Circuitous and Serpentine

With the recent announcement that they are acquiring 901 Market from Vornado (a New York landlord's only significant Philadelphia holding) for $60m, PREIT has finally completed the onerous task of assembling the Gallery complex into a single ownership structure. To do this, they have had to acquire the former Strawbridge's and to make peace with the City and the RDA. And this had to be done before any significant modernization effort could get underway.

All this time, the Gallery has been declining; I documented its effects last fall. After withstanding the 1980s urban retail exodus, the first chink in its armor was cut in 1989, when Stern's (having replaced Gimbels) pulled out and the space was restructured for Clover and more office space. This became a new equilibrium through the 1990s (similarly-placed Kmart replaced Clover in the space) until 2006, when Macy's closed the flagship Strawbridge's, moving their operations to the Wanamaker Building, in a space that remains significantly undersized relative to shoppers' needs. Note to Macy's: Don't try to cram yourself into a Lord & Taylor space, it just doesn't work.

After 2006, the Gallery's fortunes accelerated on their downward track. Without Strawbridge's to anchor it, the east wing failed; the west wing has remained significantly stronger, but still weak. The profit margin-poor food courts have become the leading customer draw, further isolating activity on the concourse. Nearly all the Strawbridge's space has been turned into offices--State and City offices. And hotel guests at the Loews, Marriot, and Hilton Garden right next door are bussed to King of Prussia as the Gallery further weakens.

Two more announcements: (1) PREIT is planning on pumping $300m into the Gallery, totally repositioning it, and (2) Kmart is not renewing its lease.

This is good news! The Kmart space has long split the Gallery into two separate wings, and half the office space sits unused. Meanwhile, the Gallery is the key to Market East, and strengthening it will also strengthen the corridor.

What PREIT exactly has up its sleeve is still a mystery, but I would like to present my optimal Gallery redesign, based on a modification of the Westfield San Francisco Centre layout optimized for the much more linear Gallery corridor. Westfield, where they undertook a $440m renovation in 2006 completely replacing the interior of the former Emporium department store, also functions as a model for PREIT going forward.

Pink is offices, sky blue inline retail, blue anchors; orange the multiplex, yellow the food court. Brown is Market East's platform level.

In this model, I have retained three anchor spaces. The basement and first floor of Strawbridge's is one anchor space; the 2nd, 3rd, and half the 4th floors of the Gimbels the second, and the extant Burlington Coat Factory the third. In a nod to Chicago's former Carson, Pirie, Scott, I have placed City Target in the remnants of the Strawbridge's space; a Century21 is placed in the Gimbels space, becoming the complex's dominant anchor. A multiplex uses east wing third floor space, while the main food court is relocated to Strawbridge's atrium, the kitchen spaces along the party wall between the Gallery and the original Strawbridge's on the second floor. Cross-floor access is revamped, with the multiplex's main entrance being along the corridor leading to Gallery I's parking garage, and a secondary entrance being from the food court's new "Dining Porch"; the third floor on the bridge across 9th will be eliminated.

The large spaces left behind on the first floor will be subdivided as need be, with an optimal mix mixing medium-size "big boxes" (e.g. Toys "Я" Us, Barnes & Noble, Bed Bath & Beyond, etc.) and inline stores. The goal of this project is to attract budget fashion retail (Forever 21, H&M, Hollister, Aeropostale...) to the upper inline levels, while having casual eateries and at least one secondary anchor face the street. Redevelopment here will complement Girard Square, although the large anchor space in the latter complex does not currently have a tenant.

Finally, a major element of any Gallery project is to activate the three built-in pads. As Hilton now has two nameplates in proximity (Home2, Hilton Garden), I recommend a Hilton proper on the 1001 Market pad site, and rental apartments on the 1000 Filbert; currently, however, there is no good use for the east wing pad site.

Remember above all that the success of the Gallery, both internally and as cityscape, is crucial to the success of Market East as a whole. To make Market East a place people want to go to, the Gallery must be a place people want to go to; to see development on the un- and underbuilt parcels on Market East, Market East must be a place people want to go to.

The Space Between

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.

Easy, Medium, Hard

Flourtown. Jenkintown. Ardmore. What do all these places have in common?

