The 95 Question

In today's Metro, planning theorist and PlanPhilly head Harris Steinberg envisions burying I-95 along the Delaware Avenue waterfront from Washington to Spring Garden. Pragmatist and Deputy Mayor Rina Cutler (if you're reading this, I'm still looking for a job), on the other hand, has espoused a "rebuild-in-place" position whereby existing infrastructure gets renewed as need be, but no new far-reaching plan is espoused.

The forest I fear both are missing for the trees is that I-95 doesn't need to be there in the first place. The purpose for which it was originally designed--transporting goods to and fro along an active, pier-studded waterfront extending all the way from League Island to Torresdale--lapsed long ago with the containerization revolution and the implementation of the modern practice of concentrating port facilities in large terminal complexes. In terms of its original design concerns, it is obsolete. (This is true of most waterfront expressways.)

In terms of interstate travel, it is duplicative. There are no fewer than four different major routes between Baltimore and New York through the Philadelphia metropolitan area (to wit: I-476-PA TPK-NJ TPK, I-95, I-295, and the NJ TPK) via limited-access highways; travel time differences on three of them are, at best, limited. Yes, I-95 is a spinal Interstate--but it's because of this reason it should be routed around the city center instead of through it (as it is in D.C., Baltimore, and Boston).

I-5 in Seattle is also spinal (running essentially between Vancouver and Tijuana), but there is a strong debate there whether to bury it or eliminate it*. Arguments in favor of elimination are strong and applicable to the Philadelphia situation. Rerouting I-95 via either the Blue Route, I-295, or the NJ TPK (or, as I have suggested before, a combination of the latter two) would shift through traffic out onto the beltways instead of the urban core, thereby making closure and eventual (urban) redevelopment of the section from Oregon to Allegheny** feasible. Once you've closed the expressway, you've also gained redevelopment parcels, some which even come with ready-made basements, which in the long run will eventually destroy and reurbanize the gap between city and waterfront. This plan is also much cheaper than even Cutler's, since it would mostly constitute re-signing and bureaucratic transactions leading to the sale of developable parcels.

Current traffic along I-95 is split between through traffic (although the directness of the NJ TPK makes this not as much as you'd think, particularly southbound) and local traffic originating or terminating in Center City. Local traffic needs can be met, in the urban core, via good surface arteries, and I-95 happens to parallel one such: Delaware Avenue, which has been re-signed Columbus Boulevard through Center City and South Philadelphia. This road has plenty of capacity--especially when augmented by the grid--to pick up 95's slack.

To summarize: closure of I-95 through Center City Philadelphia would be (a) cheap and (b) productive in terms of releasing developable parcels in revitalized areas, as well as in terms of reuniting city and waterfront. The structure can also be reused for other purposes (one possibility that springs to mind, congestion issues aside, is an El spur) or simply auctioned off, the easement destroyed. Land clearance does not even have to happen  prior to conveyance--some plans may well find the existence of the deck a useful amenity for e.g. the provision of a roof, or postindustrial-grit ambiance, or even for parking. In fact, infrastructure clearance in certain segments--i.e., where I-95 is already sunken--is counterproductive in that it destroys existing amenitization, thereby undermining the land value, and reducing the amount recoverable through conveyance. Through traffic needs can be met by rerouting I-95, and local traffic, via Delaware Avenue (Columbus Boulevard), which parallels this easement most of the way along this corridor. In this way, redevelopment of infrastructure past can be used to meet urban needs of the future.
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* Presumably by rerouting it along current I-405 (eliminating that designation), extending I-90 to Tukwila, and re-designating the resulting spur from Lake Union to Lynnwood I-305.
** The Oregon terminus accesses Packer Terminal and Allegheny the Richmond Terminal. North of Allegheny the expressway would be re-designated as a spur road (possibly I-395? I-695? I-995?) to the juncture with current I-276, which may or may not be so designated in the new numbering scheme.

Sharing Space

In the past I've (blasély) talked about naked streets, or as they are more euphemistically known, shared space, mostly in the context of other work, such as understanding street hierarchies. Now I would like to offer a few suggestions on realizing shared space:

1. The essence of shared space is that the travel ways (carriageways or cartways) are shared between all modes. Very narrow streets in older cities are often naturally shared spaces.
2. The lone useful metric of success in measuring fully shared space is whether or not walking in the middle of the road feels comfortable and natural; this is because of pedestrians' tendency to favor sidewalks wherever feasible; when pedestrians can effectively lay a territorial claim to the middle of the road, the motorist's response must be to accommodate to the pedestrians' territory, rather than pedestrians being excluded from motorists' territory. The pragmatic application of this is that shared space forces a natural speed limit, for motorized transport, in the range of 15 mph or 20 kph. In other words, sharing space naturally caps design speed.

