The Delaware River Waterfront Corp. has completed its first round of designs for the $21 million central portion of a 3.3-mile walking and cycling trail planned between Fishtown and South Philadelphia.

The city-affiliated nonprofit, which oversees development along central Philadelphia's Delaware River waterfront, plans a public forum on Monday to present sketches of the proposed trail segment running along Columbus Boulevard between Spring Garden Street and Washington Avenue.

The event is to be held at 101 S. Columbus Blvd., site of the Blue Cross RiverRink Summerfest attraction.

The section is planned as part of a $225 million waterfront development initiative that also includes capping a portion of I-95 with a four-acre park. Features of the trail segment are to include a two-way bike path and separate pedestrian sidewalk, as well as new landscaping and streetlamps and furniture, DRWC said in a release.

The agency said it will refine its design based on feedback from community members and regulatory agencies, before getting its permitting and going out to bid. Construction is projected to last up to two years.

Plans call for the central trail portion to link with a northern segment, now being built, that cuts east from Columbus Boulevard to run along the waterfront from Penn Treaty Park, at East Columbia Avenue in Fishtown, south to the SugarHouse Casino.

At Washington Avenue, the central segment would link to another waterfront trail section ending at the Pier 68 recreational site, beside a parking lot for the Walmart-anchored Pier 70 shopping center.

Work is also underway on the southernmost section of that trail segment, between the Pier 68 site and Tasker Avenue.

The only section of the planned trail that the DRWC does not yet control runs along the waterfront between Reed and Tasker Street, along the eastern edge of a 18-site where a Foxwoods casino once had been planned.

National Realty Investment Advisors, a Secaucus, N.J.-based development company that specializes in Philadelphia projects, now plans a complex of 169 four-story homes on part of the land.