As cyclists whizzed by on the Schuylkill path, Mayor Nutter and a host of bike advocates announced a new coalition aimed at completing 750 miles of trails over the next 20 years in the Philadelphia region.

About 250 miles of the bike and pedestrian roadways have been completed, and 50 more are "in progress," said Alex Doty, executive director of the Bicycle Coalition of Philadelphia, a member of the new coalition. Finishing the remaining 450 miles of trails and connecting them to current routes is expected to cost $250 million, or about $12.5 million annually for 20 years, Doty said.

That may sound like a lot of money, but Doty said it equals about 1 percent of yearly highway and transit capital spending.

Coalition members, including Bartram's Garden, the Clean Air Council, the Delaware Valley Regional Planning Commission, the Schuylkill River Park Alliance, and the William Penn Foundation have dubbed the proposed trail network "the Circuit." That name was suggested by Fairmount resident and cyclist David D'Alba.

Organizers said that expanding and connecting the paths would make Philadelphia more appealing to employers and people who want easy access to the outdoors to exercise or commute to work.

"There is a growing recognition that without being connected, this has less value," Doty said of the current bike paths.

In connection with the announcement, the Circuit Coalition unveiled a website, www.connectthecircuit.org, where bicyclists and walkers can plan trips using current trails and streets.

The Circuit would connect Bucks, Montgomery, Delaware, Chester and Philadelphia Counties in Pennsylvania and Mercer, Burlington, Camden and Gloucester Counties in New Jersey. Currently, the longest stretch of trails within the circuit measures 44 miles.

"These trails are an important part of what makes Philadelphia a great place to live, work, and raise our families," Nutter said.

Over the last two years, $28.2 million in federal funds and a $10 million grant from the William Penn Foundation have helped develop trails in the nine-county area.