They're all four-lane Main Streets in rights-of-way really too narrow to handle them. Too much of the right-of-way is dedicated to making through traffic move fast; too little to ensuring good pedestrian movement. Each of these Main Streets is a historic Main Street with average or above-average place intensity; in each, there is no good reason to sacrifice parking and sidewalk for traffic lanes.

Let's start with Flourtown. Built as a linear village sprawling along Bethlehem Pike, it stretches (and has stretched for at least 150 years) through Springfield Township--its primarily population concentration--from Chestnut Hill to Whitemarsh. It is subdivided into three sections: Erdenheim and Valley Green bookend Flourtown proper.

Now, tell me why on earth is this stretch of Bethlehem Pike four lanes? Certainly, it used to be the south end of the main trade route from Philadelphia to the Lehigh Valley--which is why Flourtown grew in the first place--but that function has since been bypassed by the Fort Washington Expressway, which connects rather into Cheltenham and Ogontz some miles off. A suburban extension of Chestnut Hill, Bethlehem Pike in Flourtown functions as a natural Main Street, albeit one cut in several places by strip malls, and never gets the kind of traffic four lanes should demand. Indeed, in a spontaneous experiment, Aqua has been repairing water pipes under the street, which has halved effective capacity, without inducing onerous traffic conditions.

Its through-road capabilities diminished, it is apparent this stretch of Bethlehem Pike needs instead to capitalize on placemaking to help further develop Flourtown. This can be done by simply getting rid of the two extraneous lanes, narrowing them to parking lanes, and in the four-feet-a-side of added space run either (a) a bike lane, or (better) (b) expand the sidewalk.

If Flourtown was easy, Jenkintown is harder. PA-611 runs along its Main Street, Old York Road, which (due to the region's underbuilt highway system) is the main artery from Philadelphia to points north. Old York Road links Broad Street with Easton Road, the long-distance pike, and is as such still very much a key trade route.

But it is not an insurmountable problem. Like Ambler, Jenkintown is enough a place to hold its own without through traffic--traffic that usually stops not on Main Street, but rather in strip malls beyond (in this case, primarily Willow Grove to Noble). And Easton Road is reasonably straight and meets the city at Cheltenham-Ogontz, allowing 611 traffic use of (very) wide Cheltenham Ave. to Broad St.

...Unfortunately, this passes through downtown Glenside and Roslyn. If the point is to bypass downtown, what use is it to simply bypass one downtown for another? A better route between the two would be Rices Mill Road-Highland Avenue, which would thread between Wyncote and Glenside.

The hardest is dealing with Lancaster Pike, Ardmore's Main Street, in a situation like 611, but with more downtowns still--this would also involve a bypass of Bryn Mawr.

The reason this is more difficult is because of the nature of the Main Line, and because no useful bypass exists for Wayne or Paoli further up. Regardless, a feasible bypass begins at Villanova, and follows Spring Mill Rd. to Montgomery Ave. This route follows Old Lancaster Pike to 54th St., a better one would follow Wynnewood Ave./Rd. back to Lancaster Pike by Lankenau, sucessfully bypassing the heart of the Main Line but leaving the through route intact.

All of these solutions are inexpensive. I am not talking about building new freeways here; rather, I am simply talking about re-signing numbered highways along different routes to allow strong Main Streets better placemaking. Keep in mind that Ardmore, in particular, is a major transit village and a development model for much of the Philadelphia metro.

Feedback Loops

Earlier today I was reading the Atlantic Cities article on whether or not Millennials will stay in the cities they now call home, and through the comments, when I noticed:

What will happen when the baby boomers who are living in suburban mansions they've built over their lifetimes find that their home, which is their biggest if not only financial asset, doesn't have any appeal or demand to younger buyers who prefer city life? If they can't cash in on the value of their home because demand is down it means they can't access what they thought would have been their retirements savings... 

An unasked question? Perhaps, but in the answer we find the driver of a feedback loop: If (a) you can't access your retirement savings, (b) you can't retire, meaning (c) you have to stay in the workforce. Since the workforce isn't growing (in fact, it's shrinking) that means (e) you're taking a job away from a Millennial, which (f) deprives them of the opportunity to buy your home, thereby (g) preventing you from accessing your retirement savings (forcing you to keep working and so on)...

