In the grand vision for the seven-mile central Delaware River waterfront that Mayor Nutter has endorsed, a generous ribbon of green and hiking trails along the water will showcase urban-scale neighborhoods where people live, work, and shop - all of it pedestrian-friendly and transit-accessible.

That's the dream, anyway. Whether it becomes a reality or turns into a pipe dream remains to be seen.

In just 10 years, San Francisco managed to transform 300 acres of former brownfields along its waterfront into the vibrant Mission Bay neighborhood of condos, cafes, and biotech labs, as detailed Friday by Inquirer architecture critic Inga Saffron.

So it can be done. In Philadelphia, a promising next step comes Tuesday, when the City Planning Commission takes its first formal look at new zoning rules proposed for the area.

The final rules will help determine how the development takes shape. Halfway measures probably won't be good enough. The starting point, after all, is a traffic-clogged, poorly utilized, and partially decaying expanse.

Like every urban renewal, this one will ruffle feathers. Some developers, for instance, resist a key recommendation: extending the street grid to the river.

The grid plan could well rule out more sprawling, gated condo communities, but it's the most exciting aspect of the blueprint drafted by University of Pennsylvania consultants PennPraxis.

The same holds true for a planned greenbelt along the river and easy recreational access from Columbus Boulevard and Delaware Avenue.

Under City Council's arcane tradition of district prerogative, Councilman Frank DiCicco is drafting the zoning rules - in consultation with top Nutter aides, commerce director Andrew Altman, and planner Alan Greenberger. That leaves a lot of power in the hands of one councilman.

The first cut at the complex task resulted in a greatly weakened version of the PennPraxis design. DiCicco's own spokesman said some stakeholders questioned whether he was catering to "the developers' whim" - a claim he disputes.

In fact, the first draft said waterfront property owners had to set aside only a 50-foot buffer. The car was still king, inasmuch as free-standing garages could be built easily. Public access to the river was less plentiful.

Now a number of amendments to the proposals put out by DiCicco Thursday have improved the outlook. They're aligned more closely with the expansive PennPraxis plan - an outgrowth, DiCicco says, of talks with stakeholders.

Banned are big-box retail and stand-alone parking lots - a worthy proposal, alas, that would come too late for the proposed SugarHouse slots barn and 10-story parking garage that will dominate the north end of the river.

More fine-tuning could only help, however. Zoning rules that defer too much to the old ways of thinking about the waterfront will leave the dream unfulfilled.