THINGS are starting to move along the Central Delaware - literally.

Just this week, the Delaware River Port Authority (DRPA) is holding hearings on transit alternatives for a light-rail line along the river. This puts the exciting possibility of creating a dense, urban, pedestrian-friendly extension of the city to the waterfront one step closer to reality. And it's in line with the recommendations of the city's 2007 Civic Vision for the Central Delaware, which calls for connecting future development along the riverfront with the public transit system in a comprehensive and forward-looking fashion.

At the same time, the city's newly reconstituted waterfront agency, the Delaware River Waterfront Corp., is about to embark on an ambitious master-plan process for the seven miles of the Central Delaware riverfront from Oregon Avenue to Allegheny Avenue.

The master plan will build on the core civic values and principles that formed the foundation of the Civic Vision for the Central Delaware. The plan will turn the vision into an official working template for future public investment in infrastructure such as streets, parks, transit and the future of I-95.

These two efforts affirm the tremendous untapped potential of the Delaware riverfront and signal that city and regional leaders are serious about promoting growth along the river that is sustainable and transit-oriented.

There's only one problem: The two efforts should be aligned so that the work of the master plan - a process that will establish land use and density for development along the Central Delaware - guides decision-making on the transit extension. Ideally, transit supports land use.

A new waterfront light-rail line will

be a wonderful addition to the city's public transit, but how it's integrated into the larger transportation network is critical.

The master-planning process will allow the city to carefully consider the relationship to the Market-Frankford El, connections to Penn's Landing and how to mend the yawning chasm of I-95.

We know that the entire stretch of I-95 from South Philadelphia to Port Richmond will be rebuilt in the next 20 years - and now is the time to plan for an integrated infrastructure program that doesn't treat highways, streets and transit as stand-alone systems.

We should be thinking about long-term integrated investments in roads, mass transportation, open space, green infrastructure and public amenities that will heal this part of the city and not create additional urban infrastructure baggage that will create damage that will take generations to undo.

The Central Delaware is poised to begin the next important step in its evolution from a largely disconnected, post-industrial workplace to a vibrantly energized contiguous part of the city.

Investing in the right physical infrastructure now will make all the difference in years to come. Let's let the Delaware Riverfront Waterfront planning team guide the future alignment of Delaware Boulevard, create the network of streets and parks that will add value to private development and shape the future of I-95 so that it is no longer an impenetrable obstacle to development, public waterfront access and the future health of the city and region.

The moment is right for this kind of comprehensive planning.

The Obama administration has changed the game in Washington in terms of cities and infrastructure. They are placing a high value on metropolitan regions that understand the benefits of coordinated, long-term, sustainable investments in infrastructure that leverage existing urban and economic assets.

We have the opportunity to position Philadelphia and the region for considerable federal investment that will lessen our dependency on fossil fuels while building on our dense urban heritage and significant ecological resources.

A new rail line along the Central Delaware should be part of this larger worldview. It should be connected to a seamless, world-class transportation network, including water transit, that allows the Philadelphia-area transit rider to change transportation modes effortlessly as he crosses the city, and region.

LET'S DREAM BIG, Philadelphia.

This is the moment to seize the brass ring and make a run for large-scale, comprehensive, transformative infrastructure investments that will pay us back in spades in the decades to come. Opportunities for investment of this kind come along only once in a generation - if we're lucky.

The future of the city and the region are riding on the choices we're making now.

Harris Steinberg is the director of Penn Praxis at the University of Pennsylvania.