This is the theory. Not rocket science, is it? Now to some application guidelines.

3. There is a clear hierarchy of streets even within the shared space paradigm; this hierarchy manifests as the distinction between residential and commercial shared spaces. This is in part because commercial shared space can be a bit more forgiving than residential.

Let us now elaborate the design guidelines for what both types have in common.

4. The street is narrow to very narrow. In most North American settings, this narrowness can be accentuated with onstreet parking.
5. The street is unidirectional (one-way).
6. Buildings alongside shared spaces are close together and cluster on, or close to, the lot line.

Now, let's get on to what describes a residential shared space.

7. There is little, if any, differentiation between carriageway and non-carriageway on shared-space streets. A small "sidewalk" may still be allowable as a space for street furniture (such as stoops, benches, trash cans, or street trees), but this space should not extend further than 3 feet from the lot line: pedestrians will still favor sidewalks when the sidewalk is as narrow as 5 feet.
8. The street is rarely more than  35 feet wide, and is, indeed, frequently less.
9. There is almost always only one travel lane; this travel lane is usually 10 feet wide when it accommodates automobile traffic.
10. The street must be quiet, that is, with an AADT under 500.
11. Parking lane(s) can be provided on either side of the travel lane: shared spaces can thus vary in width from sub-10-foot (very rare) to about 35 feet (fairly rare). Because the cars are parked close to the lot line, there is little comfort space for pedestrians there, bringing them out into the middle of the road. Onstreet parking is often an excellent way to artificially narrow a road.
12. Residential shared spaces tend to break into three typologies: the 10-foot class, with only one lane and no onstreet parking; the 20-foot class, with one travel lane and one parking lane, and finally the 30-foot class, with one travel lane and a parking lane on either side.

Commercial shared spaces are a bit different.

13. Commercial shared space is different from residential primarily due to the presence of storefronts facing the street.
14. Where there is shared space with a parking lane and commercial facing one side of the street, the parking lane always goes on the other side.
15. Commercial shared  space can have deeper sidewalks: up to 10 feet, due to the importance of window-shopping in commerce. This is especially true where there is parking on both sides of the all-mode travel lane.
16. It may be the case that commercial shared space can handle multiple travel lanes (no more than two). However, if this is so, the travel lanes still must be unidirectional if side-by-side, and bidirectional if and only if the parking lane is provided between travel lanes, and that if there are two travel lanes, then there must be direct access from the sidewalk to the travel area on at least one side (i.e. no parking lane).
17. This necessarily means that commercial shared space can be no more than 50 feet wide in most cases, with the possibility of 60 foot in the extreme case of having two parking lanes sandwiched between the travel lanes.
18. Through-traffic not wishing to use the commercial street needs to have a bypass easily available. This is particularly important since space sharing in popular commercial areas is likely to massively depress AADT along that particular road.

From this discussion, I would like to suggest that good 30-foot typologies would be (a) storefront-sidewalk-travel-sidewalk-storefront or (b) storefront-sidewalk-all mode travel-onstreet parking-lot line (non-storefront); 40-foot, (a) storefront-sidewalk-travel-travel-sidewalk-storefront or (b) storefront-sidewalk-travel-parking-sidewalk-storefront; and 50-foot, (a) storefront-sidewalk-travel-travel-parking-sidewalk-storefront, (b) storefront-sidewalk-travel-parking-travel-sidewalk-storefront, or (c) storefront-sidewalk-parking-travel-parking-sidewalk-storefront. Commercial streets narrower than 30 ft. can also, of course, occur; indeed, at the narrowest widths, they would be busier versions of residential shared space. Madrid's Calle de Preciados is one such example.

