Getting There Greener: Frequently Asked Questions

What is the greenest way to travel?

Generally speaking, motor coaches (inter-city buses) are the greenest mode of vacation travel. Beyond motor coaches, the greenest way to travel depends on how far you are traveling and how many people are traveling with you.

How can I figure out the greenest way to travel from a particular location?

Google Maps, airline booking sites and other Internet tools can help you figure out exactly how far your chosen destination is from your home. Tables in the report appendix assess trip emissions for eight discrete mileage distances ranging from 100 to 3,000 miles and include emission factors that can be used to calculate trip emissions associated with any travel distance.

How did UCS reach its conclusions?

UCS's findings are based on energy consumption, ridership, and carbon dioxide emissions data from a number of government and commercial sources. Using that data, UCS researchers calculated how much carbon dioxide pollution a given mode of travel produces per passenger for each mile traveled.

What about other pollutants besides carbon dioxide?

The intent of this report is to assess the comparative carbon impact of various modes of travel. While these transportation modes emit other pollutants that harm the environment, a lack of comprehensive data prevented them from being included in this analysis.

Why does flying first class generate more pollution than economy class?

In order to provide an "apples-to-apples" comparison of air travel emissions, UCS evaluated passenger data on the basis of " economy-equivalent seating," a value that reflects the amount of cabin space occupied by an economy class seat. Since first-class seats occupy approximately twice as much cabin space as an economy-equivalent seat, passengers flying in them are effectively responsible for twice the emissions of an economy class passenger. Airlines that have coach-only seating can transport more passengers on a given amount of fuel, resulting in lower per-passenger carbon emissions.

Does it matter what kind of airplane you fly on?

Yes. Airplanes can vary widely in the amount of pollution they generate per person per mile traveled. UCS's recommendations are based on the types of airplanes typically used for trips of a given distance. For instance, turbo-prop airplanes are typically used for flight distances of 100 to 250 miles while wide-body jets are used for flights of more than 2,000 miles. Travelers who want to compare and contrast airplane types should consult Appendix B in the full report at www.ucsusa.org/gettingtheregreener. Travel Web sites also often offer specific information about plane models.

If a train, bus or plane is scheduled to travel somewhere anyway, how can you say that any one passenger is responsible for emitting pollution?

We developed and used average emission factors for this report, largely out of necessity. The data used in the analysis were largely in aggregate form and thus we were unable to assess whether or not an additional passenger on a given mode of transportation would cause an operator to put another train, bus or plane into service. Even if such data were available, it would yield highly variable and sometimes extreme results that would provide very little practical information to the typical vacation traveler. While consumers currently might enjoy a carbon "free ride" on low-occupancy vehicles, such as motor coaches or trains, they are less likely on airplanes, where capacity is tightly linked with demand. For more information on this topic, see Appendix A in the full report.

Can this report help me plan a green vacation outside the United States?

"Getting There Greener" applies solely to domestic travel. Transportation options and emission factors vary from country to country, and thus the report results do not apply globally. That said, the report's general guidelines for decreasing emissions from driving (improving fuel economy) and flights (taking direct flights, flying economy) would apply anywhere. Avoiding travel during peak congestion periods also would reduce your pollution contribution no matter where you are.

Can this report help me pick the greenest commuting option?

The report applies only to a one-time trip of more than 100 miles. Scoring methods of commuting would involve similar calculations, but might lead to very different results. Commuting is also highly dependent on local roads, traffic patterns and transit options.

What about walking or bicycling?

While not covered in our report, walking and bicycling are also excellent low- or even zero-carbon options for vacation travel. In fact, regardless of how you reach your vacation destination, these modes can be the greenest ways to move around the community once you arrive.

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