By 2015, a $3 million ramp for bikers and walkers is expected to be under construction on the Camden end of the Ben Franklin Bridge.
All told, about 285 miles of trails in the network are now built, and 50 more are in development, leaving about 415 miles to go.
Trail advocates hope to complete the network within 20 years at a cost of $250 million.
The push for local trails, led by a coalition of nonprofit organizations, coincides with a national drive to create a 3,000-mile East Coast greenway from Calais, Maine, to Key West, Fla. Segments have been completed to make up about 29 percent of that trail.
"We're doing it inch by inch, step by step," State Sen. Michael Stack (D., Phila.) said as he helped celebrate the opening of the Port Richmond Trail last week. "It's taking us a little longer than we would like . . . but we look forward to moving it forward."
Cyclists and walkers, long ignored in favor of cars, industries, and suburban development, have prodded local and state officials to develop trails for recreation, commuting, and travel.
Since 2010, local trail advocates have gotten a big financial boost, with $28 million in federal grants and $10 million from the William Penn Foundation for dozens of trail projects in the nine-county region.
A newly formed Circuit Coalition of 31 nonprofit organizations announced last year a campaign to "connect the circuit" by tying disparate segments together into a complete network of trails.
"When complete, the circuit will be one of the signature features of Greater Philadelphia, the nation's finest trail network, providing non-motorized access from the Appalachian Trail to the Atlantic Ocean," Jeremy Nowak, then-president of the William Penn Foundation, said at the time.
Early next year, coalition leaders plan to ask the board of the Delaware Valley Regional Planning Commission to earmark money for three more years of trail construction and planning.
The DVRPC, which oversees transportation planning and funding for the region, managed the $10 million donated by the William Penn Foundation as a regional trails fund for about 35 miles of trails.
The Circuit Coalition will ask for $10 million more in federal and state money to replenish the fund for the next three years, said Sarah Clark Stuart, policy director of the Bicycle Coalition of Greater Philadelphia, one of the steering members of the trail group.
"We want to make sure things keep moving and fill the gaps where they exist," Stuart said.
In Philadelphia, one of the goals is to make the city's two rivers more accessible to residents.
"The reason we're not a great river city is something called I-95," said Robert Borski, the former Philadelphia congressman who chairs the Delaware River City Corp., which is promoting a riverfront corridor in Northeast Philadelphia. "It took the river away from us."
Although many stretches of waterfront remain blocked by highways, industries, and railroads, several new pocket parks - like the Race Street Pier below the Ben Franklin Bridge and Lardner's Point Park below the Tacony-Palmyra Bridge - and a growing skein of trails are allowing Philadelphians to begin to return to the water.
"Lots of people are going to see the Delaware River in a very different way," Nutter said last week as he stood in the refurbished Pulaski Park, celebrating the opening of the Port Richmond Trail. "We have much more work to do, but it's a wonderful start."