Anyone who has traveled by air recently has undoubtedly experienced plenty of congestion. From the highways that get travelers to the airport, to the parking lots and check-in lines once they arrive, to the narrow seats and jam-packed overhead storage bins on the plane itself—everything can seem crowded.

What harried passengers may not think about are the traffic jams that also occur in the skies above the airport and on its runways. That congestion is less obvious to an everyday traveler, but it can be key to an airport’s efficiency and bottom line, according to Joseph Daniel.

Daniel, associate professor of economics in the Lerner College of Business and Economics, has been researching airport congestion since the early ’90s, ever since he happened to be attending graduate school in Minneapolis at the same time an airport expansion was being planned there. The cost of the expansion, eventually approved at $2.7 billion, got Daniel thinking about ways to increase an airport’s efficiency and, therefore, its capacity.

“Expanding an airport is extremely expensive,” Daniel says. “It can cost almost as much as building a new one. I started to look at traffic patterns and at the congestion that occurs during peak times, when many aircraft are arriving and departing.”

Daniel examined and analyzed “thousands of little green tickets,” which were the control tower’s way of logging in all flights using the Minneapolis-St. Paul airport at the time. He found that flights clustered around certain popular times of day, causing congestion at those times. The resulting graphs he created showed numerous peaks and valleys of flight activity throughout a typical weekday.

“One plane that’s delayed has a ripple effect, beyond the cost of its own landing,” he says. “It also imposes costs—for fuel and wasted time, for example—on the other aircraft using the airport in that same time period.”

If there were a way to more evenly spread out the airplane traffic, smoothing out the sharp spikes and dips on the graph, delays would be reduced, Daniel says. And, he adds, the shift in landing times required to make a noticeable difference in congestion often amounts to mere minutes, not hours.

“You really don’t have to change those peak periods by very much to save a significant amount of time overall,” he says.

A variety of considerations in the complex and highly competitive airline industry prevents airports from simply ordering planes to change their schedules, so Daniel says there must be an economic incentive for the airlines to change. He thinks that can be accomplished by recalculating the landing fees that airports charge, replacing the current system based on a plane’s weight to a new system based on peak demand times. In other words, a plane landing at a peak time period would pay a heftier fee than one willing to alter its schedule and arrive, perhaps, 15 minutes earlier or later.

Ten or 15 minutes may not sound like much, but Daniel notes that travelers often are just passing through a so-called “hub” airport, arriving there only to board a second flight to their ultimate destination. Because passengers want minimal layover times, airlines that are angling for any advantage in competing for customers are reluctant to change their arrival and departure schedules. But, congestion-based landing fees could overcome that resistance, Daniel says.

Daniel has expanded his original research to encompass 28 major U.S. airports and has found that about 15 of them closely follow the congestion model he developed. He believes that some type of fee change, perhaps in the form of a surcharge for peak-demand periods, is inevitable.

“In the 1960s, the government wanted to encourage air travel, so they didn’t want to impose really high fees,” he says. “That may have made sense when you had little congestion, but now that congestion is a real problem, it makes sense to do something different. Those who value the peak time periods enough will pay the higher fees.”

By spreading out the air traffic to reduce congestion, he says, a typical airport could become 30 percent more efficient and able to handle more planes without building expensive new runways, gates or terminals.

Daniel’s research has applications to highway congestion, as well. He and then-graduate student Khalid Bekka, BE ’98PhD, published an article in the Journal of Urban Economics in 1999 that analyzed traffic patterns on major roadways in northern Delaware. They concluded that some type of electronic toll system on the most congested highways, such as I-95 through the city of Wilmington, could encourage drivers to use alternate and underutilized routes, such as I-495 that loops around Wilmington. As with airports, the result would be that traffic would spread out more evenly and reduce congestion.

—Ann Manser, AS ’73