Monthly Archives: May 2013

Shuttle Envy

The Guardian casts its eyes on the Bay Area and sees Silicon Valley’s fleet of hundreds of private buses plying the streets of San Francisco. The paper turns up a few stereotypical SF residents who bash a shuttle-shaped piñata and complain about the shuttle service being “separate but not equal” or “segmentation”. I’m not sure how you could really be peeved about the Silicon Valley shuttles – why should it be Google’s job to improve transit services for the general public in San Francisco?

The shuttles are clearly performing a useful service. An equivalent public transit trip, say from the Inner Sunset to Apple’s campus, would involve SF Muni, Caltrain, and VTA bus, and take you almost 2.5 hours, assuming no delays. People that live in SF and work in Silicon Valley can afford to pay for cars and parking. If the 2.5-hour public transit trip is the only alternative, they’re all going to hop in their cars and cruise down the 280. The shuttles are mass (if not public) transit, fulfilling a need not met by existing public transit services.

As I noted on Twitter, the shuttle hate is symbolic: SF kvetchers don’t have a problem with the shuttles, they have a problem with the people on the shuttles. If we were talking about other private transit services that meet market demand not being served by public transit, like the gypsy cabs and dollar cabs of NYC, no one would be complaining. There are real issues from the tech boom, like housing affordability and SF becoming a Millennial playground, but they are not the fault of the shuttles.

When you consider anger towards the shuttles in light of poor quality service on SF Muni, what we have is Nietzsche’s psychology of human resentment: we have crappy transit service. Therefore, it is only fair that software engineers have crappy transit service as well. It is a lot easier, in terms of both physical and mental effort, to cast yourself as a victim. But as SF Weekly has reported, SF spends more money per capita than just about any city in the country, SF Muni’s rolling stock is in terrible condition, and its budget is routinely raided to shore up other departments. SF is a liberal city that supposedly cares a lot about transit. It is not a poor city. If SF Muni buses and trains are crowded and unreliable, the blame lies with SF voters for doing nothing about it, not with Silicon Valley tech companies providing service to their employees.

The industry responds, accurately, that the shuttles are beneficial, and that for their part, employees are paying high taxes without getting great services in return. To which I say, you’re all welcome to come to Los Angeles. Our weather is even better, and thanks to our polycentric nature, employees who want city life will have more than one option located 45 miles away from your HQ. Also, we don’t have a problem with rich people’s transportation habits or conspicuous consumption; it’s actually kind of one of our things, as long as it’s not Biebs terrorizing people in his Ferrari. Don’t take my word for it; dial up Elon Musk and ask him – it’s working out for him other than traffic on the 405 making him want to spend his personal money on freeway improvements. Just sayin’.

Transit Performance Metrics

A recent tweet from Market Urbanism about bus bunching early along the route of the B35 got me thinking about the ways we measure transit performance. Given the bias towards big capital projects in the US, it’s not surprising that our service performance metrics can be a little underpowered. I couldn’t find a service policy for NYCMTA on their website, but I did scare up LACMTA’s 2011 Transit Service Policy for here in Los Angeles and the MBTA’s 2010 Service Delivery Policy for Boston. If anyone knows where to find a similar standard for NYCMTA, I’d be happy to update this post to include it.

Note: for this post, I’m talking only about measuring the operational quality of the transit services we have chosen to provide, not the quality derived from things like span of service, frequency of service, and coverage of service, and not measures of efficiency that are also sometimes conflated with quality.

LACMTA’s policy on service quality is remarkably brief (see page 33 of the pdf). Quality is measured by on-time performance (OTP), with a  target threshold of 80%, and the volume of customer complaints, relative to an established baseline that references complaints on the poorest performing routes in 2008. This shows that the tools for measuring transit performance in Los Angeles have not yet caught up to our increasing dedication to expanding the system, as manifested by Measure R.

OTP is the easiest thing to measure, but unfortunately, for many transit services, it’s the least relevant to passengers. On-time departures and arrivals are important for long headway services, like commuter rail and low-frequency bus, where passengers time their arrivals at the stop to a published schedule. If you use a service that comes every hour or half-hour, like say Metro Local 158, you don’t just roll up to the stop whenever and wait for a bus. In this case, the bus being late translates directly into delays for you.

