In the United States, getting between the airport and downtown can sometimes be the most irritating part of a trip.
But when DART Rail Orange Line trains begin serving Dallas/Fort Worth International Airport later this year, Dallas will join Seattle, Washington, D.C., San Francisco, Chicago, Atlanta and an increasing number of other cities with rail links that make it easy for business and leisure travelers— and airport employees—to make that journey.
"The vast majority of public transport to airports is by buses," said Deborah McElroy, executive vice president for policy and external affairs at Airports Council International-North America. "But airports are increasingly recognizing that rail transportation is favorably viewed by passengers; especially those from other countries where rail to the airport is more common."
In April 2013, the Utah Transit Authority opened Airport TRAX, a six-mile light-rail line to Salt Lake City International Airport. That was the same month Phoenix Sky Harbor International Airport's Sky Train began service between Terminal 4 (the airport's busiest terminal), and Valley Metro Light Rail. The free system will eventually make stops at the airport's other terminals, but has already carried 3 million passengers, said Heather Lissner, PHX airport spokeswoman.
In addition to making it easy for travelers to get to and from the airport, Lissner says locals have been taking the Sky Train to the airport on dates. "People park in East Economy or ride the light rail to connect with the PHX Sky Train then enjoy dinner in Terminal 4 at one of our pre-security restaurants and look at the various art exhibitions in the terminal," she said.
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At Miami International Airport, a 2.4 mile Metrorail extension opened in 2012, and the airport's Central Station should be complete by the end of 2014, adding links to Amtrak and the region's Tri-Rail service.
By the end of 2014 the 3.2-mile, $484 million Oakland Airport Connector—a people mover linking the airport to the Coliseum/Oakland Airport BART Station—is scheduled to open as well.
"We already have regular bus service between OAK and the BART station," said Oakland International Airport spokesman Scott Winter, "but the new line will add a new level of convenience and, most importantly, reliability, as it cruises above traffic below."
A rail link to an airport is not just convenient; according to a joint study released in November 2013 by the U.S. Travel Association and the nonprofit American Public Transportation Association (APTA), which advocates for public transportation. (APTA dates to 1882, and its initial meetings focused on the price of oats for the horses that pulled transit vehicles.) "Rail cities" can have a financial edge, the report contended.
"We found that cities with airport rail connections have a competitive advantage in generating revenues for the private sector and the overall city tax base compared to similar cities that do not have direct rail connection to the airport," Darnell Grisby, APTA's director of research and policy, told CNBC.
The study compared hotel performance in six cities with airport rail service—Atlanta, Chicago, Washington, D.C., Minneapolis, Portland, Ore., and San Francisco—to hotel performance in popular convention cities without direct airport rail service—Las Vegas, New Orleans, Orlando, Fla., Sacramento, Calif., and Tampa, Fla.
Hotels in rail cities were found to receive nearly 11 percent more revenue per room than hotels in cities without an airport rail connection. According to the study, that higher revenue per room translates to a potential $313 million in revenue per year for the rail cities.
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While cost and other concerns can be a deterrent, building a rail line to an airport can be an economic generator that makes a city more appealing to meeting, event and convention planners, said Erik Hansen, senior director of domestic policy at the U.S. Travel Association.
"The decisions of these planners can generate millions of dollars in spending at hotels and local restaurants," said Hansen. "And if they're going to put anywhere from 1,000 to upwards of 25,000 people on the road at a single time and have them leave an airport at a single time, they want transportation options."
With some of those issues certainly in mind, the Metropolitan Washington Airports Authority is moving ahead with a two-phase plan for improved rail service to Dulles International Airport that includes constructing a 23-mile extension of the existing Metrorail system.
Denver International Airport has partnered with the Regional Transportation District to add a 22.8-mile commuter rail connection from DEN to downtown Denver that is scheduled to open in 2016.
In Los Angeles, studies are underway to decide how best to connect the Metro Rail system with Los Angeles International Airport. And Orlando International Airport has announced plans to spend $470 million to build an automated people-mover system to support a variety of future travel connections, including intercity rail service between Orlando, Miami and the airport.
The people mover planned for Tampa International Airport may someday link to a regional transportation center and there's promise of a mass transit link as part of New York City's LaGuardia Airport Central Terminal overhaul.
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"It certainly depends on the airport community and who they are competing with," said McElroy of ACI-NA, "but a number of airports have indicated that they believe having a rail link from the airport to downtown is a key factor in being competitive in the global airport market."
—By Harriet Baskas, special to CNBC.com. Baskas is the author of seven books, including "Hidden Treasures: What Museums Can't or Won't Show You," and the Stuck at the Airport blog. Follow her on Twitter at @hbaskas. Follow Road Warrior at @CNBCtravel.