Feedback loops are compounding cyclical phenomena, and what I have just described is a compounding cyclical phenomenon--a feedback loop. Note that this feedback loop assumes the New Geography* status quo, that of continuing unhindered suburbanization (despite the considerable evidences to the contrary).

In the New Geography worldview, living choice is a function of affluence, and suburbanization a function of increasing wealth. But the ideal of increasing wealth assumes unlimited growth--a common tenet of economics, but one that is decreasingly justifiable. Even assuming economic stability (note: not stagnation, although there is no doubt we live in an economically stagnated era), we note that by the rather poor choice of storing your "savings" in your home** you have inadvertently triggered a feedback cycle whose ultimate effects are (a) a devaluing of your home and (b) a mismatch between your home's market and buyers' markets--because, in search of jobs, those who would ordinarily replace you have moved on: in this case, to the cities, because that's where the strongest economic engines are.

Multiply this thousands upon thousands of times and you go from a few people making bad choices to a macroeconomic trigger.

How stunningly naïve New Geography's worldview is! Their entire analytical framework is built on a single aberration in American history, a hopelessly linearized misunderstanding of the rise of American (autocentric) suburbia. To look deeper, which we must, we have to recall that from 1950 to 1990, American cities were locked in a negative feedback loop, one triggered long before their population peaks.

We must understand the Chicago School is a reasonably accurate understanding of prewar urban dynamics, and in all Chicago School models, immigration was the population dynamo. Can you imagine the effect of the Immigration Act of 1924, crowning glory of the nativists? Suddenly, cities stopped having a ready replacement supply for those leaving, as the immigration quota was (and continues to be) far too low for replacement. Worse, the quota failed to solve the problems it claimed to, and produced new ones--illegal immigration and visa fraud wouldn't exist if we didn't have a quota-based immigration system.

Of course, like all feedback loops, the effects wouldn't become apparent for decades. The Great Migration was initially able to hide the dynamo collapse, but it is no coincidence city populations plateaued 1920-1950; worse still, the Great Migration happened at the same time as the nadir of American race relations. Like all poorly-thought-out "solutions", this, unsurprisingly, increased the problems of the city.

The second major trigger of suburbanization was the automobile. Here was this absolutely amazing invention that could whisk you from skyscraper canyons to the Grand Canyon. And, once the opposition movement was quelled (thanks in no small part to astroturfing on a grand scale) it suddenly became--not only ubiquitous, but essential. Every new development after ca. 1930 had garage space--in the beginning, rear-loaded. But cars are the enemy of cities. Everywhere, they push things apart to their own scale, and their scale is gigantic, inhuman. At first, developers applied the living traditions to humanize their streets, their blocks--but to no avail. A pushing-apart is evident beginning in 1930s developments, culminating in exurbia. (There's a reason postwar suburbs are called autocentric.)

What happened is simple. After their fathers were defeated in the great car wars of the first third of this century, the Greatest Generation youth came to adulthood in a society re-forming around the car. And this wondrous new(ish) invention could do great things--but at a price. Worse, those people were all over the place in the places they grew up. What was a fellow of the Greatest Generation to do?

The Baby Boomers were not the first suburban generation--merely the first to grow up there. The Greatest Generation chose suburbia. They were the first "suburban" generation. And in that choice, they set in motion a feedback loop that would eviscerate cities.

In their wake, it wasn't just the middle class shriveling. The collapse of the immigration dynamo three decades previous reared its ugly head: there was no new middle class forming. Tax bases began to hollow out, while at the same time, as a greater percentage of residents remained in poverty, the need for services multiplied. The collapse of cities wasn't just a result of the formation of suburbia--it was as much a result of turning off the immigration spigot. It was the result of rampant social mores that wouldn't begin to change for two more decades. It was the result of an entire finance built around these mores...

And once those gears had begun to move, no matter how many well-intentioned people tried to stop them, they would not stop. The collapse of American cities that has been the defining urban reality for Boomers' lifetimes would further compound on itself by driving Boomers away, ever further away, and would drive their attitudes about the city, the way they viewed the thing.

The nadir of the American city occurred around 1990, and several factors led to the feedback loop stalling--most importantly, bringing the crime rate under control. The maturity of Gen Xers, who did not have the memories the Boomers did, also helped: it was under their purview that urban middle-class populations, particularly around downtowns, finally stabilized and, over time, began growing again. And this was both catalyzed by and further catalyzed the growing idea of downtown as destination: a place for nightlife, fine dining, and culturally important activities***. This middle-class stability, in turn, fuels the only long-term sustainable solution for dealing with what has today become the most pressing urban issue: schools.

