Charleston International Airport has a long way to go in its $189 million terminal overhaul, but the word "completion" is starting to be used, at least for part of the extensive makeover.

On Wednesday, the new rental car pavilion is set to open in a 6,200-square-foot addition on the left side of the passenger building.

Rental-car companies will move their equipment over Tuesday night, and hopefully set up for operations for travelers by first thing Wednesday morning, according to Matt McCoy, who is overseeing redevelopment of the 29-year-old terminal as program manager for Michael Baker Inc.

Also, the state's busiest airport recently opened a third baggage carousel. The original two will be dismantled and replaced. The first of those two is walled off from passengers for now, but its replacement is running ahead of schedule and should be spinning around luggage by month's end, McCoy said.

Because of all the torn-up concrete and ongoing construction of new electrical lines and pipes in some of the areas where airlines park near the concourse gates, the airport is desperately trying to reclaim some of the space.

"If we can see some of the real estate coming back, it will be a huge step forward," airports director Paul Campbell said.

On Concourse B, where five new gates are being added to handle an anticipated surge in airline traffic over the next decade, steel framing is starting to rise, a sign that base work is complete.

Over near Concourse A behind the airline ticket counters, an area that will house consolidated security checkpoints downstairs and airport offices upstairs, vertical construction hasn't started yet.

And the central hall, the former huge open space in the center of the airport, is walled off with huge swaths of canvas draping the inside to collect rainwater in a floor drain. Part of the roof will be replaced with a dome when the project is completed in August 2015.

"We are going to end up with a great airport terminal when this is all over," Campbell said. "We just have a lot more ahead of us."

Reach Warren L. Wise at 937-5524.