Delineating shared space is my next topic. Of course, the best way would be by use of a concept I call materials assonance, where particular materials are used to define how such-and-such part of so-and-so street is supposed to behave. Belgian blocks, for example, could define parking areas, while brickwork defines through passages, and slate, areas where street furniture goes. But implementation of a materials assonance plan would take quite some time, and would likely be undercut by state DOTs' insistence on confusing streets with roads. In the interim, before materials-assonance plans can be tried out, I would suggest a simple paint sheme:

Sharrows are already being used to identify spaces shared by bikes and cars. If the sharrows itself is what is used to identify shared space, then why not take the concept one step further and use it to define where pedestrians have right-of-way as much as cars? Furthermore, bike shared space is included in pedestrian shared space, so this sharrows is even more general than the bike sharrows. Painting pedestrian sharrows at the entrances to shared-space networks would territorialize the interior of the network for the pedestrian, and over time, lay the ground work for areas to develop materials assonance schemes in.

Quick Thought

The difference between found and vernacular architectures is a translation into the built form of the difference between shelter and home.

Quick Note on the History of Urban Planning

Nostalgia* has been behind almost every movement in urban planning.

1. City Beautiful. Nostalgia for the imperial center, as established in Mesopotamian, Greek, and Roman precedent, and retranslated in the Baroque period.
2. Decongestion (for lack of a better word). Nostalgia for the idealized medieval free city. We can see this in Ebenezer Howard's Garden Cities of Tomorrow and especially in Lewis Mumford's The Culture of Cities.
3. New Urbanism. Nostalgia for the settlement pattern nebulously called "Small Town America". Resultant reduplication of features common to this settlement pattern, with the sole exception of abandonment of the strong grid. Outgrowth of urban theory of Andrés Duany and James Howard Kunstler; informed greatly by Christopher Alexander's A Pattern Language.
4. Landscape Urbanism. Nostalgia for Modernism, primarily as an interbellum movement. Led by Charles Waldheim and James Corner. Nostalgia for Frederick Law Olmsted and Le Corbusier.
5. Traditional Urbanism. (Why is it even on here? Because it's the most cogent response to New Urbanism there is, despite its lack of attention in intellectual circles.) Nostalgia for castle towns (for lack of a better term). Nostalgia for density. Articulated best by Charles Gardner and Nathan Lewis. Informed by Jane Jacobs. Desire to harness urban forces operative in e.g. informal settlements.

There are only three major urban theorists who I can think of who are members of no movement--two of whom are Jane Jacobs and Christopher Alexander--and it's precisely their work that has stayed most relevant through the years. This is frankly because both of their work starts by correctly identifying the problem of the city (a precious rarity in urban theory) and works from there. The third theorist is, of course, Le Corbusier, whose ideas (the Radiant City) have been, by and large, discredited.
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* By nostalgia I mean the idea of a historical urban form as the ideal urban form. There's nothing wrong with that--humanity has experimented with a variety of urbanisms throughout its history, and relatively few have failed. Charlie Gardner pointed out that he's trying not to romanticize, and a laissez-faire approach to urbanism should theoretically lead to a variety of urbanisms; one of my larger points, both in agreement and in contrast with him, is that there are a variety of good urbanisms. Of the schools I pointed out, traditional urbanism comes closest to reflecting this--possibly due to its youth.

Emergent Urbanism

A new focus is, well, emerging in my thinking: the idea of emergent urbanism*--that is, the tying of models of how cities behave (urbanism) to a descriptive framework of complex phenomena called emergence.

The reason for this comes out of my rereading of Jane Jacobs, particularly Death and Life, for school. Jacobs' argument in this text is actually exceedingly simple: urban growth and urban decay both occur in self-reinforcing feedback loops, due to cities' organized complexity (as far as I'm aware, Jacobs' use on pg. 432 is one of the first uses of this phrase in scientific thinking)--whereas the planning profession up to her time persisted in attempting to analyze the city in two-variable (e.g. Newtonian) terms. Since planners are bringing entirely the wrong sort of methodology to the table, Jacobs says, their solutions are inadvertently catalyzing negative feedback cycles**, and as such, the entire enterprise of planning in her day is doomed on the face of it to failure***.

This critique has been such a powerful critique that it has resulted in a crisis of confidence among planners, and repeated attempts to re-analyze and re-think Jane Jacobs (usually presented as using new evidence to challenge her). Unfortunately for them, it's almost always easier to think of such new phenomena in Jacobean terms (gentrification, for example, as a particular subset of unslumming), and usually emergently. Once one begins to utilize a methodology based on feedback cycles, such emergent phenomena will crop up^.

