WASHINGTON ( TheStreet) -- As the airline industry continues to coalesce around its hub airports, those hub airports continue to expand, spending billions of dollars to upgrade facilities.
A survey by Norcross, Ga.-based Reed Construction Data listed the top five airport construction projects of 2014. Each involves more than a billion dollars in spending or, in some cases, in contract awards for future spending.
The biggest project this year is the $5.6 billion, 23-mile extension of the Washington D.C. Metrorail system to Dulles International Airport. When completed, the new Silver Line will offer direct "one-seat" transportation from downtown Washington to the airport.
Top projects also include expansion at LAX, Dallas-Fort Worth, Denver and Salt Lake City, the survey showed. Dulles and Denver are hubs for United (UAL - Get Report). Salt Lake City is a hub for Delta (DAL) and Dallas-Fort Worth is a hub for American (AAL - Get Report).
Big airport projects are important for four reasons, said Bernie Markstein, U.S. chief economist for Reed Construction Data.
"First, when they are an expansion of landing spots/available gates, which most large projects include, they represent a response to demand for air travel to that city," Markstein said. "This is an indication of an expanding, vibrant local economy."
Secondly, when airport expansion enables more flights, "it helps attract more companies and tourists since it is easier for people to travel to and from that location," Markstein said.
In particular, American CEO Doug Parker has said that hub growth creates a "virtuous circle." During a 2013 visit to Charlotte, Parker said that when US Airways offers more flights in Charlotte -- currently it has 645 daily departures -- "the business community can attract more and more companies, and once more companies come, we can (offer) more flights."
Markstein said airport projects also enhance construction spending, which much of the money flowing directly to the community as "workers spend their wages and local companies are paid for building materials." Additionally, he said, "Even if the project doesn't expand the size of the airport, having a modern, architecturally beautiful airport with efficient means of moving people, their luggage, and packages has a big impact on the impression that city makes on various people from business travelers to tourists.
"The airport is often the first impression a traveler has of a city -- and you know what your mother told you about first impressions," he said.