At least six years of extra congestion and delays on Interstate 4 begin Sunday in Orange and Seminole counties.

The I-4 Mobility Partners officially took charge of the I-4 Ultimate Improvement Project makeover at midnight Sunday, and the clock is ticking on a $2.3 billion overhaul through the heart of Central Florida.

Although the project is underway, drivers probably will not notice any significant backups along the 21-mile stretch until later this month. The peak of the project is expected in 1-2 years, when there will be about 2,000 workers.

Work will impact anyone trying to navigate Kirkman Road, east through downtown Orlando, to State Road 434.

Downtown driving is where motorists will really feel the project's effects. The interchange with State Road 408 will be redone and take at least three years to complete.

"There are going to be impacts to people's commutes," said Steve Olson, a spokesman for the Florida Department of Transportation. "There may be impacts to those along the corridor that count of those commuters. But, you know, as a community and as a region, this is something that we're going to have to work through for the next few years."

I-4 will never be completely shutdown throughout the project, though.

"You cannot close an interstate like I-4 totally to do the construction," Olson said. "That would create so much confusion. I mean, this is a vital artery."

Once it's all said and done, it will make driving along I-4 much simpler and more aesthetically pleasing. Motorists will have more lanes to use from Kirkman Road, in Orange County, to State Road 434, in Seminole County. The project also includes new toll lanes, also called express lanes.

The Florida Department of Transportation hasn't determined the toll cost, but officials said it will vary based on traffic volume and demand.

The project is expected to hire thousands of workers.

The state is urging drivers to consider options and use alternate ways as the project progresses.