Charleston's flood-prone Crosstown Expressway is one step closer to staying dry.

Mayor Joe Riley announced Friday that the city has lined up $25 million to begin the next phase of drainage work, which will keep construction going after the current work ends in late May.

The S.C. Department of Transportation has approved giving the city $12.5 million in federal funds, and the city will match that sum with $12.5 million of its own money collected from a tax increment finance district around the Gaillard Auditorium. The district siphons off normal property tax income that otherwise would go to the county and school district.

Riley called the news "a significant milestone and substantial progress in achieving the ultimate solution to fixing the flooding on the Crosstown."

The next phase will add new drainage lines and infrastructure under western Spring and Cannon streets, as well as part of Ashley Avenue and President and Fishburne streets.

Unlike the first phase, it should not affect Crosstown traffic, though much of the work will be concentrated along Spring and Cannon streets, where most of the city's fast-food franchises are.

Riley and City Traffic and Transportation Director Hernan Pena said Friday morning's traffic congestion due to the current Crosstown work was better than Thursday's, which wasn't as bad as the city had feared.

With the financing in hand, the city is expected to go out to bids in March for the second phase of work.

The final phases of the $154 million drainage project will be the most costly, and the city is seeking most of that money -- $88 million -- from the State Infrastructure Bank.

The bank is weighing the city's request, and Riley said Friday's news hopefully would encourage the bank's members to support it.

The final phases involve sinking 11 shafts and drilling a new tunnel about 140 feet below the western peninsula; building a wet well that this tunnel would empty into; and building a pump station between the Ashley River drawbridges that would suck the water up and discharge it into the river.

The drainage project will fix flooding in more than the Crosstown. That highway cuts through the middle of one of the city's largest drainage basins, more than 500 acres bordered by the hospital district, The Citadel and the Ashley River bridges.

But it's the Crosstown -- built half a century ago on an old creek bed -- that has been the sore spot.

When a heavy rain falls during a high tide, the six-lane highway can become impassable.

In the recent mayoral campaign, most of Riley's challengers hammered him on the Crosstown's state and why the city has taken so long to fix it.

Riley recently called fixing it the city's highest infrastructure priority.