More than 2,600 flights have been delayed or canceled at San Francisco International Airport since crews began reconstructing a runway on Sept. 7.

But good news if you have travel plans next week: The project is two days ahead of schedule.

SFO announced crews will reach the halfway point and transition on Friday from the first project phase to its second. The repairs on the base layer of the runway are now expected to be finished by Sept. 25, which is two days earlier than anticipated.

The airport is repairing Runway 28L, SFO's second-longest runway, because it showed signs of wear and tear where it intersects with two other runways. This area is the busiest section of the airport's runway system, and more than 68% of flights crossed over it in 2018, according to SFO's website.

Moving More Quickly Than Expected

In the project’s first phase, crews repaired the area where Runway 28L intersects with Runway 1R. Runway 1R will be completed and reopen on Saturday, and crews will transition to working on the intersection of Runway 28L and Runway 1L.

Crews have been working 24 hours a day since the project’s start, according to SFO spokesman Doug Yakel.

The team planned cushion time for the project, anticipating that they would have to reinforce the soil beneath the base layer, which hasn't been excavated for decades. But the soil below is stable.

"We've got a similar contingency in place for the second phase in recognition of the fact that again we're going into an area that really hasn't been touched for about 50 to 60 years," Yakel said.

Phase Two: What to Expect

Runway 1R will reopen for aircraft use on Saturday. This intersection of the runway is larger than the section crews will work on next, so SFO expects improvement in the efficiency of operating runways.

"Keep in mind that this project has always been where 28L intersects with two other runways," Yakel said. "So at any given time at our airport, we've always had two runways closed during this project."

Short-haul flights are expected to be the most impacted, but domestic and international flights may continue to be affected as well.

It's a good idea to check with your airline if you're planning a flight during this time, because most cancellations have been announced in advance, according to Yakel.

"Obviously, there are still some flights that are being canceled on the day of, but upwards of 75 to 80% of all the scheduled reductions happened in advance," Yakel said.

But if possible, SFO still recommends travelers book an early-morning flight before 9 a.m. for the best chance at avoiding long delays.

It also might be a good idea to consider flying out of another major Bay Area airport, such as Oakland or San Jose.

Phase One: A Repair Recap

This isn't the first time SFO has repaired this runway in recent years. In 2017, the airport repaved its entire top layer and discovered problems with the base layer.

After additional investigation, airport staff decided the best solution would be to excavate a 1,900-foot section of the runway. The federally funded project is expected to cost $16.2 million.

As of Thursday afternoon, Flight Aware said 1,970 flights have been delayed and 670 canceled during the project's first six days, and the numbers keep rising.

Flight delays during the first week of reconstruction were also impacted by high winds, according to Yakel. Wind conditions for the next week are expected to improve, but SFO said it still anticipates delays and potential cancellations due to the reconstruction.

The project team stated it selected the original three-week time period of Sept. 7-27 after input from airlines at SFO, hoping to avoid busy summer and holiday travel seasons. The time period also has a low probability for rain, which could affect the asphalt paving.

"For starters there is never a good time to close a runway at such a critical piece of infrastructure for an airport," Yakel said. "There's really never an optimum time. It's usually the lesser of evils."

But some industry analysts are still critical of the chosen time period.

"This is a terrible time for SFO to do this work. It is the start of the business travel season," said Henry Harteveldt, travel industry analyst at Atmosphere Research Group in San Francisco. "I am concerned that there could be a long negative hangover in terms of how people view San Francisco International Airport and San Francisco itself."

KQED's Nina Thorsen and Angela Corral contributed to this report.