So the question turns to: what is emergence? Emergence is most abstractly defined as "the way complex systems and patterns arise out of a multiplicity of simple interactions", as it is on Wikipedia. In other words: the perfect description of a city. It is the phenomenon that is colloquially referred to when someone references the "butterfly effect". It is the major outgrowth of the complexity theory that first arose in the information sciences, and repackaged via chaos theory into the overarching framework of non-linear dynamics (a phrase with two meanings: as a pure mathematical theory, and conversely as a way of describing complex systems, via the identification and analysis of feedback cycles and their catalysts and suppressants).

Jane Jacobs very definitely understands the structure of complexity, but since the technical language was in its infancy at the time Death and Life was written, she had no access to the language of complexity. As this language matured, however, it found its way into her later work; similarly, an early inflection of it influenced Alexander's Pattern Language--and it is due to this source in complexity theory that these two books retain their living vitality and intrinsic accuracy.

So what's the problem? Why are academic urban planners so desperate to disown Jacobs? Why do they always have to "rethink" her and attempt to frame more recently understood phenomenon in a way as detrimental as possible to her? Maybe it's because they don't like her theory? A great deal of urban planning--although not the type of planning literature I tend to read or think about--draws from sociology, and one of the things I've noticed about sociologists is the deep distrust they have of any ideas that didn't originate in their field^^--a distrust which seems to extend to adopting a confrontational stance when a good idea comes out (which should be relevant to them) they didn't think of. But ideas like complexity theory are good ideas which are now being studied and debated across a variety of fields--physics, meteorology, biology, information science, information theory, etc.--and are even being applied in very definitely sociological contexts, such as attempting to explain the architectures of Web 2.0. Yet there is undeniable resistance to applying them to the problem of the city: why? There is especially the dogmatic cant I hear in my school's sociological department: "Jacobs just has a collection of anecdotes: there is no theory". Bullshit. Anecdotes are the foundation of any good theory, and counter-anecdotal theory (like phlogiston) tends to be thrown out the window real fast. Jacobs has the evidence gathered from the street, and has the framework for explaining it. She has a theory in Death and Life--albeit one as basic as the field whose terms the theory would be best explained in at the time she wrote it; it is telling that the theory changed as she expanded on it and applied it to additional fields (although its structure did not) through later works like The Economy of Cities and Cities and the Wealth of Nations^^^, and her rather pessimistically-named last work The Fall of the West.

But the evidence of reality weights on her side. In my last post, I talked about the fallacy of naming all informal settlements "slums", and how there are in fact aspects of improving informal settlements (I talked about built form evidence; there is also (were the academics not so blind!) sociological evidence, economic*^ evidence, historical evidence**^, and so on) very different from those of true slums. This is a perfect example of emergent urbanism creating a community, and is part and parcel of emergent phenomenon referring to the redevelopment of already-settled areas, such as what Jacobs and most developed-world urban theorists concentrate on*^^. Today's urban phenomena, like yesterday's, like tomorrow's, are best explained in the framework of complexity theory and emergence Jacobs first showed us the way towards--someday I hope we as a whole can internalize this to the point where we can use her framework to supersede her, like biologists have done to Darwin; unfortunately, as long as the academic community stands in her way instead of embracing her, and the best ideas in urban thinking come from fields very definitely far afield of urban studies, this will not happen.
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* Yes, there was a blog dedicated to this sort of thing. I wasn't the first and I certainly won't be the last to discover and understand this reading. But do an academic search for "Jane Jacobs" and "emergence"  and you'll be lucky if you find one thing. A minorly famous (he'll certainly disagree with me on this) philosopher, Prof. Lewis Gordon, has a term for this sort of thing: disciplinary decadence, and it's frankly rife all over the social sciences.
** As already noted, the language of complexity theory was (at best) barely in a formative stage when Death and Life was written (much less published!); as such, Jacobs had no access to the terminology I'm using, and tended to use the terms virtuous circle and vicious circle for what we would today call positive and negative feedback loops (or cycles); virtuous and vicious being freighted, as they are, with unnecessary moral weight.
***I'd go a step further and say that the urban planning of the era, freighted by the prescriptive mentality of its intellectual heritage (Ebenezer Howard, Daniel Burnham, etc.)--grown out of the desire to reform cities more than describe them, and thusly (in e.g. Lewis Mumford's Culture of Cities--witness the extremes of what he calls "slums", and the way he attempts to rationalize what is on the face of it a reductio ad absurdum) morally weighting their descriptive elements of cities to an exorbitant degree. (Another way to look at it: urban planning is a nostalgic discipline; Howard, Mumford, and even Andrés Duany, the best urban thinker going, all look to the past for inspiration.)
^ This has particular relevance when parsing Glazer's Triumph of Cities. Glazer mentions therein he thinks Jacobs is in error, yet at the same time that  text's strongest argument, and major intellectual contribution, is the presentation of a solid case for the role of education in the feedback structure of cities! Disciplinary decadence at its finest, folks.
^^ Which is to say, most all of them.
^^^ ...They're on my to-read list (much like Proust and Pynchon).
*^ My chief grievance against economics is their devotion to the myth of symmetry. Economics models have to balance for no better reason than math has to balance, and thus a mathematical artifact has been elevated to a "basic premise" of economics models. The reality is, of course, much messier.*
* That said, I agree with the Keynesian concepts of the government as the employer of last resort and the need for government to generate stimulus and create jobs when the private sector is unwilling or unable to; particularly since the (non-Keynesian) way we're going about our recession today is clearly not working.
**^ In the form of the layout of premodern cities viz. that of informal communities. See, for example, the street network of Matera, Italy, Córdoba, Spain, Porto, Portugal, Frankfurt, Germany, or Manchester, England v. Rocinha, Rio de Janeiro, Brazil, Villa 31, Buenos Aires, Argentina, or Ankara, Turkey. Stable informal communities are little different than traditional urban cores in the developed world.
*^^ Mike Davis is the exception to this rule. Unfortunately, his Mumfordian style does just as much harm as good (much like Mumford himself).

