is executive director of Penn Praxis at the University of Pennsylvania's School of Design

Tomorrow is the three-year anniversary of Mayor John F. Street's signing of the executive order authorizing the planning of the central Delaware River waterfront.

Against the backdrop of rampant pre-Great Recession real estate speculation fueled by the specter of two casinos, the planning process forged a rocky road across Philadelphia's long-suffering planning and development landscape. Led by Penn Praxis and funded by the William Penn Foundation, the process engaged more than 6,000 Philadelphians in the creation of an action plan for the riverfront that would extend Philadelphia's intimate fabric of human-scaled streets and parks across the chasm of I-95 to the largely suburban geography of the automobile-scarred central Delaware.

Today, the vision has been embraced by the city, serving as the basis for zoning legislation - introduced by Councilman Frank DiCicco and passed in June by City Council - that establishes public-access standards along the river. These are significant accomplishments that benefit Philadelphians. Indeed, one need only look at the Action Plan for the Central Delaware, released last year, to see that many of its goals have been achieved:

The Delaware River Waterfront Corp. was created by Mayor Nutter from the ashes of the Penn's Landing Corp. in January. The new agency, led by Tom Corcoran, is open and transparent and dedicated to implementing the city's vision for the central Delaware.

The expectation that the waterfront will be a public amenity is now a given, secured by DiCicco's zoning ordinance. Three years ago, privatization was a serious concern. An interim trail between Washington Avenue and Tasker Street is a portent of a greenway along the river that will reap public-health, ecological, and economic development benefits for generations.

Parking lots are giving way to parks. Penn Treaty Park, a long-forgotten jewel in Fishtown, has an elegant new master plan, and Pulaski Park, at the base of Allegheny Avenue, will become a connecting node along the north Delaware trail. Pier 11 at the foot of Race Street will be designed by James Corner's Field Operations and establish world-class landscape design standards along the central Delaware. Pier 53 at the foot of Washington Avenue will become South Philadelphia's first riverfront park. These green shoots are a bellwether of the emerald necklace that will eventually ring the river's edge.

While we have come far in three years, there is much work still to do:

The waterfront corporation will soon hire a consultant to create a master plan to guide development. The public must remain vigilant and give the planners and the city the courage to extend streets to the river, provide generous public access, build a robust public-transit network, enforce high-quality design standards, and tackle the Gordian knot of I-95. The interstate chokes the riverfront from the city. As it is rebuilt over the next 20 years, will we dare to imagine a city with I-95 buried, capped, or brought to grade as a great urban boulevard?

As the city readies for the first comprehensive planning process since the 1960s, the riverfronts should be recognized as special assets. They are part of the neighborhood, citywide, and regional green connective tissue that is vital to our social, economic, and physical health. We have the opportunity to establish green infrastructure corridors that enable traditional economic uses, such as the working port, and serve as new kinds of public spaces. New York City recently enacted waterfront zoning for all 578 miles of its shore. Is Philadelphia ready to recognize that rivers transcend councilmanic boundaries and do the same?

Philadelphia's vision for the central Delaware is long-term and aspirational - based on civic values and principles drawn from an extensive public conversation facilitated by the Penn Project for Civic Engagement. The vision positions the central Delaware at the center of a thriving, competitive 21st-century metropolis - one with great public spaces and urban amenities that will attract and retain the knowledge workers of the next economy. Despite the pressure to build big-box, automobile-dependent development along the river, Philadelphians should stick to their principles in making the riverfront a true extension of the city's neighborhoods.

We've come far the last three years. We must continue to believe that Philadelphia deserves a world-class waterfront.