This summer's outbreak of lost bags, flight delays, packed planes and long lines is taking a toll on U.S. travelers.

More than 50 percent of people who have taken a trip recently expressed some level of frustration with airline or airport service, according to a survey released Tuesday measuring the biggest travel hassles.

One in three respondents said they were "very frustrated" with flying, and airline-related concerns ranked as the second-largest irritant behind gas prices.

"Pretty much everybody it seems is experiencing some level of pain with air travel, whether it's not getting served food on flights, dealing with long lines or going through security at the airport," said Mark Cipolletti, spokesman for the travel insurance firm Access America, which commissioned the study. "It's become a major frustration."

The survey, conducted by global research firm Ipsos Public Affairs, included responses from more than 1,000 adults who traveled in the past three months. The results were used to create a Traveler Frustration Index, which will be updated on a quarterly basis.

It's no surprise that air travel ranks as one of the worst offenders.

Airlines have struggled this summer to cope with record demand for air travel. After cutting back on staff for years, carriers have fewer workers to handle the influx of passengers. They also are packing more people on each flight, meaning that there is little wiggle room to accommodate unexpected problems such as bad weather or mechanical delays.

"I'm just amazed that it is only half," said Joe Brancatelli, an industry expert who runs a Web site for business travelers. "When you have one in three chances of being late, one person per flight is losing luggage, the in-flight service is bad, the fees are piling up, how can you have a good experience?"

Aside from gas prices and airline service, U.S. consumers seem largely content overall with the state of travel. The Traveler Frustration Index - which represents a weighted average of survey responses - came in at 4.1 on a 10-point scale, meaning that travelers haven't come close to reaching the boiling point.

Top travel irritants

Percentage of respondents who expressed some level of frustration:

• Cost of gas   78 percent

• Airline/airport service   54 percent

• Cost of airline, cruise line or train tickets   48 percent

• Cost of lodging and/or other attractions   44 percent

• Homeland security/ safety issues   38 percentSource: Traveler Frustration Index

walshc@RockyMountainNews.com or 303-954-2744