BIG PICTURE

Hartsfield-Jackson’s expansion plan includes:

— Modernized terminals and new covered curbside areas, with work now through 2018.

— The Plane Train turnback project, to be done by 2019

— A new Concourse G, in 2023

— Teardown and replacement of larger South and North terminal parking decks, by 2024 and 2027, respectively.

— A new hotel and travel plaza adjacent to main terminal, as soon as 2018.

— Numerous other improvements or additions to runways and taxiways, cargo facilities and support facilities.

Source: Hartsfield-Jackson International Airport

The Atlanta airport is launching a $307 million project that it says will trim wait times for the Plane Train people-mover and add capacity in advance of the train’s eventual extension to new concourses.

The project won’t add any new destinations in the short run but will include a new “turn-back” area that will require construction of a 600-foot tunnel at one end of the line.

The new section will speed turnarounds and cut the intervals between trains by 13 seconds, from 108 seconds now to 95 when the work is done, according to the airport.

Currently, a train arriving at the domestic baggage claim station at the end of the line must wait for any train there to depart before pulling into the station. The new area will create a place for trains to move to after offloading passengers at the end of the line, allowing the next train to come into the station more quickly.

The addition of the turn-back area also will allow 11 more cars to be added to the people-mover system — enabling it to carry more passengers as the airport expands.

In addition to the tunnel, the extension will require evacuation stairways, the airport says. Construction would start in spring 2018 and is expected to be completed in 2019.

The tunnel will go underneath the existing MARTA station and Sky Train station. The SkyTrain is Hartsfield-Jackson’s other people-mover, which goes above ground to the Georgia International Convention Center and the rental car center.

“This isn’t like digging a tunnel underneath normal existing structures,” Hartsfield-Jackson spokesman Reese McCranie said. “We’re talking about lots of complex moving parts,” with other construction projects to occur simultaneously, including construction of an InterContinental hotel next to the terminal.

“There’s a lot of complexity around this project, and this is just one part of it,” McCranie said.

The airport is inviting tunneling contractors to an informational meeting Sept. 20.

The Plane Train project and the hotel are parts of Hartsfield-Jackson’s $6 billion expansion and upgrade plan, which will play out in a raft of projects over many years.

Among the earliest and most obvious will be revamped curbside areas, with overhead coverings added. Longer-term, the airport plans to extend the current alphabet-line of concourses with a new Concourse G. Delta Air Lines, the airport’s biggest tenant, has advocated for two more beyond that.

The billions to fund the expansion will come from the airport itself: a combination of airport funds, the $4.50 passenger facility charge travelers pay on top of air fares, airport bonds backed by airline lease and fee revenue, commercial financing and federal grants.

The airport is owned and operated by the city of Atlanta. By law its revenue cannot be intermingled with general city funds, and it does not draw on city resources to fund expansion projects.