The 30th Street area is marked by a few very large presences: the railroad and the two universities, Penn and Drexel. Both are putting heaping hands into the pie that is its redevelopment and (hopeful) eventual extension of Center City, particularly as these institutions are something of a bulwark separating it from the neighborhoods beyond.
But Penn does not operate north of Chestnut, and Drexel only operates parcels south of Chestnut facing it. This is resulting in an incipient micro-fault line splitting the two from one another, and handcuffing access along the 100 blocks of 31st and 32nd*.
Why is this important? Well, looking at the Drexel Master Plan, 31st St. is to become a boulevard framing the High Line, and 32nd (already is) a greenway that links the campus together. Neither are extended south of Chestnut. Both should be.
This is increasingly apparent along the further-developed 32nd: Drexel is extending active uses as far as campus borders allow, but the corner of 32nd and Walnut is dominated by a large Penn parking garage--one that turns blank faces (somehow) to each and every single street it faces, which in turn makes the Penn part of this block have a borderlands feel and 'tood--one not at all helped by either the uncovered SEPTA line along the 32nd St. right-of-way or by the way Penn has the street become Rittenhouse Labs' access alley.
But it is also increasingly apparent along 31st, which Drexel wants to turn from another glorified alleyway into a proper street**--in fact, a boulevard--as part of its redevelopment program of the Abbots Dairies, Five Star, and Bulletin sites. 31st Street lies under the High Line and is thus defined by it; once in the Penn hegemony across Chestnut, the 3100 blocks of both Chestnut and Walnut are, however, High Line Park, now redundant with Penn Park and thus a placeholder green space.
Again, therein lies the problem, and along it, a fault line. Penn is currently utilizing its Walnut Street properties relatively marginally; Drexel is only extending its much higher-use plans to Chestnut. Whither between Chestnut and Walnut? Will we see a sharp delimitation between Penn and Drexel's hegemonies?
Penn is currently content with its situation, despite the fact its master plan is all about taking Penn to the river. The most recent update did not take Drexel's improvements or intended improvements across the street at all into account; it still treats Penn as something of a monolithic juggernaut. Instead, the update includes the (albeit also-necessary) still-unbuilt Hill House and building on its parking lot on the 3300 block of Chestnut.
Still, Penn's Walnut Street property has to be considered a landbank, and the best way to integrate it as an urban grid is to integrate Drexel's improvements into its plans. Drexel's current master plan was developed under John Fry's aegis, and as the existing Penn framework was developed when he was there, I don't doubt John Fry still has many friends at Penn.
The solution--already alluded to--is simple. Extend 31st and 32nd St. improvements to Walnut. On 31st, this will involve extending the streetscape the Drexel buildings are beginning to frame across High Line Park, allowing its other section to be redeveloped; this boulevard would have a wedge shape (from ~150 ft. at Walnut to ~100 ft. at JFK) and thus thrust Penn Park into the Drexel hegemony. The tri-level bridge structure at 31st and Walnut would become the boulevard's natural terminus, as 31st would loop around, providing access to 30th St.'s lower level; the greenway would exist at the lowest (31st St.) level, offering a naturally-flowing park connection. A bike ramp to Walnut would also be built, with a traffic light at the intersection allowing for a scramble crossing.
32nd's improvements would be rather more expensive. Here, the major issue is service bay access; this can be dealt with by linking the existing service bays in the Sansom St. bed into a new lower level of 32nd St. On top of this a greenspace like the one across Chestnut can be built, a easy concrete deck with the masonry retaining wall separating SEPTA and the public street becoming a pier for the structure above. Another scramble would be built at the intersection of this and Walnut.
This is only half the solution, though. While we have ensured that both 31st and 32nd have become platforms for development through the 30th St. core, the second half is to capitalize on this offering. Again, what Drexel's doing along 32nd leads the way: Chestnut Square, the new LeBow College of Business, and improvements at both Stratton (a new retail annex) and Disque (a new learning terrace, probably a reskinning) are all evidence of intensive reurbanization.
For the Left Bank, this will likely mean shifting onsite Penn functions to the 32nd St. side as the current (High Line Park-facing) side would become shared service bays and parking entrances. And for Penn, this means (a) axing the 3201 Walnut garage, replacing its spaces in the High Line Park redevelopment, and redeveloping it into a significantly more intensive use, (b) opening Rittenhouse Labs' notoriously blank Walnut Street wall, and (c) offering an active urban use at 3200 Walnut.
More work needs to be done along 31st, where, of six potential streetwalls, only one is fully functional. For Drexel, the Alumni Engineering Labs building needs to be totally rebuilt, as it is aging, architecturally inferior to Stratton, and shows evidences of poor maintenance; a renovation of the (much newer) Center of Automation Technology to provide for a 31st St. street frontage is also recommended. Drexel also intends to build a new Engineering building on the Abbots Dairies site (to replace Hess and supplant Alumni while it's redeveloped, speculatively) and rebuild Drexel Plaza around 3001 Market, extending 31st to JFK.
This leaves under Penn's aegis the High Line Park. As already mentioned, it is now highly redundant with the much newer and larger Penn Park just across the street, and from an aesthetic perspective, its continued existence breaks streetscape too early. Not to mention the spaces in the 3201 Walnut garage are to be buried in the core of this site! The site offers an ideal space for larger, loft-style structures, perhaps as an extension of the Left Bank, but more likely sharing a service alley with it but being de novo construction like Domus or Chestnut Square down the street.
A final note: The south side of this stretch of Walnut hosts the Class of 1923 Ice Skating Rink, one of the most underutilized buildings on Penn's campus as well as the Cira South and Penn Park parking lot landbank sites. Since Penn, like Drexel, owns huge plots of land in this area, the character of their development will reflect the character of development in this area in general.
Someone get John Fry on this.
* Yes, I know there are stairwells onto both from Walnut, but they are only accessible from the less-traveled north sidewalk, and relatively rarely used. My impression of the area is that that Walnut from 30th to 33rd is a superblock, not an integrated part of the street grid--this is at least in part caused by the lack of safe crossing available at either 31st or 32nd.
** Despite the fact that the Drexel buildings themselves are one of the primary reasons 31st feels so much like an alleyway.