The Nutter administration loves to plan stuff. It has probably turned out more master plans in the last four years than the previous two administrations combined. And yet there's one part of the city that it has steadfastly refused to discuss: the I-95 corridor.

Vastly overbuilt in the mid-'60s, the 10-lane superhighway cut off the city's - no, make that America's - most historic neighborhoods from the Delaware waterfront. The broad canyon is a key reason that Penn's Landing, and hundreds of acres along the river, remain undeveloped today.

Given the growing interest in capturing the waterfront's economic potential, the future of I-95 should be a hot topic in City Hall. Instead, it's virtually taboo. The highway barrier rated only a modest mention in the two most important planning reports produced by the Nutter administration - the Delaware waterfront master plan and the citywide comprehensive plan for 2035. The lack of interest is baffling because the segment of the aging interstate that runs through Center City is due for a federal overhaul in the next 25 to 30 years. In the world of highway engineering, that's practically tomorrow.

But if City Hall won't talk about this important issue, there are others who will. On Thursday, the Philadelphia-based group Next American City is holding a panel discussion at the Academy of Natural Sciences on the hot topic of highway removal, with a focus on I-95's Center City segment, between Race and South streets.

Next American City is a hybrid enterprise - part think tank, part website, part magazine - that does deep dives into the issues facing cities. It's Philadelphia's good fortune that its founding editor, Diana Lind, chooses to make the city her home base.

As an outsider looking in, she was struck by the silence surrounding I-95, given how many other U.S. cities were committed to ripping out their downtown freeways. "I don't understand why we're so reluctant to look into something that could produce a big win," she told me recently.

To get a conversation going, Lind will bring in some of the country's top removal advocates, including former Milwaukee planning director Peter J. Park, who led the successful campaign to raze Park East Freeway; Providence, R.I., city director Thomas Deller, who yanked out a piece of I-95 in his downtown; and Aaron Naparstek, founder of the influential

I've come to know Park and Naparstek pretty well over the last few months. Like me, they are Loeb Fellows this year at Harvard's Graduate School of Design. We've had dozens of conversations about highway removal - frankly, it sometimes feels like it's all we talk about. So, this is a warning as well as a disclosure: They can be very persuasive.

The question is whether the Nutter administration will be listening. The person who should lead the charge on I-95 is Rina Cutler, deputy mayor for transportation. But Cutler is a staunch opponent of modifying the existing highway design and is the main reason the topic is off-limits in City Hall.

That bothers Lind because there isn't much time left for discussion. Because I-95's Center City segment is listed for an overhaul around 2040, she calculates that engineering work will have to start sometime around 2020. That leaves just eight years for the city to come up with an alternative plan and win public consensus. If the city does nothing, the federal government will take the inaction as an OK to replicate I-95 as is.

To Lind, this is borderline crazy. "Why in the world would we build the infrastructure of 1950 for 2050?" she asked.

I asked Cutler the same question recently. Her response was that Philadelphia can't afford to alter the status quo. Many here have proposed burying I-95 in a tunnel, as Boston did with its Big Dig. But that $14.8 billion project ran so far over budget, and required so much additional money from the state, that it nearly bankrupted Massachusetts' highway authority.

"With the focus in Washington on spending less and less, we'd be hard-pressed to get anyone to consider funding to bury the highway," she said.

Still, that doesn't mean there aren't other, less-costly solutions.

The cheapest would be to upgrade the two caps that cover I-95's Center City section, which runs partially depressed in a trench below the level of Front Street, south of Market Street. The caps are home to two small parks, but you'd hardly know it. So claustrophobic is the landscaping that people are wary of entering. Hedges cut off the visual connection to the waterfront, making the Delaware feel a million miles away.

The city could easily redesign the caps. The recent waterfront master plan goes a step further and suggests extending the caps down to Penn's Landing. While a sloped park would definitely improve the connection to the waterfront, the city has yet to go after funding. One of the drawbacks is that it would not create any new land for development to offset the public investment.

That's why many are pushing for real surgery. They say Philadelphia should give up on improving the flawed caps and demolish the highway's Center City segment, south of the Ben Franklin Bridge. Traffic drops off dramatically at that point. The segment also happens to be redundant, since the six-lane Columbus Boulevard runs parallel to the interstate. Motorists could be diverted to the boulevard, then they would pick up I-95 again near the Walt Whitman Bridge.

Removing that stretch of highway would enable the city to extend the street grid to the river. With real streets and blocks, the waterfront would have the potential to become a real neighborhood.

Of course, removing I-95 might create additional congestion on Columbus Boulevard. But the question is whether fears of increased traffic should be the guiding consideration. Adding five or 10 minutes to a trip to the airport seems like a small price to pay for reuniting Philadelphia with its historic waterfront and opening the river to new, tax-generating development.

To get a sense of what the waterfront could be, take a look at the urbane proposal for reimagining I-95 by Clara Romera and Rene Biberstein, the two University of Toronto students who won this year's Ed Bacon Student Design Competition. They suggested that Philadelphia remove the highway's Center City segment and build a version of Rome's Spanish Steps down to the waterfront.

There are no doubt other good solutions. Two design instructors at the University of Pennsylvania, Harris Steinberg and Fernando Micale, hope to identify some this spring. They're teaching a class on highway removal that will look at six cities that are in the process of eliminating their downtown freeways.

What should be clear by now is that Philadelphia has choices. History doesn't have to repeat itself so long as City Hall is willing to talk about its future.

Contact architecture critic Inga Saffron
at 215-854-2213,, or @ingasaffron on Twitter.