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Opinion: How big are the environmental benefits of high-speed rail?

(The following column by Edward L. Glaeser appeared on the New York Times website on August 12, 2009. He is an economics professor at Harvard.)

NEW YORK ó How large are the environmental and other social benefits of high-speed rail?

Iíve now reached the halfway point in this series of blog posts on the presidentís ďvision for high-speed rail.Ē The national discussion of high-speed rail must get away from high-flying rhetoric and tawdry ad hominem attacks and start weighing costs and benefits.

Environmental benefits are one potentially big plus from rail lines.

Today, I focus only on the social benefits that come from switching travelers from cars and planes to rail, not any indirect benefits associated with changing land-use patterns. Iíll get to those next week, when I also discuss high-speed rail as an economic development strategy. As I did last week, I use a simple, transparent methodology, focusing on costs and benefits during an average year. Today, Iíll estimate the environmental and other social benefits that will help offset the costs of rail.

To estimate the social benefits of rail on ridership in any given corridor, I calculate:

(Number of riders who switch from cars to rail) times (Social costs of cars minus social costs of rail) plus (Number of riders who switch from air to rail) times (Social costs of air minus social costs of rail) minus (Number of new riders who are taking rail) times (Social costs of rail)

Iíd like to include buses, but this post is too long already. Only about 2 percent of inter-city vehicle miles are traveled by bus, and a Center for Clean Air Policy report has convinced me that buses wouldnít make much of a difference.

Iím going to ignore fatalities for both rail and air and noise externalities (typical estimates for these are modest), and ignore any traffic congestion associated with getting to and from the airport or train station. For both air and rail, the only social cost will be carbon emissions. For cars, Iíll add in traffic deaths, congestion and local pollution.

As in the previous two posts, I focus on a mythical 240-mile-line between Houston and Dallas, which was chosen to avoid giving the impression that this back-of-the-envelope calculation represents a complete evaluation of any actual proposed route. (The Texas route will be certainly far less attractive than high-speed rail in the Northeast Corridor, but it is not inherently less reasonable than the proposed high-speed rail routes across Missouri or between Dallas and Oklahoma City.)

How big is the reduction in carbon-dioxide emissions associated with switching from cars to rail?

Cars average 22 miles a gallon, and contain an average of 1.63 people. Each gallon of gas is associated with 19.56 pounds of carbon dioxide. That comes to 0.545 pounds of carbon dioxide for each passenger mile, but Iíll increase that by 20 percent to reflect emissions from refining and delivering the gas.

All told, a 240-mile car trip produces 157 pounds of carbon dioxide.

Domestic air flights in the United States average 0.022 gallons of fuel for each passenger mile, and using a gallon of jet fuel is associated with 21.095 pounds of carbon dioxide. Iíll again increase that by 20 percent to reflect refining, and that comes to a total of 133.7 pounds of carbon dioxide on a 240-mile plane trip. This number is close to a Center for Clean Air Study figure based on flying a regional jet.

A classic study pegged high-speed rail in Europe as using from 6.1 to 11.1 kilowatt hours for every 100 passenger miles. The Center for Clear Air Policy also gives electricity use figures for a number of high-speed rail lines that run from 5.6 kilowatt hours for every 100 passenger miles for German intercity trains to 15.6 kilowatt hours for every 100 passenger miles for a Japanese bullet train.

Taking a middle figure of 8.6 kilowatt hours for every 100 passenger miles, and using the North American Electric Reliability Corporation estimate of 1.555 pounds of carbon dioxide for each kilowatt in Texas means 13.37 pounds of carbon dioxide for every 100 passenger miles, or 32.1 pounds of carbon dioxide for a 240-mile trip.

If I assume, relatively arbitrarily, that one-half of the rail riders used to take cars and one-half used to take planes, and that there is no extra travel generated by the rail line, then each 240-mile train trip eliminates 113 pounds of carbon dioxide for each passenger in our atmosphere. These estimates suggest that trains are green, which differs from the studies, which include the emissions from building the rail system, cited by Eric Morris at Freakonomics.

Trains reduce carbon emissions and the world should reduce its carbon footprint, but those two facts donít make the case for rail. Trains make sense only if they are a cost-effective means of reducing carbon in the atmosphere, or whether the social benefit of eliminating 113 pounds of carbon dioxide emissions can outweigh the costs of rail.

A recent review article looked at the dollar cost to the world of each additional ton of carbon dioxide emissions. Most estimates found that a ton of carbon dioxide causes less than $20 worth of damage. Put another way, eliminating a ton of carbon dioxide would bring about $20 worth of benefits. (The one big outlier to these estimates, the Stern Report, shows the benefits of reducing carbon dioxide to be $85 a ton, but that figure has been widely disputed.)

A better way to evaluate the benefit of reducing carbon emissions by rail is to look at the cost of reducing carbon emissions by means other than rail. In current carbon offset markets, the average price of an offset is $7.34 for each ton of carbon dioxide. Technologies like carbon capture and sequestration seem to offer the possibility of reducing emissions for less than $50 a ton of carbon dioxide emissions eliminated.

Iíll assume a environmental benefit of $50 for eliminating a ton of carbon dioxide emissions. With this figure, the total global-warming-related benefit of 1.5 million high-speed riders taken equally from cars and planes is $4.24 million a year.

The National Safety Council estimates the total losses due to traffic accidents in 2008 as $237.2 billion. There were about 3 trillion vehicle miles, and 1.63 people per vehicle, so all this safety cost of cars comes to 4.8 cents a passenger mile (which is more than double more standard estimates). Using this 4.8 cent figure, a rail line that displaces 750,000 drivers creates an extra $8.73 million a year of traffic safety benefit.

A standard estimate is that cars create 5 cents of congestion damage for each vehicle mile of travel. From the same source, Iíll add in another 2.7 cents per vehicle mile to cover local pollution, fuel dependency issues and road maintenance. This works out to another $8.67 million worth of benefits from reducing the number of drivers by 750,000.

Combining reduced carbon emissions, reduced congestion and reduced traffic mortality provides an extra $21.63 million worth of benefits a year from the rail line, which increases the $102 million benefit minus operating costs figure from last week to $124 million, which is still far less than the $648 million estimated cost per year of building and maintaining the infrastructure.

The environmental and mortality benefits of rail are real, but the magnitude of the social benefits from switching modes seems is quite small relative to the cost of the system.

ē ē ē

BLET Editorís Note:

Glaeser's previous columns for the New York Times are here:
July 29, 2009 ó Is high speed rail a good public investment?

August 4, 2009 ó Running the numbers on high-speed trains

Thursday, August 13, 2009

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