RIVERVIEW — County commissioners have approved a long-awaited development agreement that will pave the way for the widening of U.S. 301.

But officials are still waiting for some developers to pay part of their $15-million share of the $111-million project.

The county must give $57-million to the Florida Department of Transportation by April 30.

"It won't be done until it's done," said Mike Merrill, Hillsborough County's debt management director. "We're all working hard to get there."

A unique public-private partnership between the county, the state and developers will fund the 6.1-mile expansion, which will widen the road from two to six lanes between Gibsonton Drive and County Road 672.

After 10 developers pledged to contribute $39.7-million in March 2005, officials hoped construction crews would break ground in early 2007. They began negotiating a deal with another group of developers to contribute more.

But the real estate market cooled, road construction costs grew and some of those developers dropped out. For a few years, attorneys, officials and developers have struggled to nail down a deal.

County commissioners finally approved it last month. Twelve developers agreed to contribute about $15-million more.

Grant funding will pay for about $47-million of the project's costs.

Despite delays, officials said they're happy to see the project moving forward.

"It's taken longer, but I think we've found a way that benefits everyone in the county," Merrill said.

County commissioners praised the project at last month's meeting.

"Being creative and working with the builders so that we can have these improvements, it's very important," Commissioner Mark Sharpe said.

Catherine E. Shoichet can be reached at cshoichet@sptimes.com or 661-2454.