It will be on the strength of how well Millennials deal with schools, how much they have the initiative to deal with them, and how much factors-at-large force them to deal with them, that the American city will be said to have stabilized--or will grow again, and explosively.

Schools are at the crux of the Millennial urban feedback loop.
______________
* No, I will not link to that wretched hive stricto sensu.
** Or, more accurately, your land; the improvements are a constantly depreciating asset--like your car--while the proximity value of the land it's on increases slightly year-over-year; part of the inflation of the housing bubble was an overvaluing of suburban land (combined with a persistent undervaluing of city land).
*** It is also important to note that attempting to isolate elements within a feedback loop has the effect of short-circuiting the whole thing. Arts and entertainment districts fail because of this; "natural" arts and entertainment areas blossom and then are subsumed within the greater system. When they arise, they can be marketed, but they cannot be created out of whole cloth.

Dealing with Zoo

In the comments on the last post, the conversation--inevitably--turned back to Zoo, and I pointed out in the comments that

...Zoo does have a very real time cost, and the only way to ameliorate it is to, well, bypass it. And the only way to bypass Zoo is to build a new Schuylkill crossing.

So, now that we have established how to provide high-speed Airport service and augment the 30th Street approaches; so, now that we have established that the existing alignment is operationally superior and that neither speed nor capacity is an issue south of 30th Street, we must take a look at what is the real crux of Philadelphia's rail transportation problems: Zoo.

Before we begin this discussion, keep in mind that (a) Zoo has unused capacity and (b) of all the speed restrictions to address between New York and Philadelphia, Zoo has, or should have, the lowest priority. What this means is that we can compromise on Zoo and still get good or very good service before needing to actually address it as a problem. There is no way to solve Zoo as a speed problem without concrete, and organization and electronics need to be optimized before concrete goes in. What this means is that rebuilding Zoo is a project with a long-term outlook: 2045 or later. It is also the final element of my program of improvements for HSR in Philadelphia (see here).

The least expensive feasible HSR bypass of Zoo is this one: all bypasses will necessarily involve a new Schuylkill crossing, as the existing interlocking is optimized to provide the fastest north-south path from 30th St. onto the bridge. And due to all paths across the river needing to pass through the park, we can assume that all new sections of the alignment will be wholly underground (else we risk regulatory wrath).

The other--straighter--option would be a tunnel under Lemon Hill and Boathouse Row. Such a tunnel would, however, cancel out many of the savings achieved by abandoning Market East for a time gain of mere seconds, and would necessarily involve disturbing Boathouse Row, which lies on top of where the bored tunnel would meet the immersed-tube one. So we will not pursue this option, and instead pursue the option with the least amount of tunneling. Hence the one I provided.

This tunnel has (hopefully) a geometry offering 150 mph service, significantly faster than the 60 mph service we can optimize Zoo proper for; however, if the curvature requires a 120 mph speed limit, that would be acceptable, as the time difference would be infinitesimal. It also maximizes utilization of existing easements, beginning its approach alongside, and then under, the Schuylkill Expressway, and then curving back under the NEC ROW via an immersed tube crossing the Schuylkill under Girard Ave. It would then have to clear under Fairmount Jct.'s approach before returning to the NEC main in the Strawberry Mansion area. Designed for Velaro-, Zefiro-, AGV-, and N700-type equipment (i.e. HSR EMU trainsets) to the exclusion of all else*, this tunnel would allow for significantly steeper max gradients than elsewhere on the NEC as it is strictly a speed bypass of a complex interlocking.

Its expense--though a fraction of the total Market East tunnel's--combined with the relatively marginal improvements it offers is what cements its low priority; as I have mentioned before, upgrading the intercity network to 25kV 60Hz (with the possible exception of bypassable individual terminal systems, if clearance is an issue in urban cores) will single-handedly generate the most time savings, and be the primary mover chopping PHL-NYP time to an hour. The most expensive PHL-NYP improvement needed is, of course, Gateway, which would double the available Hudson tubes and address the choke points on the New York approach. All other projects on the line, such as what Alon Levy suggested, see time improvements of only a few seconds, which, while important, do not get the bang for the buck that addressing the archaic overhead system and the Hudson capacity issue do.

