FORT LAUDERDALE, Fla. -- A Spanish construction conglomerate has been selected to lead a $1.8 billion project to expand Interstate 595 in Broward County, including adopting new variably-priced, reversible toll lanes that could open in six years.

A state Department of Transportation committee awarded the I-595 project to a team headed by ACS Infrastructores to lead what will likely be the first major public-private highway partnership arrangement in Florida.

If the I-595 contract is executed, the team will be responsible for financing, designing and building the project over a five-year period starting in June 2009, then operate the road until 2044.

Under the proposal, there will be three free travel lanes in each direction, plus a reversible SunPass-only, two-lane tolling area in the center median.

To ease congestion, the two center lanes would operate eastbound in the mornings, providing a straight shot between I-75 to the west and Florida's Turnpike or State Road 7 in the east, then reverse for the afternoon rush hour.

Prices would rise as the express areas become more congested, and drop as traffic gets lighter.

The SunPass-only tolling area would be built in the center median area and operate similar to the soon-to-open express lanes on Interstate 95 in Miami-Dade County. Prices will rise when congestion is heaviest, and drop during off-peak hours.

Based on the bid, ACS Infrastructores will receive 30 annual payments of $63.98 million regardless of the tolls collected after the revamped road opens in 2014.

The second-ranked bidder was seeking a $144.49 million annual payment.

State officials say they are essentially using the private vendor's financing to get the project finished in one-third of the time.

"We're getting it done in five years," said F-DOT project manager Joseph Borello. "If we had to do it the traditional way, it would take us 15 to 20 years."