Lines were long at Minneapolis-St. Paul International Airport before 6 a.m. Monday, regardless of whether people were headed to the north or south security checkpoint. (The Minnesota Star Tribune)

What exactly is up with the airport — besides wait times at the security checkpoints?

A $1.6 billion renovation at Minneapolis-St. Paul International promises to increase the number of checkpoint lanes, expand the ticketing and baggage area and better connect the lower and upper levels. But as fliers discovered on a busy Monday at Terminal 1 (Lindbergh), there will be pain before the gain.

Here are five things to know before heading to MSP this fall.

1. Work at the south checkpoint will limit its operations through the fall. It is now open only to fliers with TSA PreCheck and Clear with PreCheck. Other travelers, including first-class, Delta Sky Priority and Clear passengers who lack PreCheck, should use the north checkpoint, which has 10 operable lanes. A skyway-level checkpoint has been closed due to TSA staffing reductions. But one for those with only carry-on luggage is available on the third floor of the Intercontinental MSP Airport Hotel, linked to the airport by skyway at Concourse C. Fliers could get dropped at the hotel, park in the ramp near the hotel or shuttle to the hotel from the airport. The checkpoint is open from 5:15 a.m. to 10 a.m.

2. Earlier the Metropolitan Airports Commission's recommended arrival time was unchanged: two hours for domestic flights, three for international. But on Friday, Delta recommended upping that to three hours for domestic.

3. MSPairport.com, the MAC website, typically shows wait times at checkpoints in both Terminal 1 and 2. Ironically, just as construction makes that information more vital, that very work has disrupted the service. The automated system uses cameras to gauge the passenger queue; construction material is currently covering those cameras. The MAC hopes to have the system operational by mid-October, but also notes that wait times can change dramatically between the time someone leaves their home and arrives at the airport.

4. Since last week, MAC has added staff to help direct passengers in the ticketing area, and TSA has agreed to fully staff all current lanes (10 at the north checkpoint; six at the south) beginning at 5 a.m.

5. Brace yourselves. The current improvement project, dubbed Reimagine MSP, will be completed in 2023. But the MAC is already at work on long-range plans through 2040 — and it could include construction.

Correction: A previous version had the incorrect hours of the TSA security checkpoint at Intercontinental MSP Airport Hotel.