That said, this is my cost breakdown of my program of improvements, in terms of priority:
1. Zoo Interlocking Improvements
has the highest priority, as it costs the least and offers the most significant immediate speed improvement. Let's peg it at $100 million, tied up mainly in incremental track upgrades and path-sorting improvements.

It's followed by the 
2. Chester Branch HSR Line, including
2a. Hospital Interlocking,
2b. Grays Ferry Interlocking,
2c. Double-Decked Chester Branch Grays Ferry-Bartram's Gardens,
2d. PHL AirTrain**,
2e. Darby Creek Viaduct (Essington Aerial), and
2f. Eddy Interlocking, along with
2g. Local Stations (a) Bartram's Gardens, (b) 63rd St., (c) 70th St., (d) Eastwick, (e) Airport, (f) Tinicum, (g) Essington, and (h) Industrial Hwy., combined with freight improvements
3. 52nd St. Branch Reactivation, including
3a. Brill Interlocking, and
3b. Baldwin Interlocking,
that is, the integrated and interrelated complex associated with bringing HSR to the Airport via the Chester Branch. This would be the most expensive element of the whole package, as the relatively simple and low-cost interlockings are dependent on the higher-cost line optimizations and reactivations. Of particular note is the Darby Creek Viaduct, extending all the way from proposed Eddy interlocking to Tinicum, essentially a second deck over the freight Chester Branch. The cost of this complex would be in the neighborhood of $2 billion, most of which--that is, all of it railroad south of the Airport--would have to be borne by the Market East Tunnel as well (see why I say Amtrak is dangerously lowballing Market East's costs?).

Finally, the lowest-priority element of my program is
4. New Zoo Bypass,
which, as has been detailed earlier in this post, offers a minute or two time savings, but at a cost of around $1b. The Northeast Corridor is neither congested nor time-optimized enough for this cost to make sense at this time, which is why I stress incrementally improving the rest of the corridor in order to make it viable, if it must be done.

Let me repeat myself. The Northeast Corridor is currently neither congested nor time-optimized enough for a Zoo bypass to be economically feasible.
_________________
* Push-pull equipment and motor-based HSR trainsets (like the Acela, KTX-II, and Duck), none of which can achieve the maximum speed EMU-based ones can, would still be routed via the existing Zoo interlocking.
** An automated train along the Airport Line's current fishhook. The Airport Line would be extended to Chester/Wilmington via Tinicum and Essington stations.

30th St. Footnote: Hospital Interlocking

In the main post on this matter, I mentioned that the actual pinch point on 30th St.'s southern approach occurs where it passes under the High Line, as what were clearly the SB approach tracks (let's call them 3 and 4) pinch down from two to one to accommodate a large bridge pier where Track 4 should nominally go. I mentioned that I did not believe this pinch point was an issue, since it was clearly in place during the 1930s and '40s, when more passenger rail was operated than any other time in our history, and does not appear to have ever negatively impacted 30th Street Station operations. So creative dispatching can deal with a three-track approach.

The footnote is that if the inclination to apply concrete to simplify dispatching is pursued, then there is a simple way to ensure a four-track approach at all times into the station: duck Track 4 under Track 3. As (what was) the interlocking between the SEPTA and Amtrak 30th St. approaches is immediately west, or railroad south, of the High Line pinch point (see here), Track 3 can sort at the east end, and Track 4 at the west end, of this area^.

University Ave. is where it gets complicated. As it turns out, there are only four available passenger tracks across it, and split onto two different girder structures to boot. It's fairly apparent the PRR originally had at least an at-grade interlocking to sort here (a tower is still in place), but Amtrak and SEPTA, through agency fiefdom, have completely disassembled it, each crossing University Ave. on its own girder.

Fixing this so that Tracks 1-2-3-4 are N-N-S-S at University Ave.--important for implementing the proposed Chester Branch interlocking, not far to the west--will require agency cooperation as well as figuring out how the SEPTA NB track can fly over Amtrak's and still wind up at ground level to service University City station. This will be easier if we can replace the girder so that it has five tracks of space to work with, but let us try to deal with current site congestion to create "Hospital" interlocking.