A Better Way to Measure Long-Headway Service

For long-headway transit, problems during the peak period have more of an impact on the perception of service quality than problems late at night, because more people are riding during peak periods. A late trip during the peak period delays more people than a late off-peak trip. Therefore, for long-headway service, we should look at the passenger-weighted OTP.


Where OTPi is the on-time performance for trip i, and ni is the number of passengers on trip i. For example, consider a commuter rail service with 5 peak period trains carrying 1,500 people each, and 15 off-peak trains carrying 100 people each. Under conventional OTP, if any one of the trains is delayed, OTP will be 95%. With PWOTP, a delay to a peak period train results in performance of 83%. A delay to an off-peak train results in performance of 99%.

Now, you could have 4 off-peak trains be delayed and still meet a 95% PWOTP threshold, and that doesn’t seem like great service either. So I think the way to go for long-headway services is to say both OTP and PWOTP need to meet a policy threshold. The current policy, which is just OTP, lets operators meet their standards by running a bunch of on-time trips late at night to make up for things being fouled up during rush hour.

What’s Important For Short-Headway Service?

If we’re talking about short-headway service, OTP of individual transit vehicles doesn’t really matter. What matters is headway regularity and travel-time reliability.

Headway regularity is important on a short-headway service because passengers don’t time their arrivals at the stop to the schedules for individual trips. The Blue Line runs every 6 minutes during rush hour, so if you need to ride, you just go the station, knowing that it will never be very long until a train comes – as long as the headways are hewing to the schedule. So for the Blue Line during rush hour, a much better performance metric is something that relates to headways. Note that if headways have become irregular, not many people are going to be on the trips with a short headway, but a lot of people are going to be stuck waiting for the trips with a long headway. Therefore, the long headway trip is more important to perceptions of service quality.

Travel-time reliability is pretty self-explanatory and serves as a substitute for OTP for short-headway services. If a specific trip departs five minutes late and arrives five minutes late, that’s irrelevant from a passenger’s point of view if the headway regularity is good.

Now back to Market Urbanism’s tweet. Note that if your service performance metric is OTP, your dispatchers might be incentivized to pursue operational strategies that make the service worse for your passengers.

Let’s consider a simple example. A bus route operates on 10 minute headways. The buses operating trips A, B, and C are approaching one end of the route, where they will turn for trips A’, B’, and C’. Due to disturbances along the route, trips A and C are 9 minutes behind schedule, meaning that trip B is on-time and only 1 minute behind trip A. The best thing to do for passengers would be to hold the bus operating trip B at the end of the route for 9 minutes, and start trip B’ 9 minutes late, because this would restore 10 minute headways for B’ and C’.

However, if the only performance metric is OTP, this strategy will make the apparent quality of service go down, because now B’ is late as well as A’ and C’. This encourages dispatchers to boost OTP by sending out B’ at the scheduled time, even though it will make things worse for passengers. Note that this strategy is also detrimental to travel-time reliability, because the long headway in front of C’ will ensure that it faces a higher than normal passenger load, further throwing that vehicle off schedule.

How Should We Measure Short-Headway Service?

The MBTA’s policy is a step ahead of LACMTA regarding short-headway service, because it uses headway-related metrics for all rapid transit services, and for bus services that operate at a headway of 10 minutes of less. It also uses trip-time metrics for these service. The MBTA’s policy (see pages 10-11 of the pdf) is for trips to operate within 1.5 times the scheduled headway, and within specified ranges relative to scheduled travel time.

That’s much better than OTP, but it’s not sensitive to the magnitude of headway variability. I can think of a few other things we ought to measure to get a really good picture of service quality. For short-headway service, we should look at the passenger-weighted average wait time (PWAWT), passenger waits exceeding threshold (PWET), passenger-weighted excess wait time (PWEWT), or standard deviation of headway.

