More than 1.6 million passengers are expected to pass through Hartsfield-Jackson International Airport over the long Memorial Day weekend, kicking off the busy summer travel season.

Hartsfield-Jackson forecasts weekend traffic over the holiday travel period running from Thursday through Tuesday will be up 3 percent this year compared with 2012.

Passenger traffic has varied so far this year, but “I think we’re seeing the economy is improving,” Miller said. During heavy traffic periods, “it’s going to be extremely busy.”

But nationally, AAA Travel said it expects Memorial Day air travel to be down, while travel by automobile will be up. The auto club said in Georgia about 1 million people will travel for the holiday, with about 9 out of 10 going by car.

Meanwhile, national airline industry group Airlines for America said it expects travel on U.S. airlines for the full summer to be up 1 percent from 2012, with a record number of international passengers. The group said the busiest air travel days are Thursdays and Fridays from mid-June through early August.

Airport officials recommend travelers get to the airport 90 minutes before a domestic flight and two hours before international flights. The airport has a domestic terminal off I-85 and an international terminal off I-75.

Road work is going on at the domestic terminal, and security lines have been longer than 20 minutes at times in the last few weeks, though Hartsfield-Jackson general manager Louis Miller said there have been some improvements since then.

New concessions are opening in the domestic terminal, including a TGI Friday’s. Miller also said the airport’s year-old international terminal will next month get a long-planned common-use lounge, an upscale option open to travelers on any airline for a fee.