This map shows how Hospital works assuming a Track 4 duckunder: Track 3 NB of Hospital becomes Track 4 SB of it, and the station throat interlocking would need to take it into account. Accepting the pinch point makes it far easier, as Track 4 can simply diverge railroad south of the Track 5 flyover (West Chester Branch EB). In either case, however, the need to end the incline at University City's railroad-west end will likely require the 30th St. approach tracks to depress slightly to make clearance; this depression will translate into a lengthening of the Track 3/4 incline between South and Walnut, with its technical limit station throat limits^.

Hospital Interlocking is the east half of a pair of interlockings intended to sort between the NEC, Chester Branch, and West Chester Branch railroad south, and 30th St.'s two approaches railroad north. The freight High Line/Chester Branch interlocking does not interact with these two in any way, and so will not be considered aside from noting that Chester Branch tracks 1 and 2 are 20 feet directly beneath two* CSX tracks.

Edited to add: One of my concerns about the Track 5 flyover was the lack of distance between the end of the University City station and the NEC main (Tracks 2 and 3). A quick check revealed, however, that there is 500 feet distance between those two points, which allows a flyover to just make an 18-foot girder clearance, 20 ft track clearance, at a 4% grade.
____________________
^ Addendum 9/20: Another possibility that occurred to me after I completed this post is to simply run Track 4 on the surface and Track 3 underneath it. That does away with the excessively complicated wayfinding necessary in what I had first described.
* The High Line has the capacity to be a two-track main; the second track is disused. This exercise assumes that freight traffic growth allows NS and CSX to rebuild the second track and CSX to run a two-track line from its main to it.

30th St. Approach Capacity?

Professional transportation engineer Liam left me this comment on my previous post, The Alternative to the Market East Tunnel:

What would be your response to criticisms that you're overlooking capacity issues at 30th Street? There are only two tracks headed south from the station, after all; the line doesn't open up to 4 until the Regional Rail tracks come in from University City.

I think it's a manageable constraint, but there's definitely more going on here than just Zoo.

This is true. Agency turf wars are a continuing problem, and have resulted, more than once, in extraneous concrete dedicated to eliminating versatility and redundancy previously built into the system--Zoo is a good example of this, where no fewer than half of the paths through the interlocking have been removed. And when the Market East tunnel was first proposed, a popular theory was that Amtrak didn't want to to have to share space with SEPTA anymore (never mind the fact they have different concourses, and different platforms with different approaches)...To put it another way, the Market East tunnel, like lobotomizing Zoo, is a concrete solution to an organizational problem.


Now we move to the real meat of Liam's specific question. There are two questions embedded within this query: (1) how do we increase the capacity of 30th St.'s south approach, and (2) (what he assumes the answer to is yes) does the 30th St. approach present a capacity problem?


The answer to (1) is that only 2/3rds of the approach's capacity, at its narrowest point, is currently in use. The ROW pinch occurs under the High Line overpass right before the Amtrak and SEPTA approaches meet; under this overpass there is room for three tracks, two of which are currently in use. Those two were originally the northbound approach; the southbound approaches have been converted into two spur tracks. Originally, they merged just before the High Line underpass and would have merged again where the upper- and lower-level approaches met, resulting in four passenger-dedicated tracks at the University Ave. overpass, tracks which would then sort into NEC tracks 1-4 and the two West Chester Branch ones.


So we can assume that--if full capacity can be reactivated--30th St.'s south lower-level approach is (technically) three tracks at its greatest pinch, and with smart dispatching (effectively) four tracks. Plenty of capacity, especially since through trains really only need four or six tracks (three platforms), half the station's current capacity (five platforms, ten tracks).


Of greater concern is the north approach, which runs straight into one of the most complex pieces of rail infrastructure in the United States: Zoo Interlocking. Remember in this discussion that the historical owner of this infrastructure, the Pennsylvania Railroad, maintained two different paths for any possible movement through the interlocking, and that there are six feeds into it (Main Line, Northeast Corridor, Reading interchange, High Line, Upper Station Approach, Lower Station Approach). For our purposes, that means the PRR maintained a four-track north lower approach, only half of which is now in use*--this is what I mean when I say Zoo has been lobotomized.

The simple solution of reconnecting several switches, and putting the Schuylkill River bridge's fifth track back in, grows the capacity of this, the busier side of the station.

