offer different things. That’s just how cities work!

The appeal of driving isn’t that it makes it possible to access the things you need in a low-density area. It’s that speed makes it possible to access more things at any density. If transit is going to compete, it needs to compete with speed.

Walkabout: Naebang, Seoul

If you’re a politician, a big fancy consultant, or a global thought leader, what to do you do when you visit a major city in another part of the world? You probably fly into Shiny New Airy Spaces International Airport, hop on the Global Thought Leader High-Speed Rail Line, and head downtown where you visit a bunch of places with high-end amenities and architectural showpieces like stadiums and convention centers.

Then you come home, pass through an old, congested airport terminal, and stand on the curb breathing exhaust while you wait for a car service to pick you up, since very few US airports have high quality rail connections.

Any wonder that US politicians and global thought leaders are obsessed with airport transit and convention centers?

The problem is that as an international traveler, the way you experience a city’s transit system is very different from the way that ordinary people experience it. Most people riding transit aren’t going to the airport or convention center or stadium very often (unless they work there). The vast majority of transit riders are trying to go about some mundane daily business – going to work, school, or shopping – in the places that the system serves.

So, what should you do if you want to experience a city the way residents do? Easy, just get out a rail map, pick a random stop, get off there, and start walking around. If I have time and the system isn’t too expansive, I like to try to pick one midline stop and one suburban terminal. (In theory, this works just as well – if not better – with buses, but it’s often harder to figure out the frequently and span of service for bus routes on an unfamiliar system.)

Objection!

You want me to just pick a random stop that I don’t know anything about? Yes. In fact, this really doesn’t work in a city you know, since you probably have preconceived notions about the neighborhoods around most of the transit stops. The goal is to learn things you wouldn’t learn in a structured exploration.

What if I pick a boring neighborhood with nothing to do? Even better; you’re learning about a part of the city that the tourist bureau doesn’t want to show you.

What if I don’t speak the language? Even better! Now you’re experiencing a city the way recent immigrants might.

What if I pick a dangerous neighborhood? This is a potential concern. In general, many Americans (especially a certain generation that rhymes with Maybe Doomers) overestimate the level of danger in cities. Go during the day when it’s light out, and just act naturally.

What if I get lost? You have a smartphone, don’t you? Before you head out, scroll around the neighborhood in your maps app to load a bunch of data into the cache (phone memory) so that you can see where you are even without cell service. Also, there seems to be a lot more free WiFi in some countries, and you can almost always find a local restaurant or coffee shop that has WiFi nowadays.

If the stop spacing on the rail network is reasonable – like say, a mile or so – you can plan to walk between two stations, which helps give you a feel for what the city is like a little further from a transit node.

Okay, enough introduction. Here’s what I saw when I had a free day in Seoul, and a random jab at the map led me to Naebang.

Naebang Station

Seoul is a very dense city, so no matter where you go, you’re going to see some urban environments. I exited Naebang and headed east on Seocho-daero. (Note: streets in Seoul are often just numbered sequentially with a local neighborhood name, which can be a little confusing.)

Heading uphill, there’s this Flatiron-esque building on a triangular lot.

This street is actually pretty wide an auto-oriented, like many modern arterials in Seoul. Neighborhood streets are a different story, as we’ll see later.

Seocho-daero leads you uphill and dead-ends; look back and you’ll be rewarded with some views. Urbanization in Asia is far more advanced than anywhere in the US outside Manhattan.

In the distance, you can see some green hills. Seoul’s dense urban environment is frequently broken up by hills, many of which form nice neighborhood parks. In a way it’s a little like. . .  Los Angeles. Is Seoul a glimpse of a future denser LA? A thought for another time.

Turning around, it’s time to head up into Seoripul Park.

There are some nice, graded paths, but why not scramble up some rocks when you can?

Just a little ways up, I reconnected with the main path through the park.

Seoul is dry in the winter, but has a summer monsoon that dumps a lot of rain. That keeps things very green in the hills.

So. . . dense. . . and yet the parks provide a real escape from the city.

Alright, now we’re back out into some steep streets fronting up onto the hills. I like the merciless use of overhead power distribution. Also, it does snow in Seoul in the winter, pretty regularly. Next time I go, I want to go in winter and see how people navigate those hills in snow.

Off of the arterials, you can see part of how Seoul achieves such density – really narrow side streets.

Of course, all those towers help too.

I kept walking downhill. Narrow streets and mid-rise development abound.

And hey, I was able to find where this is in Google Maps!

I kept wrapping around the hill on the street, into a neighborhood that looked a little more upscale. Nice sidewalks!

The building on the left was completed after Google street view’s last pass.

Seoul – not scared of funky design.

Oh, and one more thing: all those mid-rises in the upscale neighborhood? They’re all podiums with parking on the ground floor. Ha!