Unplanned Urbanism

Or: A Problem That's Not Really A Problem

One of the great stories--and academic problems--of recent years has been the explosion of shanty, or squatters', settlements on the urban periphery in the developing world. Shantytowns are thought of as problems in much the same way--and for many of the same reasons--slums were in the late Victorian period.

Wealth-building in South Africa. View of improved section of Soweto. Cf. picture at bottom of post.

Don't get me wrong: oftentimes the conditions in such places really are appalling. Services taken for granted in the developed world, such as water and sanitation, are in many places nonexistent; and the housing stock is very ad hoc, temporary, and unsafe, being built out of scraps like plywood and corrugated metal.

A "campamento" in Chile, presumably in the suburbs of Santiago.

But at the same time, there is a whiff of antiurban sentiment about them: since they all are, of a technicality, developed initially from various forms of informal housing*, the stereotype is that they are all like Kibera in Nairobi. The reality is something else.

Rocinha, Rio de Janeiro, Brazil

There seem to be two major kinds of informal housing: true slums, like Kibera, where, despite many years of settlement, the economy is subsistence--where residents relocate upon success, spawning a negative economic feedback cycle--and what could simply be thought of, and referred to, as informal development--where wealth is being generated**, such as what is seen in Turkey, Brazil, or Indonesia, particularly evident in neighborhoods such as Rio's Rocinha.

Ankara gecekondular

In most cases, when wealth is being generated in the community, such as in Rocinha, improvements in the built form take place. Where temporary materials such as cardboard and corrugation were once the dominant structural material, more permanent constructions, typically of cinder block decorated in local vernacular, take hold. These structures are reasonably structurally sound; the average structure in the Turkish gecekondu***, for instance, has about the same structural strength as an American dingbat.

Villa 31, Buenos Aires, Argentina

One way of framing this distinction is by stating it terms of found versus vernacular architecture: a subtle distinction, for sure, but generally more work goes into vernacular architecture than into found architecture, and thus propagation of a vernacular is evidence of a move towards comfort in addition to the need for pure shelter...in other words, the ability to afford comfort. Comparison of Brazilian favelas and Turkish gecekondular against Kibera or "unimproved" (and thus still shantytown) parts of South African townships, such as Khayelitsha, demonstrate this basic dichotomy; again, Argentine villas miserias, such as Buenos Aires' Villa 31 (shown above), show a greater level of comfort and dignity than e.g. shack sections of Soweto^ (shown below).

A true slum: shack dwellings in Soweto, South Africa.

