The William Penn Foundation has committed to helping raise the final $10 million needed for a $225 million development initiative along the Delaware River that includes capping a portion of I-95 between Chestnut and Walnut Streets with a four-acre park.

The development along the central Philadelphia riverfront, to be spearheaded by the nonprofit Delaware River Waterfront Corp., also is to include construction of a two-mile bike trail along Columbus Boulevard and extension of the South Street Bridge to Penn's Landing.

With the pledge, construction is on track to begin in 2019, with work expected to last three years, officials said at a Friday news conference atop a Penn's Landing parking structure overlooking the section of highway that would be capped.

"We are confident that together, we can close the gap soon," foundation board chair Janet Haas said, vowing to collaborate closely on fund-raising with city and state officials as well as the waterfront corporation.

The waterfront corporation already has been the beneficiary of $15 million in funding for projects such as the landscaped Race Street Pier that are thought to be encouraging private investment along the waterfront.

Plans for the cap were mentioned by New York's Durst Organization as a factor driving its acquisition in March of four piers just north of the Benjamin Franklin Bridge for later development.

The cap and related projects were first proposed during the Nutter administration, and received a boost in February when Mayor Kenney proposed budgeting $90 million for them. State officials allocated an additional $110 million for the initiative, with the foundation chipping in $15 million.

Gov. Wolf said Friday that the park, which will slope toward Penn's Landing, and the extended South Street pedestrian bridge will reconnect Center City with the Delaware River waterfront, which was cleaved from the city by I-95.

"I know what a dividing line this is for the city," Wolf said of the highway. The project "is going to be a big step forward, and a big step away from what happened in this area with the development of that dividing line."

The protected bike lane will begin at Spring Garden Street, connecting with a section of trail that dips behind SugarHouse Casino, and continue to Washington Avenue in South Philadelphia, where it will link to a path along the river behind the Sheet Metal Workers Local 19 union hall.