Tag Archives: Philadelphia

Building Height and Density in Center City Philadelphia

With a hat tip to this tweet from John Ricco, linking to this compendium of tall buildings in Center City Philadelphia from the Philadelphia City Planning Commission. The document provides a brief profile of each building, showing building height, site size, gross floor area, floor area ratio, year of completion, and floor count.

Example of information from the Philadelphia FAR catalog. Screenshot from the document.

Example of information from the Philadelphia FAR catalog. Screenshot from the document.

Pulling the data into a spreadsheet allows for some quick charts to show the relationship between building height and density.

Height v density

It’s generally true that taller buildings are more dense, but not universally so. Buildings with the same density come in different shapes. Both the Liberty Place complex and the 230 South Broad St have an FAR of ~19.5; but Liberty Place includes a 960′ and 783′ tall towers. 230 South Broad St is just 250′ tall, but the building’s floorplates occupy 100% of the site.

By comparison, the densest zoning in DC is for 12 FAR (the C-5 zone), located in one of the few exception areas for DC’s height limit (allowing 160′ tall buildings along some blocks of Pennsylvania Ave NW). Quite a few blocks are zoned for up to 10 FAR, but nothing in DC can be built to an FAR of 15, 20 or 25, as in Philadelphia.

Considering DC’s effective downtown height limit of 110′ to 130′ combined with a maximum FAR of 10, it’s not hard to understand why DC has so many boxy buildings forced to occupy entire parcels. Likewise, DC’s height limit is indeed a hard limit on office density. Beyond 10 FAR, any additional density requires more height than the law currently allows.

In New York, the Empire State Building has a FAR of about 28. At less than half the height, the Equitable Building (inspiration for New York’s 1916 zoning code) has a FAR of 30.

Note: almost all of these very dense buildings are offices.

Back in Philadelphia, a more obvious example: the obvious relationship between building height and floor count (taller buildings have more floors).

Height v floors

Looking at building height by decade, you can see the clear trend of taller buildings emerging following the end of Philadelphia’s ‘gentleman’s agreement’ on building height – that no building should be taller than the Statue of William Penn atop the City Hall clocktower. This agreement left plenty of room for tall buildings; at 548 feet tall, City Hall was the tallest building in the world between 1901-1908. The agreement was breached by the construction of 1 Liberty Place in 1987.

Height by decade

This particular data set doesn’t include any buildings shorter than the City Hall tower; it’s not a complete record of all construction in Center City, just high rise buildings (the document was published in 2010). You can clearly see the approximate 500′ limit prior to 1987.

If you put all of these characteristics into one chart, you get something like this:

height GFA FAR year

The size of the circles indicate the gross floor area of the project.

A visual survey of selected elevated rail viaducts: part 3 – Els that gave Els a bad name

For more, see the series prologue, part 1, and part 2

A look at some of the Els that gave Els a bad name:

Chicago: The city’s rapid transit system’s elevated lines are ubiquitous; the system is named for them. In the Loop, the Els run above city streets. In other parts, some Els run above alleyways or private rights of way, away from streets:

Chicago El over an alley. Photo by author.

Chicago El over an alley. Photo by author.

Under the Chicago El. Photo by the author.

Under the Chicago El. Photo by the author.

Chicago El 1

Intersection of Wells and Lake in Chicago. Image from Google Streetview.

Owing to both the size of the structure, the relatively narrow streets, and the enclosure provided by the buildings, the Els loom over Chicago’s streets.

Adams/Wabash Station. Image from Google Streetview.

Adams/Wabash Station. Image from Google Streetview.

To be fair, most of these Streetview images are from directly under the structures, while many of the others are views from the side. Part of this is due to the street width, and part due to the buildings fronting the street. If you were looking for examples of suitable elevated viaducts for retrofitting suburbia, or for less dense urban neighborhoods, this isn’t a great example. Nonetheless, as noisy and obstructive as the Els can be, you can still find light and air above the sidewalks:

Intersection of Monroe and Wabash, Chicago IL. Image from Google Streetview.

Intersection of Monroe and Wabash, Chicago IL. Image from Google Streetview.

Philadelphia: The number of American cities with legacy heavy rail transit systems (meaning pre-war) is fairly limited (Boston, New York, Chicago, and Philadelphia). Over the last decade, Philadelphia reconstructed most of the Market St elevated, replacing Chicago-style structures with a single pier supporting a steel structure:

Market St El, prior to reconstruction, CC image from connery.cepeda

Market St El, prior to reconstruction, CC image from connery.cepeda

Market El, reconstructed:

Finishing work on the reconstructed El. Image from Google Streetview.

Finishing work on the reconstructed El. Image from Google Streetview.

On the other side of Center City, the El above Front Street almost reaches from building face to building face along Philadelphia’s narrow streets:

Elevated rail above Front St. Image from Google Streetview.

Elevated rail above Front St. Image from Google Streetview.