Now we can address the second question. Passenger rail growth will demand capacity improvements, indubitably, but 30th Street Station was one of the last prewar passenger rail termini built in the United States, and as such, was engineered with a far greater capacity than e.g. the original layouts of any of the stations Broad Street Station was built to replace. Its approaches were state-of-the-art and able to handle 1940s-scale rail traffic without a hitch; it's very unlikely that the approach tracks within the existing PRR footprint (not all of which, remember, are currently in use) will hit "concrete" capacity limits even in the most optimistic future traffic projections (such as those Corey Best produces).


That said, as with any finite structure, there certainly is a capacity ceiling--but the traffic scale one would expect near it, which we are currently far from--would be able to justify even the most futuristic infrastructure improvements--much as the Chuo Shinkansen has become viable largely because traffic demand between Osaka and Tokyo has surpassed every capacity ceiling the Tokaido Shinkansen has to offer. Then, and only then, would a Market East tunnel become feasible.

____________
* The current situation offers two possible southbound approach tracks, but only one northbound one, through the interlocking. Only one of the southbound approaches, however, shows high-grade maintenance.

The Alternative to the Market East Tunnel

I have already spoken about my criticism of Amtrak's proposed Market East tunnel, a cogent enough piece Alon Levy relies on it and The Economist has quoted from it--but I have yet cogently articulated what the alternative is.

Part of it is, it's simple. Really simple. But it's complex. It's not complex in the way the Market East tunnel proposal is--that is, as an engineering challenge--but rather as an organizational one--that is, getting the right players at the table talking the right tones.

There are two, and exactly two, transportation elements to the Market East tunnel proposal; everything else is highly speculative land-use development claims. These are to (1) connect regional/high-speed service to Philadelphia International Airport, and (2) bypass Zoo Interlocking, which, for this proposal, is seen as one of the corridor's major pinch points.

My response to Zoo to begin with. It is true it is a pinch point, but a necessary one. There is no better way to provide a wye junction between the Northeast and Keystone Corridors, two high-speed lines, without egregious tunneling and investment. Much better, then, to simply optimize Zoo for 100 kph (~60 mph) traversal, particularly since one goes directly from it into the 30th St. yards and station throat.

Certain transit proponents claim Zoo traversal takes 45 minutes; this is demonstrably false: a much more accurate time penalty can be ascertained by comparing the commuter rail times from North Philadelphia to 30th Street and North Broad to Market East, respectively, to one another. This is approximately four minutes, and for local services; express trains can run the same route more quickly. The reality is that, for the fastest services (the Acela and Northeast Regionals), the time penalty is more like 45 seconds, and can be reduced to 30 with an optimized interlocking. Besides, there are improvements elsewhere on the corridors that can ameliorate Zoo's impact--switching to modern 25kV 60MHz constant-tension catenary (the most advanced currently available), for example, will effectively double speed limits throughout the corridor.

So, because (a) it's a junction between two high-speed lines, (b) no form of restructuring is economically feasible, and (c) far greater speed (and thus time) gains are available through a far less expensive project, I urge ignoring the, er, urge to bypass Zoo. Keeping structures like Zoo in place are one of the major compromises one has to make when implementing a high-speed system on top of an existing medium-speed one, as the Italians, French, Germans, Belgians, Dutch, Koreans, Russians, and (soon) British have all found out*.

The second problem this proposal purports to solve is bringing intercity rail to the Airport. The proposed route would break off the existing NEC in the Eddystone area, follow I-95 or the Chester Branch into the Airport area, provide a new station, and then delve under the Schuylkill and the tunnel, coming back out around Frankford Junction--but this is not really the most optimum way to bring passenger rail there.

The Chester Branch is arrow-straight. Don't be fooled by the SEPTA line, which comes off the NEC following the 52nd St. Branch and then curves onto the Chester Branch; look on Google Maps. It diverges from the NEC right under the Grays Ferry bridge and extends past the Airport with no noticeable curvature whatsoever. It continues this pattern, though now with minimal curvature to avoid geographic obstacles, all the way to Eddystone. SEPTA's line makes use of a part of this alignment, but to put it bluntly, it is about as tailored to high-speed rail as you're going to get. Ignoring it is thus foolhardy.