Passenger-Weighted Average Wait Time (PWAWT)

PWAWT is just a weighted average of how long passengers weight. An unweighted average would just be equal to half the scheduled headway, regardless of headway variability. The weighted average accounts for the fact that more people wait for the longer headway trip. PWAWT will always be greater than half the schedule headway.


Where ni is the number of passengers on trip i, and hi is the headway on trip i. Note that for the short-headway services, we are assuming uniform passenger arrivals  during each interval between trips, which allows us to assume the average weight time for each trip is 0.5hi. If we assume that passenger arrivals are uniform throughout the entire period in question, then the number of passengers is just a linear function of the headway, and we don’t even need to know how many passengers are on each trip. It should go without saying that the schedule headway must be constant throughout the period in question if we are using PWAWT.

Passenger Waits Exceeding Threshold (PWET)

PWET, the percentage of passengers whose wait exceeds a threshold, could be used if we wanted to look at a period without a constant headway, like the entire day. The threshold could be absolute, e.g. must wait longer than headway plus 2 minutes, or relative, e.g. must wait longer than 1.25 headways. For the example below, I’m going to set the threshold at headway plus 1 minute, because you start to get annoyed about waiting pretty quickly when your wait goes beyond one headway.


This one’s a little more complicated, so a quick explanation: the denominator is just the total number of passengers. The numerator is an if statement that tells us to do nothing if the headway for trip i is less than the threshold, since no passengers for that trip experienced a wait that was too long. If the headway is greater than the threshold, we add the number of passengers who waited for too long, assuming uniform passenger arrivals during that headway period. Note that if we are looking at a period with variable headways, we probably can’t assume that passenger arrivals are uniform for the entire period, so we need to know the number of passengers for each trip.

The weakness of PWET would be that it treats all delays beyond the threshold the same, when the magnitude is obviously important. Passengers are more annoyed if they have to wait an extra 5 minutes versus an extra 1 minute. PWAWT and PWET together might give a good picture.

Passenger-Weighted Excess Wait Time (PWEWT)

PWEWT would allow for a weighted-average metric that emphasizes the importance of very long headways without requiring headways to be constant throughout the period of analysis. It would be a weighted-average of only the excess wait time, and could be defined either with an absolute threshold or a relative threshold. Relative to an absolute threshold, where hsi is the scheduled headway for trip i:


For PWEWT with a relative threshold of bh, just replace every hsi + a in the previous formulation with bhsi.

Standard Deviation of Headway

An alternate to PWAWT, PWET, and PWEWT would be to use the standard deviation of headway*. For example, if the policy guideline for standard deviation of headway was set at 25% of schedule headway, that would result in a service that met the an MBTA type policy with a 95% threshold, and exhibited less variability than is possible under that policy alone. Standard deviation could only be used for periods with constant scheduled headways.

Note that any of these standards would encourage the dispatchers to pursue operational strategies beneficial to passengers. In the past, it might have been difficult to calculate these statistics and figure out the best real-time operational strategies, but with technology like modern AFC and AVI, it shouldn’t be hard.

Enough Theory, Show Me Some Examples

Continuing from the previous example, let’s assume we dispatch B’ on time and C’ is 9 minutes late. For these two trips, OTP is 50%. By the MBTA’s 1.5 times headway standard, 50% of trips meet the policy. The PWAWT is 9.05 minutes. Therefore, if buses are bunched in groups of two along the route, passengers must expect to wait almost an entire published headway for service. The PWET is 40%. Assuming a threshold of h + 1, the PWEWT is 1.6 minutes.

Now let’s assume that the OTP threshold is 5 minutes, and the dispatcher decides to try to help passengers out without hurting OTP stats, so he holds B’ for 4 minutes. Now, B’ departs with a 5 minute headway and C’ with a 15 minute headway. OTP is 50%, but now 100% of trips meet the MBTA’s policy. The PWAWT is 6.25 minutes, a major improvement. The PWET is 20% and the PWEWT is 0.4 minutes.

