Light Rail and Energy Use

Politics is full of premises that people take on faith without actually testing against facts.  One such premise is that light rail investments reduce energy use and CO2 output.  But data from the USDOT, as I posted before, shows that light rail at average occupancy and autos at average occupancy are in an energy dead heat.   Driving a hybrid or even high fuel efficiency conventional automobile, even solo with no passengers, uses less energy and produces less CO2 per passenger-mile than light rail.

A group critical of the Denver light rail system brings us another data point.  In their report (pdf), compiled from the official figures of the Denver transit authority, they claim:  (via the Anti-Planner)

Denver's light-rail trains use 4,400 British thermal units (BTUs) and produce 0.78 pounds of CO2 per passenger mile. By comparison, the average SUV uses about 4,400 British thermal units (BTUs) and produces 0.69 pounds of CO2 per passenger mile.47 In other words, people who ride Denver's light rail when gasoline prices rise are not saving energy: they are merely imposing their energy costs on other taxpayers. If oil prices rise again, people can save more energy by buying more fuel-efficient cars than by riding energy intensive rail transit lines

Quite a while back, I made a light rail bet.  I said that for the capital cost of constructing these systems, I could purchase every regular rider a Prius, and with the annual operating deficit each year could purchase gas for all these Prius's for a full year.  This bet has not yet proved wrong (LA example), even for heavy rail (Albuquerque example).  Now,though, in addition to being more cost effective, the hybrid is also more energy efficient.

Postscript: I am sometimes criticized for not including the highway construction cost in my Prius bet.   First, a new highway lane has far more capacity than most light rail lines, and is far cheaper to build.  I don't think anyone, even light rail supporters, dispute this.  Light rail is generally supported over highways for what I would call aesthetic reasons -- light rail just strikes some people as more elegant a transportation solution.  All the traffic carried by most light rail lines is generally a small fraction of a single highway lane.  The congestion argument is a chimera, and is never supported, even in the fine print of transit authority statistics.  From Denver's internal projections:

Now, RTD says the line will cost more than $600 million, which is a lot for a mere 11 route miles. Moreover, RTD has changed the proposed technology to something it calls "electric multiple-unit commuter rail," which sounds something like the Chicago Electroliners or some of the Philadelphia commuter trains.

For this high price, the DEIS reports incredibly trivial benefits. The proposed rail line is projected to take 0.0085 percent of cars off the road. Of course, that's for the region as a whole, but in the corridor it will take a whopping 0.227 percent of cars off the road. A handful of buses could do as well.


  1. ColoComment:

    One factor in the auto v. light rail debate that I have not yet seen addressed is any opportunity cost that may be ascribed to weather for a commuter using either type of transportation. In a Denver winter snow or summer rain storm, commuter buses are slowed to the same limping stop and go pace, and subject to all the risk of vehicular collision and accident, as any other vehicle on that thoroughfare. OTOH, light rail continues to safely move passengers along at its usual rate of speed.
    Seems as though there should be some value attributed to that commuter time-savings, but I sure wouldn't know how to calculate that.

  2. Dr. T:

    "A handful of buses could do as well."

    But, buying a handful of buses will not generate the high level of bribe money and favors required by local politicians. I lived in southeastern Virginia when Norfolk and Virginia Beach were trying to put in a light rail connector. The claimed intent was to make it easier for tourists staying in the pricey hotels in Norfolk to go to the beach. However, surveys showed that the majority of light rail riders would be maids going from tenements in Norfolk to the beach hotels. A few appropriately scheduled buses would have met their needs, but light rail (at the heavy cost of five billion) was approved after six months of additional bribery.

  3. Danny Toone:

    I just want to make some distinctions here.

    First and foremost, you are comparing these two systems using metrics that are just poor metrics. Quantity of X per passenger mile is a metric that is too hard to apply for these situations. If you are strictly talking averages, then yes, it works, but when has the world ever worked in averages? You should know by now that one of the most deceptive words ever contrived was "average".

    See, with an automobile during rush hour, the energy use per passenger mile skyrockets. Cars slow down, run significantly less efficiently, and passengers per car tends to stay the same (where I live it is about 1.1 passengers per car including the driver). More cars, burning less efficiently, for longer periods of time, with no compensation with passenger density.

    During non rush hours, energy use per passenger mile drops low. Cars are running at full highway speed, burning more efficiently, and passenger density increases slightly.

    So first, tell me, how were these averages calculated? There are a million possibilities. I mean, I could take a random sample throughout the day, picking 5 cars every hour and averaging their energy output. But that would skew towards efficiency. If I decided to pick 100 randomly selected automobiles during rush hour, then that would skew towards inefficiency. Use your creative noggin here, there are hundreds of ways you could calculate this to suit your politics. How was this "average" calculated?

