Travelers are closer to getting free Wi-Fi at the world’s busiest airport.

Hartsfield-Jackson International Airport plans to seek approval for a wireless Internet infrastructure upgrade contract that will pave the way for free Wi-Fi.

If the measure is approved by the Atlanta City Council in the next week, the best-case scenario is that free Wi-Fi could be ready to launch by the end of March, Hartsfield-Jackson spokesman Reese McCranie said. “We’ve heard loud and clear that (the lack of free Wi-Fi) is an issue with passengers and we are aggressively seeking a solution,” he said.

Once it’s ready, the airport will be able to support as many as 15,000 Wi-Fi users at once. Currently only 4,000 can get on the paid Wi-Fi system. Hartsfield-Jackson serves as many as 250,000 passengers a day.

The upgrade of the airport’s outdated Wi-Fi infrastructure could cost nearly $6 million, according to documents from the airport. Johnson Controls Inc. was selected to do the work as the lowest bidder at $3.6 million. But the airport is budgeting as much as $6 million, mainly to include an incentive for the work to be completed more quickly.

Free airport Wi-Fi long has been among the most requested amenities at Hartsfield-Jackson. The Atlanta airport is like a crossroads for travelers, who often want to check the Internet and their email for updates, said traveler Cardell Smart, who lives in Ellenwood. “There are other airports that have free Wi-Fi that are not this big.”

Many other airports around the country already offer free Wi-Fi, including Boston, Dallas and Fort Lauderdale.

The current Wi-Fi system at the Atlanta airport was installed in 2005, and since then Wi-Fi technology has significantly improved.

In 2012, the airport took over its Wi-Fi service from independent wireless Internet service providers, lowered the price for Wi-Fi access to $4.95, and announced a plan to launch free Wi-Fi by fall 2013.

But fall 2013 came and went with no free Wi-Fi at the airport. That’s because in the first round of bidding, both companies that submitted bids were turned down because of incorrect forms or because they were not qualified. The airport rebid the contract, which led to the selection of Johnson Controls.

The initiative to provide free Wi-Fi at Hartsfield-Jackson came from Atlanta Mayor Kasim Reed, according to airport officials.

Separately, frequent travelers who are willing to pay a fee to avoid some of the hassles at security checkpoints can now apply at Hartsfield-Jackson to join a Transportation Security Administration trusted-traveler program.

Joining the PreCheck program allows travelers the opportunity to keep their shoes, jacket and belt on, and keep their laptop and bag of liquids in their carry-on luggage.

The TSA has opened an application center at the Atlanta airport on Concourse A. The location is past security, between Gates A19 and A21.

TSA launched the PreCheck program on a narrow basis in 2011 by partnering with airlines, which offered the program to their most frequent fliers.

But last year, TSA announced plans to broaden the program significantly, and started taking applications from those interested in December.

Travelers must visit an application center to provide fingerprints and valid ID and documentation — and pay an $85 application fee.

Atlanta joins other airports that already had PreCheck application centers, including in Los Angeles, New York, Washington and Indianapolis. TSA plans eventually to expand to more than 300 application centers nationally.