Finally, if the dispatcher holds B’ for 9 minutes, then both B’ and C’ depart with 10 minute headways. OTP is 0%, but the PWAWT goes down to 5.00 minutes. PWET is 0% and PWEWT is 0 minutes. Note that most of the improvement comes on the front end of the hold, so even holding a bus for a few minutes can do a lot in terms of headway regularity. This is an important insight because it may be desirable to not hold B’ for the full 9 minutes, in order to save some operational flexibility for later in the dispatch period. A bus that is early can always be held more, but it is very difficult for a late bus to catch up to schedule.

Some thoughts: the MBTA standard isn’t a bad proxy, but it’s still imprecise. A service that swung between 5 minute and 15 minute headways would satisfy the MBTA’s policy, and generate PWAWT of 6.25 minutes and PWEWT of 0.4 minutes. The metrics don’t sound that bad, but this doesn’t seem like a great service. That suggests that we are going to use PWAWT and PWEWT, the standard needs to be pretty tight. PWET makes an important contribution here, because PWET of 20% definitely sounds bad.

I’ve also prepared a more detailed example that looks at these metrics under a somewhat random distribution of buses (as random as my mind can make it on the fly), a moderate bunching scenario, and a severe bunching scenario. The premise is a 10-minute headway service, with OTP threshold of 5 minutes and PWET/PWEWT threshold of 11 minutes. Moderate bunching assumes alternating 5 and 15 minute headways. Severe bunching assumes alternating headways of 1 and 19 minutes. Buses are held for a maximum of 4 minutes under partial holds, and for as long as needed to balance headways under full holds. The results are in the table below. (Contact me if you’d like the source spreadsheet.)



OTP metrics are appropriate for long-headway services, but they should be passenger-weighted. They are inappropriate for short-headway services, which should be measured by metrics like the MBTA’s headway variability standard, PWAWT, PWET, and PWEWT. Agencies should set standards and then define dispatcher procedures that will improve these metrics. As was seen in both the brief example and the detailed example, even when bus bunching is bad, short holds can have a significant impact on improving passenger experience.

Of course, we haven’t broached the subject of what the headway and OTP thresholds should be, but that’s a topic for another time.

*In fact, PWAWT, PWET, and PWEWT can be expressed as a function of the standard deviation.

Orange Crushed?

A recent article on capacity constraints on LA’s Orange Line BRT has been making the rounds in the transit blogosphere, and people have been revealing some serious bus bias. Ridership on the Orange Line currently exceeds 30k on weekdays, and in LA the line is generally considered to be successful beyond expectations. That ridership has led to crowding and warnings that the system is at capacity, and rail activists have been holding this up as a reason to invest in rail transit instead of BRT.

Now first of all, you should consider the source: Zev Yaroslavsky, one of the proponents of building the Orange Line BRT. The success of the Orange Line is good politics for him, and if these “capacity issues” are somehow resolved, allowing increased service, that will make him look even better. There’s nothing wrong with that; he’s a politician and he has to answer to his constituents. When a popular service is introduced on your watch, you take some credit, and you promise to make it even better. That’s what politicians do.

So, you shouldn’t take it as an article of faith that the Orange Line is at capacity. That statement is based on the current system running 4 minute headways. The reason that headways are limited to 4 minutes is that LADOT decided to limit them to 4 minutes. There are plenty of other east-west roadways in the Valley, and they conflict with the same north-south roadways as the Orange Line. They meet at regular intersections with regular traffic lights, and they get more than 2 vehicles through every 4 minutes.

It would be fairly easy to retime the traffic lights and improve the transit priority to allow more Orange Line buses through, and in fact, the article says that LACMTA and LADOT are looking at doing just that: by either allowing shorter but more frequent green lights to reduce headway, or allowing two buses to proceed through the intersection in tandem. Note that the station platforms are long enough for double-berthing of buses, so if the traffic lights can be adjusted to allow two buses through in one green phase, the capacity of the line could be effectively doubled without building any new infrastructure. You’d also have the option of running some express service to West Valley, since the stations have pullouts. Simply put, if you are using the Orange Line as an example of BRT being maxed out, you might as well just come out and say that you really like trains and you really don’t like buses.