    Even calculating for light rail is tricky. During rush hour, energy use per passenger mile plummets. More passengers pack into the trainsets, and total energy use increases negligibly. The inverse relationship means that during rush hour, energy use per passenger mile is about as close to zero as you can get.

    During non rush hour periods, the opposite is true. The trainsets use approximately the same amount of energy full as they do empty. Running them during these periods would have an energy use per passenger profile approximately equal to a luxury yacht.

    So, again, the same question. How are these "averages" calculated? They can be infinitely skewed to fit anybody's ideology, which is the reason why the propaganda is always so conflicting and there are a million mythbuster style articles around claiming both sides of the story.

    The actual differences in operation costs (as well as energy use per passenger, etc) between light rail systems vary significantly with the total number of riders, not by any other metric. To compare, the operating costs of the Manilla Light Rail system in the Philippines is approaching US$0.02 per passenger mile. But that system has the highest ridership in the world, and is constantly running at capacity. From your estimates, a poorly designed system with low ridership will have operating costs running into the 10s of dollars per passenger mile.

    Now as far as your postscript, there are some bad misconceptions as well.

    A new highway lane has nowhere near the capacity of light rail. A highway lane can support a maximum of about 2000 cars per hour. Even running every single one of those cars with 5 passengers, that is only 10,000 passengers per hour. Light rail has been proven to be capable of greater than 50,000 passengers per hour, running at full capacity. But capacity is a dumb argument to make anyway, because so few systems run at capacity.

    By claiming that a new highway lane is cheaper to build, you are being overly selective in your calculation. The truth is that comparing a lane expansion to a new rail construction is not possible. To build a new lane on a highway, there are typically no new rights of way to be purchased, and if they are, an expansion of an existing right of way is incredibly easy and cheap. To build light rail, completely new rights of way must be purchased (or seized at "fair value"). If you want to make a comparison, why don't you obtain cost estimates to build a brand new freeway through the middle of downtown phoenix. Only by comparing in that manner can you truly find apples to apples.

    If you want a real comparison to building a new lane, then only select the costs of prepping and laying the tracks. The majority of light rail capital cost is in the right of way.

    I can understand your perspective. See, to you, most of the costs of freeways are already sunk and are irrelevant to the decision at hand. You had no say in building any of the interstate highway system, and as such, you aren't taking into account the original inflation adjusted cost of building the new massive rights of way for a freeway system. But we could do the same thing with light rail, if you would just close your eyes and ears for a while and let the idea of the cost of new rights of way to fade from your mind. In the end, your comparison is not a fair comparison.

    Now that I have come off as a totally whacked out light rail apologist, let me reveal the truth: I'm right with you. I hate practically every single light rail system in the United States. I think they are a waste of money, and worse, they are a waste of taxpayer which has been coerced with little consent and indirect accountability.

    But they haven't always been that way. There were literally thousands of privately owned light-rail-like railways throughout the united states prior to the 1940's. They were efficient, carried thousands of people at reasonable costs, and they earned profits (something a government owned light rail system has yet to replicate here). Why did they disappear? Most people would say that the car proved to be a superior mode of transportation.

    But that is not entirely true. It was a superior mode of transportation, but only at the extremely subsidized prices at which the government provided roads. Roads have always been funded by various combinations of income taxes, sales taxes, gas taxes, and property taxes. Gas taxes have always, and I mean always, been too low to fund road construction and maintenance by themselves...they have always been augmented by other taxes. As such, the prominence and superiority of the automobile is an illusion caused by government manipulation and distortion of the price system. Automobile drivers always pay a minimal percentage of their true costs when they purchase fuel at the pump...the rest of their costs are invisibly payed for.

    The automobile is clearly superior to light rail, but only when subsidized. In an unsubsidized world with $6-7/gallon gas, I think most people would think a little more about buying a car.

    Until government creates a more accurate way of passing off true costs to those that cause them, instead of those that don't, then light rail and other forms of mass transportation will always be costly and inefficient. You should notice that mass transportation ridership is highest in countries where gasoline taxes are highest, or where wealth is lowest. The inability to afford a car ensures high ridership of mass transportation, and like I said previously, ridership is the single most important metric to consider when calculating costs for a mass transportation system. I would even say it is the only important metric.

    Needless to say, I'm a bit cynical. We destroyed our extremely beneficial privately owned mass transportation system by subsidizing roads, which also resulted in massive urban sprawl and low population densities. Now that we are used to cheap gas, nobody wants to pay higher prices, despite the fact that an efficient market would require it. And since we have grown so addicted to our automobiles, we now have a society where everybody owns one, the highway system is a congested cluster#*#* and now we require mass transportation to ease the congestion. But since we have massive urban sprawl, and low population densities, mass transportation systems are guaranteed to have low ridership, which means that their costs are going to be too high, which means we have to subsidize mass transportation!!!

