A dreaded perfect storm of the summer season hit Dulles International Airport this week as travelers returned to the sky in record numbers, a new airline began service and the checkpoints were shortstaffed, creating security lines that snaked the length of the terminal and back again.

Travelers said that in some cases they waited in lines lasting up to an hour. Recent airport construction, which relocated many of the security lanes, also befuddled travelers. The airport has reconfigured its security checkpoint into a maze of switchback lanes that looked more elaborate than any line at Disney World. And the airport hired a team of college students, armed with walkie-talkies, to supervise the lines and inform people of the likely duration of their wait, depending on their distance from the screening site.

"We just try to keep some order," said Theresa Anne Branigin, a 19-year-old college student, who was sweaty and tired at the end of her shift on Thursday. She had taken to carrying a bottle of water to soothe her throat. "We were shouting ourselves hoarse yesterday."

Airlines and airports have been bracing for the summer travel season, and Dulles security lines are going to be hardest hit. Airlines say travelers are buying tickets in record numbers, apparently an effect of the rebounding economy, and Dulles's new low-fare carrier, Independence Air, expects to add 300 daily flights in coming months. At the same time, airlines say Dulles's security checkpoint lanes are short of staff and not all lanes are open to accommodate travelers.

On busy days, such as Mondays and Fridays, and during certain times of the day, such as between 6 a.m. and 8 a.m. and between 3 p.m. to 5 p.m., some passengers have waited 45 minutes to an hour in security lines. Travelers may experience longer-than-usual delays at the checkpoints this summer at Washington's Baltimore-Washington International and Reagan National airports, but spokesmen for those airports said the waits are not reaching beyond 20 minutes.

"Our biggest concern is the next two to three weeks," said Richard P. DeiTos Jr., executive director of the Metropolitan Washington Airlines Committee, a group that represents airlines serving Dulles. "That's when there will be the most increase for additional airline service and the staffing [at the checkpoints] will not be there."

The Transportation Security Administration said it just hired 130 security screeners at Dulles, which has been operating with too few screeners for many months. The agency has had difficulty recruiting screeners there because no public transportation is available in the early morning and late evening to accommodate the workers' shifts.

Mark Hatfield, a TSA spokesman, said the screeners are being trained and undergoing background checks and will arrive at work in mid-July. "The addition of Independence Air was being factored in the decision for new hires," Hatfield said. "When you add 300 flights a day to an airport, you've got to do some serious addition to your capacity in order to take it."

Members of Congress and airlines have criticized the TSA for the long lines that started to appear at a number of major airports, including Dulles, several months ago. But airports say the agency has made improvements.

"It affects everybody -- passengers, crews, even airline CEOs and members of Congress," said Doug Wills, spokesman for the lobbying group Air Transport Association. "They call TSA or call the airlines and say, 'Can you get us through quicker?'"

At Atlanta's Hartsfield International Airport, where security lines are longest, passengers have waited more than an hour to go through checkpoints this week. The TSA has added staff there and is knocking down retail stores in order to make the checkpoint larger. In Las Vegas, where last winter some passengers waited as long as four hours to get through security when a large convention was in town, the airport now reports that lines have shortened .

"The lines have gotten better -- it's really good now," said Elaine Sanchez, spokeswoman for Las Vegas's McCarran International Airport.

At Dulles, lines that are clogged during the rush hours move remarkably fast at other times. On Thursday, just 30 minutes after the rush hour, passengers trickled through the security gates and the airport's team of line managers were suddenly without work.

Megan F. Steiner stood near the checkpoint holding a yellow happy-face balloon on a long string. She used the balloon to show passengers where the line ended.

Other workers agreed that their job became easier if they were able to lighten the mood among disgruntled passengers who sometimes yelled at them in protest of the waits. Larry Franklin, 19, said he did jumping jacks to entertain the crowd. Eric Siriprakron said he told jokes. Steiner said she simply held the balloon. "I told them they could not get in line unless they smiled."

Independence Air employee Swan Luong, left, receives her boarding pass from fellow employee Adam Long in Dulles International Airport. Independence Air passengers will add to the airport's congested security lines.