The big issue the Chester Branch has is its mixed traffic. This comes in two flavors: local traffic to Chester (well, duh) and through traffic using its uppermost mile as a cutoff linking the CSX (ex-B&O) main with the (ex-PRR) High Line; this latter section is pretty important for double-stacks originating from the Ports of Baltimore and Wilmington, particularly as the Charles Street Tunnel down in Baltimore and Fairmount Tunnel up here are too squat for them.

This is, however, mostly an organizational issue that can be solved with limited, but judicious, application of concrete (and concrete needed to provide grade separations, anyway). In this case, this involves (a) grade-separating the line through Essington and Tinicum--this will involve an aerial due to the shallow water table and Darby Creek crossing--as well as flying over Industrial Highway to meet the NEC (the existing freight line would be retained underneath this aerial), (b) re-activating the rather more circuitous 52nd St. Branch for freight traffic with a new junction with CSX about a football field north of the apex of the existing SEPTA flyover, a reactivation which would service industrial development along Essington Ave. and parts of the Industrial Hwy. near the Penrose Ave. bridge, and any potential Port expansion around the mouth of the Schuylkill, and (c) a double-deck railroad between the CSX line and the High Line, with the passenger section underneath and the freight section on top. At the NEC, the freight line would veer onto the High Line right-of-way and the passenger one would integrate with the NEC main via either flyovers or duckunders.

While this slate of improvements is not insignificant, keep in mind that the Essington/Tinicum aerial would be necessary anyway, due to the Darby Creek crossing, and that each improvement utilizes existing rights-of-way with technically minimalist solutions for handling passenger/freight traffic separation and the grade separation necessary for true high-speed rail. Costing isn't too hard: I do not believe double-stacks move along the Chester Branch and so undercutting shouldn't be necessary, and the two-level box structure between the NEC and CSX puts Plate K clearance (the double-stacks) up on the highest level. Total costs shouldn't be more than $100 million to $250 million.

There are significant operational advantages to this alignment. Firstly, trains not calling at the Airport can use the existing NEC alignment to bypass it completely, which means that the line can be (re)built to handle lower capacity than the tunnel proposal (which would shove all trains through the Airport station, whether they stopped there or not).

It also offers a new local alignment to Chester, allowing for stops at Tinicum and/or Essington, as well as 70th, 63rd, and Bartram's Gardens in the city. The Airport fishhook can then be repurposed into an AirTrain-type setup.

And finally, there are concrete land-development advantages.

Biggest of these is that the 52nd St. Branch alignment offers freight access to a large swampy area across the Schuylkill from the Navy Yard--an area which, with the completion of the current Port expansion (called Southport, I believe), will become the next logical place for a new Port terminal to handle growing Northeast port traffic. A natural terminus, it lies between a large industrial area and the Airport, and would make the Navy Yard a natural place to handle the Port's administrative (office) functions, lying, as it would, between two of Port's three largest termini.

More importantly for passengers, local stops can be leveraged for transit-oriented development. This is particularly useful around 63rd and 70th Sts. and Bartram's Garden.

Finally, with the speed boost from catenary modernization, PHL would lie about an hour from Midtown--the same time, coincidentally, that JFK is on the subway. Instead of attempting to use less and less tenable suburban airports to handle NYC's congestion, PHL's roomy international terminus can provide necessary space.

This is the alternative vision I have: Airport service provided along a natural corridor, Zoo improved inasmuch as is geometrically feasible, and none of that asinine Market East tunnel proposal--which, I may remind you, would be a bored tunnel through alluvial soil under the water table in a heavily-urbanized area, which can be read as f(x) = Extreme Cost Overruns. There is no way on this earth, or any other, that that project will cost "merely" $3 billion, as Amtrak is attempting to sell us on; peg it more between $10 and $15 billion, and that is at its technical cheapest: a 300%-500% cost increase.

By contrast, my proposal will add in reasonable intercity PHL service for $250 million (note m) on top of the flat cost of modernizing the NEC--that is, catenary conversion plus the costs of Gateway and the Great Circle tunnels under the Hudson and in Baltimore, respectively.
_______________
* The Japanese, Taiwanese, and Spanish high-speed networks are all of a completely different gauge standard than the existing systems, and so don't run into this issue. China, meanwhile, has the resources and attitude to ignore this issue.