Considering that new carpet threw PDX travelers for a loop, the airport's next big plan will be a doozy.

Portland International Airport is planning a five-year, $1.3 billion effort to reinvent the core of its terminal. The rolling construction project will be the first major reworking of the terminal, which has been expanded in piecemeal six times since its construction in 1956.

The plan will need approval from the airlines that operate there, as they ultimately will foot the bill. Port of Portland officials have been working with the carriers to come up with an acceptable vision before they vote on the project in the fall.

If it moves forward, the renovation will be the airport's first chance to catch up with the realities of post-9/11 air travel, which require massive security operations not envisioned when the terminal was built.

And it's also intended to expand the airport's capacity, which is running out after six years of record-setting travel volumes.

"We have made do with what we could until now," said Curtis Robinhold, the newly minted executive director of the Port of Portland. "We're simply running out of capacity to manage the passenger flow we're getting today, and that we'll be getting in the days to come."

If airlines approve the plan this fall, construction would begin in 2020 and continue for five years.

The terminal is one of several major construction projects in the works and includes:

A $215 million expansion of Concourse E and the reshuffling of airlines to make room for more gates.

The construction of a $67 million car wash and fuel station for rental cars.

A $265 million addition to the airport's garage, which will add 2,400 parking spots for rental cars and free up 1,200 stalls for public parking.

The private development of a 7-Eleven gas station and Dutch Bros. Coffee, which is expected to open in August. The development also includes a new cellphone waiting area.

RETHINKING TICKET LOBBY, SECURITY

The terminal redesign aims to improve the flow of crowds through the terminal by minimizing the mixing of arriving and departing passengers.

It also would create more open space in the ticketing area and reduce the size of pre-security concessions, which today's passengers tend to ignore as they make a beeline for security checkpoints.

Last year, the airport saw 18 million travelers come through. The expansion is expected to make room for as many as 35 million a year.

Along the way, the airport will replace aging electrical and plumbing systems, replace the roof, and make structural upgrades to improve the airport's chances of withstanding an earthquake.

Port officials are trying to figure out how to minimize the effect of the overhaul on passengers, and they're looking to the example of Amsterdam Airport Schiphol, which is in the middle of a major expansion.

The plan is to do the work in phases, and to build temporary walls to separate passengers from much of the work.

"It's imperative that we continue to operate as an airport," said Kama Simonds, an airport spokeswoman. "We can't just stop everything today and reopen six months later."

AIRLINE SHUFFLE

Within three years, Southwest Airlines passengers will find their gates at the north end of the terminal.

Southwest is the airport's second-biggest carrier, and it currently shares the south end of the terminal with Alaska Airlines, the largest. Together, they account for more than two-thirds of PDX passengers, and the lopsided arrangement has resulted in bottlenecks for crowds of passengers, baggage and runway use.

An earlier plan to move Alaska was revised after the airline announced it would buy rival carrier Virgin America, and its sister regional carrier, Horizon Air, said it would add 30 Embraer 175 jets to its fleet.

By moving Southwest, port officials hope to ease the strain on operations. The project is already under construction, and Southwest is expected to take up new residence virtually overnight in spring 2020.

MORE PARKING, CONSOLIDATING RENTALS

The expanded parking garage will bring all of the rental-car companies under one roof, just outside the terminal. Some are currently off-site, requiring a shuttle bus.

The short- and long-term parking, meanwhile, is running short even in the off months for travel, Simonds said. Moving rental cars into the expansion area will open more spots for travelers.

"The struggle is real out here, Tuesday evening ... through Thursday, when it comes to parking," she said.

Simonds said demand for rental cars has remained steady, even though the MAX Red Line has served the airport since 2001 and despite the advent of ride-hailing services like Uber and Lyft.

Given the pace at which transportation is changing, however, the port is seeking designs that could repurposed later — for car-sharing services, for example.

Construction on the garage is expected to begin in 2018 and finish in late 2020.

-- Elliot Njus

enjus@oregonian.com

503-294-5034

@enjus