There are two intersections that I can see as being more challenging than the rest. The first is Burbank and Fulton at the Valley College Station. The Orange Line crosses this intersection on a diagonal, requiring a third signal phase. There is the need to serve two major roadways instead of just one. The other is at Woodman Station, where the Orange Line crosses both Woodman and Oxnard within about 200-300 feet of the intersection of Woodman and Oxnard, so you need some serious coordination between all of those signals. The good news is that if those intersections prove too difficult, LA doesn’t have a problem with pouring concrete to fix it. It would cost some money, but still be much cheaper than converting the entire Orange Line to LRT.

Okay, what if Ben Bernanke decides to do a helicopter drop on Metro and credit our bank accounts with enough free cash to upgrade the Orange Line to LRT? We still shouldn’t do it. Take a look at the San Fernando Valley. It’s not like the Orange Line follows some high-density corridor and everything else is empty. The Valley is prototypical LA – somewhat uniform medium density with a focus on the major arterials. There’s no compelling need to focus transit improvements on the Orange Line.

If Bernanke cuts that check for improving east-west transit in the Valley, here are few things that would be a much better use of the money than converting the Orange Line to LRT. I’m sure there are others; these are just off the top of my head:

  • Building a rapid transit service (type TBD) along Ventura Blvd from Valley Circle to Universal City. The bus routes serving Ventura Blvd today, 150 and 750, already pull about 16k in weekday ridership. This line could continue east to serve Burbank, Glendale, and Pasadena and people who commute on the 101, the 134, and the 210. Note that this is one of the greatest strengths of the LA development pattern – you can conceive a totally rational and useful transit service that doesn’t go anywhere near downtown. Take that, Urban Ring.
  • Extend the Orange Line east to Burbank on the existing rail ROW. Again, you could continue east from there if you wanted.
  • Build some infill stops on the Ventura Line and run a DMU service between LA Union Station and Chatsworth.

And the really awesome thing is, thanks to the success of the Orange Line, people in the Valley want more transit! Think about that. In less than 8 years of operations, we’ve gone from being legally unable to build LRT in the Valley to debating how to fund a rail line from Sylmar to El Segundo. In that light, I don’t think you can say the Orange Line is anything other than a success. The only reason to hate on the Orange Line is that you just can’t stand the sight of a successful BRT.

A Framework for Thinking About Long-Distance Travel

There’s been a lot of back and forth over the utility of Amtrak’s long-distance routes. Unlike regional services on the Northeast Corridor, these services don’t make enough money in fare revenue to cover their operating costs. To start, I think we need a good framework for looking at the alternatives, which as I see it, are as follows: do nothing, air, rail, bus, and car. Note that it is always important do include the do-nothing alternative, because transportation modes compete not only with each other but with the option of not making the trip at all.

To help compare these alternatives, I’m borrowing some graphical methodology from Cap’n Transit’s posts on commute options. Here are the five alternatives plotted with travel time versus cost for a representative trip, Chicago to Los Angeles.


And here they are with connectivity versus travel time.


I’m assigning an off-the-cuff assessment of connectivity rather than trying to come up with some numerical index. Feel free to debate the specifics but the relative rankings are sound. Doing nothing obviously gets you no connectivity. Your car takes you anywhere. Air offers very limited connectivity when it comes to intermediate destinations because, unlike a train or bus or car, the plane can’t make lots of stops en route. Bus and rail are somewhere between air and car. I’m putting bus above rail because bus currently serves more destinations, and because given the existing highway and rail networks in the United States, bus service could be scaled up more quickly. The difference in connectivity between modes is an important consideration for understanding which trips they are competing for.

Where does this leave us regarding long-distance Amtrak trains? For starters, I think it suggests that we cannot drive a huge modal shift from air to anything else other than doing nothing. Overwhelmingly, air and doing nothing compete only with each other. Air is far and away the fastest option for long distance travel, and it is not appreciably more expensive. The vast majority of air trips – business, personal, and freight – simply cannot tolerate having their travel time increased from 6 hours to 2 days. I live in LA, but I have a lot of family on the east coast. If it takes me 3 days to get there, I’m going to visit them less often. If we raise the cost of air travel, many trips will simply vanish.