Let me end this post by getting to the point:  many so-called "slums" are actually spontaneously unslumming examples of emergent, everyday, or traditional urbanism; they are live communities where wealth-building is occurring. In other words, they are not slums, but rather emergent neighborhoods that need to be nurtured--not cleared.
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* In Planet of Slums, Mike Davis points out how occupation-and-squatting tactics employed in the initial development of many of these areas has been since superseded by a variety of other informal tactics.
** As opposed to the true slum, where the lack of generation of wealth (equity, often, in U.S. parlance) over the long term is a key economic attribute.
*** Pronounced gay-gee-con-do. "C" has a J sound in Turkish (which goes a long way towards explaining why Azerbaijan has a "c" instead of "j" in Azeri--a language closely related to Turkish). The word is a compound word meaning "built by night" or "built overnight"; the plural is gecekondular, with the addition of a syllable that is spectacularly impossible for East Asians to pronounce (r and l are assonant phonemes in most East Asian tongues, and assonant in a way that is precisely opposite the pronunciation of -lar).
^ The history of South African townships is actually an interesting topic (albeit one for another day). Suffice it to say right now that Soweto actually happens to be one of the wealthier historically-black townships in South Africa; a better example of true slum informal settlement on a large scale is Cape Town's Khayelitsha.

Costing the City Branch Line

Long ago, I suggested the possibility of a long-term subway line running from 8th/Oregon (Pennsport) to Ridge/Henry (Andorra), the first phase of which would run between 8th/Market and Girard via the City Branch cut and part of the Ridge Avenue Spur. It looks like this.

A very old map. For one thing, my station naming principles have changed since.

The next obvious question is, how much does it cost? Actually, answering this question is substantially more advantageous than other potential heavy rail lines (or even Phase Is of lines), as the routing proposed runs along a former (abandoned?) freight right-of-way in heavily redeveloped (or redeveloping) areas where industrial uses are obsolescent: Franklin Town* and Callowhill. People live--not work--in these areas today.

This routing has four key components:
-The Philadelphia Branch from Girard to Noble. This follows the last mile or so of what was once the B&O's Philadelphia mainline, and is parallel to the single-track CSX main on what is at least a four-track (possibly six-track) right-of-way. It also includes a 1/3-mile section in the Fairmount tunnel, between Noble and Park portals.
-The City Branch, along the former course of Noble St. between Broad and the Noble portal, just west of 22nd. Like the ex-B&O ROW, this is a very wide route that is in disuse due to the postindustrial evaporation of its customer base. East of Broad, the City Branch continues on an elevated structure to connect into the 9th St. Branch and the approach to the former Reading Terminal. This elevated structure network (extant from Vine to Fairmount, and from 9th to 13th) is now known as the Reading Viaduct.
-A new tunnel from Broad, along Noble, to an at-grade (no flyunder) junction with the Ridge Avenue spur between 10th and 11th Sts. This tunnel would include a new Callowhill station between 11th and 12th Sts. and a short stretch of 4% grade in order to clear under 13th and between Broad and the existing subway tunnel and portal onto the City Branch's former elevation.
-The Ridge Spur from Noble south to 8th and Market.

Acquisition of the existing parts of this right-of-way is the initial hurdle: CSX is infamously recalcitrant when it comes to giving away parts of its right-of-way. However, there is little economic justification for holding onto this stretch, as the Fairmount Tunnel has been single-tracked to maximize clearance**, particularly due to the ancient (and constraining) south portal, just under the proposed Paine Park site, the duplication with the double-stack clearing ex-PRR High Line trestle across the river, and the single-track bottleneck of a concrete-lined cut by Wayne Jct.; the lack of any active customer in the immediate area; and finally the slow speed limit of this stretch caused not by engineering so much as the sheer congestion encountered in an urban area--particularly the approaches to the Schuylkill Banks. However, as the Banks themselves have proven, CSX is willing to let go of obsolescent stretches of its right-of-way***, and a good deal of the right-of-way width between Fairmount Tunnel and Fairmount Jct. is nothing if not obsolescent.

Procurement of (portions of) the existing railroad easement, wherever not already in the public realm, is thus the first major expense this project encounters. Mercifully, however, it is short: one mile along an obsolescent section of an active right-of-way, and two-thirds of one along an inactive one. $30 million for acquisition costs seems like a reasonable estimate.

Since the meat of the project is basically the linking two separate railroad rights-of-way together, the greatest cost would be expected to be in the actual interlinking itself, especially one that (a) is underground and (b) requires engineering with finesse. While tunnel construction should be (for the most part) cheaply done via cut-and-cover, due in part to the lack of major commercial or residential uses along the vast majority of the 3.5-block-long section, it would also have to be built under 13th, into the Branch between Broad's street grade and its subway grade, and with a gallery area for the Callowhill subway stop between 11th and 12th^, would be done for close to the minimum possible cost of a true subway under U.S. labor conditions--but it is still a subway, and may well breach the water table when it passes under 13th, and thus will be expensive. $50 million sounds like a reasonable cost estimate^^.

