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Buzz is building around electric and autonomous vehicles as advances from companies like Tesla push the technologies further into mainstream consumer spaces. While the US has not yet reached a tipping point in widespread adoption of sustainable transportation, the industry is rapidly building toward the breakthroughs needed to make sustainable options affordable and flexible enough to shift consumer habits.

David ClarkeIn a number of UT departments, researchers are focused on this next generation of transportation advances. The Center for Transportation Research, housed in the Tickle College of Engineering, is engaged in research and education that seeks to improve the nation’s transportation infrastructure and inspire students to help solve tomorrow’s transportation problems.

David Clarke, director of the center and a research associate professor in the Department of Civil and Environmental Engineering, specializes in railways, freight systems, and transportation planning and safety. He says that when we think about sustainable transportation, we can look to railways for a path forward.

How is the freight rail system a model of sustainability?

Traditional freight rail is pretty sustainable. In the 150 years since its creation, the railroad industry has proved itself to be adaptable and very efficient in making transitions to changing technology. At its beginning, railroad locomotives burned wood to generate steam; today, many railway systems are powered by electricity produced centrally and distributed along the track. That energy can be generated a number of ways—by wind, solar, and nuclear energy. As with motor vehicles, battery and hybrid technologies are also emerging.

The railway system is easily powered and very energy efficient, especially compared to highway transportation. Many Americans have little personal experience with rail transportation because of our highway-centered mobility, so the concept of sustainable railways is not widespread. In contrast, railroads—including electrified urban transit rail and high-speed intercity rail systems—are an integral part of sustainable mobility in many other countries. Rail freight is also expanding as an option to reduce environmental impact and highway congestion.

Railroads must be sustainable from a business standpoint. Freight railroads are private companies that must finance infrastructure and equipment and generate profits for shareholders. Despite intense competition from pipelines, barges, and trucks, freight railroad companies remain remarkably good investments. America’s first transcontinental railroad company, Union Pacific, will celebrate its 150th anniversary in 2019.

Are passenger rail systems a path to sustainability?

Passenger railroads are very different from freight in that they are often publicly owned. In major cities with highway congestion problems, passenger rail is very popular; cities can’t easily build their way out of highway congestion. Keeping fares affordable, however, means that most systems do not make enough money to offset the costs of construction, maintenance, and operation. Their sustainability comes from social willingness to offset deficits using various forms of public funding.

Our county is automobile focused, primarily due to easy mobility and convenience. Billions of taxpayer dollars are invested in construction and peripheral services related to our roadway network. Our citizens do not accurately feel the cost of automobile use because of public subsidies.

What could we see from rail advances in the future?

While the future power source for railroads in a post-petroleum era is likely to feature electricity, there may be a future for steam locomotion. New locomotive designs using natural gas to boil water into steam that propels a turbine generator might be a viable option. Concerns about high energy prices in past years have generated proposals for modern steam-based propulsion, but as petroleum prices dropped so did interest. If there is another energy crisis, this idea could surface again.

The maglev—a system that uses magnetic fields to lift the train and propel it forward at very high speeds without moving parts—is exciting, but the cost is high compared with that of a traditional railroad. Extensive production of maglev lines could capture a major portion of the world’s supply of nickel, copper, and cobalt, dramatically driving up prices of these materials in other markets, like construction.

How do railways stack up to automobile and air travel in alternative technology advances?

The automobile industry faces some interesting challenges. Electric vehicles are great for commuters, but the range of the current battery power is limited and recharging can take hours. It’s not practical to take a trip in an EV without building in time for charging. Electric vehicles need to approach the range of gasoline-powered vehicles and be quickly rechargeable for widespread adoption of the technology. The same is true of autonomous vehicles. Despite advances, we’re a long way from having an affordable car that can perform at the level of a human driver.

Additionally, the components of alternative technologies face their own supply and demand issues. The supply of lithium for batteries, for example, is finite, and most suppliers are not in stable parts of the world. Batteries of all sorts are in demand across new technologies, and those supplies are getting stretched further and further.

The airline industry, in contrast, is completely dependent on petroleum. If oil prices peak, air travel costs go through the roof.


Karen Dunlap (865-974-8674,