Now, maybe you think a smaller total volume of cross country travel is a good thing. But that’s a different argument than shifting people from planes to trains, and you have to consider the potential for economic losses. That’s a topic for another post.

However, that analysis regarding air travel only holds up if air travel actually serves your origin and destination. As many have pointed out, lots of people riding long distance trains (and we can assume the same for bus) are not going from Chicago to Los Angeles. They are going from, say, Dodge City, KS to Winslow, AZ. Let’s rerun the time-cost analysis using those cities.


And that’s not even considering that the air option is probably subsidized by the Essential Air Service (EAS) program. We are clearly operating in a different space, and it’s easy to see why: air networks are fundamentally different than rail and bus networks. Serving large cities capitalizes on all the strengths of the air mode, while serving small cities highlights all the weaknesses. The opposite is true for bus and rail; serving small cities highlights their strength: the ability to aggregate trips with different origins and destinations onto the same trip. For these types of trips, air will never be able to compete with rail and bus (and car).

So, if the objective is to get fewer people to drive, the choice is between bus and train, and each offers different advantages. Rail offers a smoother, more comfortable ride, and it’s easier to get up and walk around the train. There is no question that riding on a train is a nicer experience. On the other hand, bus could immediately serve a set of origin-destination pairs that is an order of magnitude larger, and offer greater frequency.

My initial sense is that in the short-term, expanding bus service makes more sense in this case for one reason: infrastructure capital costs. Intercity bus service could be greatly increased without needing anything other more buses and perhaps increased bus terminal, layover, and maintenance space in some cities.

On the other hand, all of the long-distance rail routes are owned and operated by these guys, and I think it is indicative of transportation myopia on the part of a lot of transit activists that we’ve gone this far in the discussion of Amtrak and hardly even mentioned them. Any attempt at major expansion of long-distance passenger rail is going to result in the freight railroads demanding capital improvements. And why shouldn’t they? Here is an industry that, over the last 50 years, has been nearly strangled to death by overregulation and direct government subsidy of their competition, and not only have they survived, they’re killing it. They’re blowing trucking out of the water and dropping billions in private cash on capacity enhancements every year. If you’re a Class I RR, a money-losing passenger service is just another imposition by the federal government that hurts the viability of your business.

At this point, someone is going to note that both cars and bus service are subsidized by the provision of public highways and freeways. True enough. I see no technical reason that you couldn’t increase the cost of using highways to the point that passenger rail becomes profitable.

But if passenger rail becomes profitable, there’s no need for Amtrak anyway. The whole reason Amtrak exists is that passenger rail is not profitable. If passenger trains would make money and be a good use of track capacity, the Class I’s would start to run them. In fact, given how efficient the Class I’s are, they could probably reach profitability with lower ridership and/or lower fares than Amtrak. Tri-Rail doesn’t make any money but FEC seems to think they might be able to on a largely parallel facility.

So what’s the conclusion? I don’t know. Hey, no one said this was an easy question. I think it is clear that for long-distance travel that is not between two major cities, air isn’t going to cut it. In the short-term, increased intercity bus would seem to be the most readily achievable option. But there just aren’t that many trips being made between these minor city pairs anyway. According to the Kansas DOT, the AADT on US 56 west of Dodge City is 2,950. How many of those trips could possibly be served by long-distance transit in the first place? If the rural states want to pay for these services or have the feds chip in a little, I’m cool with that. If they don’t, I’m cool with that too. These trips are not the best type of trip to be served by transit and they are the type of trip where the weaknesses of cars matter the least. Transit advocates should have much bigger fish to fry than worrying about how people in Dodge City get around.

Note: travel times and cost based on Amtrak, Greyhound, and Kayak searches for a one-way trip leaving on May 15, 2013. For the small cities, I used Winslow for rail, Show Low for air, and Holbrook for bus (Amtrak serves only Winslow and Greyhound only Holbrook). I added an hour of travel time to get from Show Low to Winslow. The other airport option is Flagstaff and it is about the same distance/cost. For driving times, I used the Google Maps drive time and assumed two people driving 16 hours out of the day. For driving cost, I used $0.608/mile. You can tweak all of these assumptions; they are just rounding errors compared to the overall outcome.