Boston: Much of the post-war transit investment in Boston focused on re-arranging infrastructure, tearing down Els and replacing those lines with subways. Few elevated sections remain, such as this portion of the Green line near Lechmere Station:

Green Line El near Lechmere Station. Image from Google Streetview.

Green Line El near Lechmere Station. Image from Google Streetview.

Perhaps the only reason this portion survives is because it’s directly attached to a river crossing:

Aerial view of Boston from Google Maps.

Aerial view of Boston from Google Maps.

Table of contents:

Parking, misunderstood

CC image from Atomic Taco

Let’s take a trip up and down the Northeast Corridor and look at recent parking news.  All three show some misunderstandings about parking, cities, and markets. Time for some Shoup reading assignments!

New York:  Looking to discuss changes to the zoning code parking requirements in downtown Brooklyn, the New York Times comes down with a severe case of windshield-itis:

In traffic-clogged New York City, where parking spaces are coveted like the rarest of treasures, an excess of parking spaces might seem like an urban planner’s dream.

Yet city officials, developers and transit advocates say that in Downtown Brooklyn, there is this most unusual of parking problems: There is simply too much of it.

Admittedly, many urban planning principles seem counter-intuitive at first glance.  When you add in the challenge of altering a regulatory status quo (such as modestly changing the zoning code, as is proposed in Brooklyn), the weight of conventional wisdom is enormous.

Still, it’s interesting to see a parking glut framed as an “urban planner’s dream.’ (particularly when compared against later articles from DC) It’s sure not my dream, either in terms of result (excess parking) or process (via the unintended consequences of regulation).  Building parking is expensive, so we don’t want to build too much of it.  Requiring us to build too much means that those costs just get passed along to the rest of us.

It’s worth noting that New York is not proposing to eliminate these requirements and rely on the market to determine how much parking to provide, they are merely reducing the requirement from mandating 40% of new units have spaces (in a neighborhood where only 22% of households own cars!) to 20%. Why not reduce it to zero?

Likewise, there are likely opportunities for new developments to make use of the excess parking already built. Hopefully, those kinds of arrangements would allow for new buildings to still be parking-free if the market so desires.  Nevertheless, a reduction in the requirement is moving in the right direction.

Philadelphia: A few miles south on the NEC, Philadelphia might be backtracking on parking, rather than moving in the right direction. Philly has already altered their zoning code to eliminate parking requirements in the city’s dense rowhouse neighborhoods.  Now, members of the city council want to roll those changes back. The council’s interference in a code change that’s only been in effect for a few months is troubling, as is the lack of reasoning.  From the Inquirer’s article on the topic:

“Most developers wish that they didn’t have to get approvals from anybody,” says Clarke. “I have to be responsive to the needs of the residents. They don’t have enough parking.”

Perhaps this is where a dose of that counter-intuitive planning wisdom would be useful.

The reasoning put forth for changing the rules back is equally troubling, particularly given the Philadelphia Planning Commission’s charge in rewriting the zoning code: reduce the need to grant so many variances.  Attempting to graft a comprehensive zoning ordinance onto a pre-existing (and pre-automobile) cityscape is bound to be a challenge no matter what; but pushing a code to require elements so geometrically opposed to the pre-code fabric is foolhardy.  Such changes, often made in the name of providing more parking only end up inducing unintended consequences.  From the Next American City article:

Gladstein said the bill’s proposed changes could set Philadelphia back on the path back to when the city issued more variances than nearly any other big city in America because of unrealistic demands in the zoning code.

“There are many instances in rowhome neighborhoods where you simply cannot provide parking by right because of factors like narrow lot lines,” she said. “We thought these changes would send too many cases to the zoning board.”

Gladstein also noted that lack of a parking requirement in the original code was intentional, as on-site parking, which often manifests itself as a front-loading garage, actually diminishes the supply of public parking spaces.

A code that doesn’t respect geometry, doesn’t reflect the city’s history, and achieve its stated goals is a bad code. Here’s to hoping those changes do not go into effect.

DC: In the District, the parking conversations aren’t focused on zoning (yet! – but they will be, and soon), but rather the management of on-street parking spaces. Policy changes take a different tack than in Philadelphia – instead of providing parking for residents via zoning code requirements, the city is strengthening on-street protections for residents with parking permits.

The reaction is all over the map – Ward 1 Councilmember says this is about a future that “discourages car ownership,” yet the goal of enhanced residential permit parking protections is about “striking a balance in favor of those who are residents with stickers who paid for them.”  Did those residents pay enough for a scarce resource?  If the price reflected the scarcity of spaces, would there be as much of a parking problem?  And how does making on-street parking for residents easier discourage car ownership?

Other elements of the Post parking article talk about the difficulty of parking for non-residents visiting the city, as well as the city’s efforts to re-purpose some curb space away from parking and towards other uses (such as protected bicycle lanes) – but fall into the trap of equating all things parking together.  Metered, permitted, for residents, for visitors, using curb space for parking or for other uses – these are all big differences, and conflating them all together is problematic, and increases the chances of misunderstanding.