The millions of passengers who file through airport gates during Thanksgiving week will be accompanied by a holiday baggage barrage.

And no airport will be busier than Hartsfield-Jackson Atlanta International Airport, where more than 1.7 million passengers are expected to pack the terminals during the holiday week — the most since the terror attacks of Sept. 11, 2001.

New security guidelines that limit carry-on liquids have only increased the baggage crush, prompting a 25 percent increase in checked baggage at the airport, said Ben DeCosta, the airport's general manager.

Yet the holiday rush shouldn't lead to a noticeable bump in lost bags if the airport's new automated baggage system stands up to its greatest challenge yet: Handling the busiest week of the year for the world's busiest airport.

The Transportation Security Administration's $170 million system, which began operating in July, replaces a handful of minivan-sized machines that screened bags for explosives on the airport's cluttered hallways.

Checked bags now are sent to a vast underground network of conveyor belts that looks like a complicated game of chutes and ladders. Along that stretch, a handful of explosive detection devices snap X-rays of each piece and alert a bank of TSA screeners in another room to any possible problems.

The screeners decide whether the bags need personal inspection. Those that do are sent to another room, where officers hand search each bag. The system can check about 7,000 bags an hour. The TSA paid $93.5 million of the cost, the Federal Aviation Administration chipped in $39 million while the airport paid the rest, said TSA spokesman Christopher White.

Airport officials say the effort will cut down travel times, particularly when coupled with the airport's newly opened fifth runway. But a Department of Transportation report issued this month told a different story, ranking Hartsfield-Jackson last among other major airports in on-time performance.

The airport's managers said the delays are linked to a repaving project that put one runway out of service this fall. Since the project was completed, DeCosta said delay times have dropped.

"The system has worked like a dream," said DeCosta.

The airport is hoping it continues to run smoothly, as up to 292,000 holiday passengers are projected to move through the airport on a single day this week.

"Not that every other day is practice," said airport spokeswoman Sterling Payne, "but this is our Super Bowl."