Gas Taxes Are Not User Fees

I wasn’t planning on making the first post on this blog about gas taxes, but transpo funding is in the news a lot lately, and I’m getting sick of writing the same comment over and over again on Streetsblog, The Atlantic Cities, etc.

America’s infrastructure could use some sprucing up. If you live in the Northeast or Midwest, your bridges are rusting away from years of road salt. If you ride one of America’s big legacy transit systems, every day you’re putting your safety in the hands of components so old they can’t even be replaced, because no one makes them anymore.

So, where should we get the money to address this problem? That’s easy. Currently, the federal government can borrow money at negative real interest rates. Considering that any tax increase is going to have a negative effect on aggregate demand, which is the last thing the economy needs right now, it’s an open and shut case.

However, as is usually the case in America, the obvious policy solution is blocked by political intransigence, so lately the debate has been about how to raise more revenue. With a hike in the gas tax off the table, other ideas like a vehicle-miles tax (VMT) have been floated. The basic idea of the VMT is that everyone pays a fixed rate for each mile they travel, with miles traveled being recorded through low-tech means like odometer readings or high-tech means like GPS. For reasons I fail to comprehend, the VMT is getting a lot of traction in the progressive community, capped off by a recent GAO report that declared the VMT more “efficient and equitable”. But in fact, the VMT is a bad idea, and by supporting it, progressives are doing a huge disservice to the cause of better pedestrian, bicycle, and transit facilities.

The supposed benefit of the VMT is that it charges people based on how much they use roads – in effect it’s a user fee. Later, we’ll get to why that’s a bad idea in and of itself, but for now, note that the gas tax can be considered a de facto user fee. The more you drive, the more gas you use, and the more you pay. In addition, the gas tax has the benefit of making people who drive inefficient vehicles pay more. A VMT rewards people who drive Escalades at the expense of people who drive Volts. How is that more “equitable” than the gas tax? Sure, you could make the VMT higher for vehicles that are less efficient, but why go to all that trouble?

Which brings us to the second reason the VMT is a bad idea – it is complicated to implement. Any system, from low-tech odometer readings to high-tech GPS, would be subject to rampant fraud. High-tech systems like GPS would require every vehicle in the country to be outfitted with a VMT unit, at considerable expense. The GAO found that depending on the system, up to 33% of the revenue would be lost to implementation costs. Compared to a gas tax hike, which would lose 0% of revenue to implementation costs, how is that more “efficient”?

But wait, didn’t we say that a gas tax hike was off the table? Ah, now we’re getting somewhere. Why is a gas tax hike off the table? Because politicians decided it was off the table. So my question to progressives is this: do you really think that GOP pols will reflexively block any increase in the gas tax, but are perfectly willing to go tell the Agenda 21 crowd that they all have to install government-monitored GPS units in their cars? It’s just ridiculous. No Republican politician takes the VMT seriously. It’s a red herring, an issue that can be used to distract from the need to raise the gas tax. They’ll call for studies of the VMT, and then cite privacy concerns and implementation difficulties as reasons it won’t work.

Beyond all of this, though, if progressives engage in the debate using the “user fee” framework, we’ve already lost, no matter what the outcome. A lot of people have jumped on the “drivers should pay the full cost of roads” bandwagon just because they don’t like cars. But the obvious next step in the argument is that transit riders should pay the full cost of transit, bicyclists should pay the full cost of bike improvements, and so on. The likes of Cato and Reason, who love highway user fee concepts, already make that argument. If you look at the gas tax or VMT as a user fee, you’ve set yourself up for Randall O’Toole to make a convincing argument that gas taxes and VMTs should only fund highways.

Okay, so if the gas tax isn’t a user fee, then why do we have it? Simple. It’s a tax on the negative externalities, which include pollution, climate change, noise, and so on.