The final major expense is what could be best called "installation of railroad technology", namely, the rails and ties, equipment, third rail, platforms, platform access, and turnstiles. Since I'm attempting to utilize the most cost-effective possible alignment, most further savings (howsoever incremental on an individual basis) can be made in this arena. For instance, the cars currently in use on the Broad-Ridge Spur would be re-assigned for this line. No new equipment = $40 million cost savings. Platforms would be 100 feet long, or just about the length of two BSL subway cars (why would they need to be longer?) and built out of wood, wherever feasible (Broad, Franklin Town Park, Rodin Museum, Lemon Hill, Girard), offering a cost savings of a few million. Instead of needing to install an expensive new ventilation system in the Fairmount tunnel in order to deal with the diesel fumes, the CSX section would be simply walled off from the rapid transit section, and the two tunnel sections would alternate between the existing ventilation shafts (which were originally engineered for the significantly greater emissions of steam traction). Few barriers are as effective as physical barriers, anyway. Cost savings: Quite a lot.

While an elevator (or two) would have to be installed at Callowhill, Fairmount, and Art Museum each--due to these stations' being underground--at all of the other stations, a pedestrian ramp (also made of wood) would be able to satisfy ADA requirements.

So there are essentially three elements that spending actually has to be done on to finish this project: (1) extending the track down our fresh new ROW, along with the third rail needed to power our equipment, (2) building a cinder block wall down the middle of Fairmount Tunnel to divide diesel and metro ventilation districts (and the masons would be used to build the Fairmount and Art Museum station platforms too)--the tunnel being shallow enough that approximately 1/2 of the current ventilation shafts should allow acceptable air exchange--and (3) installing wood platforms at all of the other stations. Where the ROW parallels the CSX line, a chain-link fence is also a must-install, but that should frankly be about the same as what an exurban homeowner would expect to spend at the Home Depot to completely fence a two-acre lot in. Perimeters rake up mileage real quick. I recall that laying track costs about a million per mile, so we'll cost this at about $10 million and give the masons and carpenters $4.5 million each to play with.

The final cost is a contingency fund, a hedge or allotment set aside to deal with unexpected expenses. This is usually about 10% of the project's total projected cost, which at this point would be $9 million ((50+30+10)/10); since we are already costing out with a tight cost ceiling, we'll give this contingency fund an extra mil, and make the total cost projection $100 million even.

$100 million is borderline for Small Starts (unusual for heavy rail projects; Small Starts as a grant mechanism favors light rail and commuter rail), and since we're aiming for about 10,000 daily riders (~1,111 riders/station)--not too bad considering that the combined population of the Census tracts immediately abutting this proposed line is 27,344, and thus fully in line with relative ridership on heavy rail lines in similarly dense areas in New York, Boston, Chicago, and Washington, D.C. At these (optimistic) projections, the cost per mile is $33 million, and per passenger, $10,000. Even if half the proposed ridership is actually attained, the cost per rider would be $20,000, still extremely low by heavy rail standards and well in line with light rail standards.

Sometime in the near future I hope to dwell on non-financial justifications for this line's existence and programs that SEPTA can run in concert with lineside destinations to increase usage.
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* Fun fact: The Baldwin Locomotive Works, the biggest American steam locomotive builder, was once located in Franklin Town, running between Callowhill and Spring Garden and Broad and ca. 20th. This helps explain the paucity of historical rowhomes in the area.
** Like the Howard Street Tunnel in Baltimore.
*** To my knowledge, the B&O easement originally extended to the river. Part of the Banks is, for example, built over 24th St. Sta.'s coach yard.
^ With the expectation of, if not a wholesale plan for, redevelopment of what is currently a transformer array in the station's immediate area--an array that is supposedly being replaced by a new one along the former Viaduct; such station-side development tends to greatly improve ridership.
^^ Based on the assumption that a mile of subway costs $100 million (a number I've heard thrown around for the Navy Yard extension) and considering that the actual tunnel length will be just shy of half a mile, with a bit extra thrown in for a cost cushion; an electrical substation, for example, may need to be built out by Girard somewhere.