    Sorry for the rant, but this is what happens when you screw with the free market.

  4. deacon:

    "First, a new highway lane has far more capacity than most light rail lines, and is far cheaper to build. I don’t think anyone, even light rail supporters, dispute this."

    Ahem, a light rail line has many times the capacity of a highway lane especially at peak times when it matters most. Do the math.

    Light rail is more expensive to build because it is often shoved into parts of a city where it does not make sense, and engineers spend and inordinate amount of time and money trying not piss off auto-centric special interest groups.

  5. MJ:


    You claim not to be a light rail apologist, yet you make all the standard light rail apologist talking points. Now for a dose of reality.

    Averages are a perfectly acceptable way to look at energy use. Looking at longer-term trends in these averages tells us whether what we are doing is making the situation better or worse. In other words, it's what happens at the margins that count, and at the margins we are building very expensive and lightly used rail systems.

    As you mention, comparing theoretical capacities of different systems is unhelpful, especially in the case of U.S. light rail systems. In city where I live, the local planning agency has proposed a new light rail line. It plans for run the line at 7.5 minute headways with 2-car consists. Even using their definition of capacity, which involves crush loads of 160 passengers per car (66 is seated capacity), this line would only achieve a throughput of just over 2,500 passengers/hr/direction, something that even a relatively low-performing HOV lane can do. It is also a far cry from 50,000 passengers per hour.

    It also makes perfect sense to measure the costs of existing light rail systems for comparative purposes. Light rail lines are built within the right-of-way of existing streets because the trains have to take people to where they want to go and deliver them fairly close to their destinations, something that is difficult to accomplish if you are operating in the freeway median, as some propose. Also, right-of-way is not a major cost of these systems. The Hiawatha Line in Minneapolis has cost $740 million and counting, only $20 million of which was for right-of-way, and this was contributed in kind from the Minnesota DOT.

    The conspiracy theories about the demise of streetcar systems all fail uniformly because they don't look far enough back. Most privately-owned streetcar systems were running into financial trouble by the 1920s. Their decline in patronage was only briefly reversed by the Depression and World War II. Everything since has been a downward spiral.

    Those who claim this was all orchestrated by government give government entirely too much credit. I have a difficult time believing that government was able to take people's money and spend it entirely on something they did not want (especially prior to the advent of the welfare state). As early as the 1920s, fuel taxes were adopted to replace other types of charges to finance highways.

    Some of the hard-core rail fans and "green" types point disapprovingly to the fact that property taxes are used in many places to finance local roads and call this a "subsidy". I have a few reactions to this. First, local roads are the textbook definition of a public good: they are non-rival and non-excludable. Hence, charging everyone for them makes sense. Beyond that, local roads are not just used by drivers, they are also used by pedestrians, bicyclists, bus riders, etc. Why should drivers alone be the ones who pay. Third, I read a recent study that attempted to compare the level of charges motorists pay with the amount of costs they occasion (excluding externalities). It came out to about 76 percent -- not great, but believable, and much larger than the 20 percent or so that public transit users pay.

    It is also not correct to suggest that "unsubsidized" gas would cost $6-7 a gallon. Recent work by researchers at Resources for the Future have estimated the total external cost of road users to be around 10 cents/mile, or about $2.00 gallon. This is using the most liberal definition of exernalities plausible (e.g. congestion, crashes, noise, air pollution, climate change, etc.) Local gas stations are currently selling gas at around $1.85 a gallon, implying that, even if all externalities were accounted for, we'd still be short of the $4/gal we saw last summer. Yes, many European countries have much higher fuel tax rates, but 1) they also do not have the same set of regulations that U.S. automakers do, 2) they have been unable to achieve their Kyoto Protocol goals even with these tax levels, 3) There is no evidence that I have seen to suggest that these rates are optimal -- I have seen at least one paper that suggests they are higher than optimal.

    Which brings up another point: "sprawl", or as I like to call it, low-density development, is not uniquely American and is not the result of us allowing our streetcars to go the way of the dinosaurs. Many European cities, supposedly the pinnacle of "good" urban design, are starting to look more like American cities all the time. Development at the fringe is low-density and occupants often drive to accomplish most of their activities. Both outcomes are the inevitable result of rising incomes, not poor planning.

    Transportation in American cities is characterized by poor performance, and this is largely the result of government failure. Large transit deficits and heavy congestion are the inevitable result of pricing services below marginal cost. Sadly, government thinks it can improve one (congestion), by underpricing another (public transit). The excuses we get for why this doesn't work range from the silly (we "love" our cars) to the completely implausible (too little money).

    Blame whomever you like, but don't expect that a free market outcome will look anything like 1920s New York City.