Here’s the right way to think about it. On one side, we have public goods that cost money – things like schools, roads, transit, etc. Some projects are better than others and more deserving of funding. On the other side, we need to raise revenue, and there are better and worse ways of raising revenue. The gas tax is a great way to raise revenue because it imposes a cost for generating negative externalities in direct proportion to the rate at which a vehicle produces those externalities, and because it already exists. A tax on bicycling would be a bad idea, because bikes generate positive externalities that we would like to increase. Similarly, a VMT punishes nascent alternative technologies that we ought to be encouraging. Note that by this logic, it is perfectly reasonable to have property or land taxes contribute to funding transportation – land is worthless without access to transportation, just like it is worthless without police to stop crime. We don’t demand that user fees pay for police service either.

Note that this framework also allows you to build a coherent argument for why the gas tax should be increased but transit fares should not. It obviates the “I pay for my roads so you pay for your bikes and trains” talking point – cycling and riding transit have positive externalities, so they should be promoted. It’s also the right way to argue in favor of HOT lanes and congestion pricing, which are taxes on the negative externalities of traffic congestion. The user free framework, on the other hand, is an argument you can’t win. It’s a trap.


As for the supposed fatal flaws of the gas tax, they are all weak arguments that fail to hold up to scrutiny:

  • Inflation: the easiest to dispense with. The argument goes that inflation has eroded the purchasing power of the gas tax. The obvious solution is to index the gas tax to inflation or construction costs or what have you, or periodically raise the gas tax. You know, like we did for 60 years.
  • Fuel efficiency: the argument here is that increasing fuel efficiency has made it impossible to raise enough money from the gas tax. Note that this is logically inconsistent with the idea that enough money can be raised from a VMT – as long as we are driving gasoline powered vehicles, a gas tax and a VMT can be seen as functionally equivalent, with the difference being that a gas tax is a tax on inputs and a VMT is a tax on outputs. Electric and natural gas vehicles may be an issue someday, but right now they are an inconsequential portion of the vehicle fleet. And at any rate, the data shows that in historical context, current increases in fuel efficiency are not out of scale with what happened in the 1970s.


  • Not popular with drivers: and the VMT won’t be either. Shockingly, people prefer not paying to paying.
  • Politically impossible: the same kind of thinking that leads people to argue for spending billions of dollars on trans-Hudson rail tunnels before maximizing existing capacity by through-routing.

At the end of the day, there is simply no compelling technical or economic reason to switch from gas taxes to VMTs. On top of that, a VMT would be a major victory for the kind of people who want to user-fee everything in the public realm. The VMT is counterproductive for progressive causes and we need to treat it as such. The answer is simple. Raise the gas tax because it is a charge on negative externalities.

Let’s Go LA

This blog is dedicated to the advancement of Greater Los Angeles, in the hope that I can make some small contribution towards greater prosperity and quality of life in the region.

The main focus of this blog will be transportation, land use, and economics. From there, a little politics is pretty much inevitable. Common themes will include freeway capacity management, transit improvements, zoning and permitting, and capitalizing on the region’s existing economic strengths. The interaction between these aspects of city growth will also be a major topic. I’ll bring in some ideas from the writers on the blogroll and apply them to LA to help think about which plans make sense and which plans don’t.

Geographically, by Greater Los Angeles, I basically mean LA County, Orange County, the Inland Empire (San Bernardino and Riverside Counties), and a little Ventura County for good measure. I’ll occasionally drift down to San Diego and up to the Bay Area. This is California, so water resources will pop up now and then, which means dealing with the Owens Valley, the State Water Project, and the whole Colorado Basin… and beyond. Sometimes I may just write about something elsewhere in the world that interests me, but I’m hoping to mainly stay focused on LA.

This blog is also something of an experiment. While I’m very interested in these things, I’m not entirely convinced I have anything new to say. Part of this is really just going to be me organizing my thoughts to figure that out. Maybe it grows into something more than just a blog. Or maybe I decide to just go back to annoying people on Twitter and in comments on their blogs. We’ll see.

From sun-drenched beaches to snow-capped mountains, the City of Industry to “the industry”, and Beverly Hills to Skid Row, LA’s geography and economy are as beautiful and diverse as its people. And we all make LA better. Let’s go LA.