New Plans for Old Avenues in New York City

In its recent endorsement in the New York City mayoral race for sudden frontrunner Bill de Blasio, StreetsPAC cited de Blasio's street safety platform calling for "a city with zero fatalities or serious injuries caused by car crashes on the streets of New York." In addition to various law enforcement measures, including speed limit reductions, de Blasio's platform also calls for design-based changes, including "narrowing excessively wide streets that encourage reckless passing and speeding, widening sidewalks and medians to make streets easier and safer to cross, and adding dedicated bicycle infrastructure to create a safe space for New Yorkers on bikes."

Under Mayor Bloomberg, numerous design interventions of this sort have been carried out, and although some redesigns have brought significant transformations -- Times Square, for example, or the reworking of Grand Army Plaza in Brooklyn -- others have been little more than glorified patch jobs, taking common-sense but modest steps to address notoriously dangerous crossings and intersections without unduly interfering with the primacy of high-speed automobile circulation. While there has been abundant use of colorful paint to widen sidewalks and expand pedestrian plazas, and the wonderful addition of bike-sharing and new bike lanes, few streets have seen thorough overhauls that are consciously geared toward improving quality of life for those on foot rather than simply enhancing safety and mobility.

Incremental changes make sense as a general rule, but in a city like New York, surely there is room, and appetite, for at least one transformational street project?  However, certain major changes, such as wide-scale permanent pedestrianizations, have generally fallen out of favor since the 1970s, while the imaginations of some planners and architects can get carried away in impractical, overly-complex or even fantastical directions when presented with a large blank canvas to work on, as in the case of this fanciful example from last year's Greatest Grid exhibit, showing a Manhattan street repurposed for agriculture:

A more realistic plan is the "Yorkville Rambla," developed by John Massengale and Dover, Kohl & Partners, which would essentially pedestrianize the center lanes of Second Avenue. The plan is simple, elegant, and most importantly, draws on established design predecent shown to be successful in similar urban contexts. The design does not contemplate a complete pedestrianization, but on New York's avenues, due to the need for dedicated bus and bike lanes, this is not likely to be feasible:

Source: Massengale & Co. LLC, Dover, Kohl & Partners et al., via Urban Design Week 2011

The plan pays homage to Barcelona's renowned thoroughfare, but there are in fact successful examples from New York itself very similar to the proposed design. Here, for example, is Dag Hammarskjold Plaza, a city park nearby the United Nations complex which was completely reconstructed in the late 1990s. Although it is classified as a park, and is administered by the city's parks department, rather than the transportation department, when viewed in context of the adjacent 47th Street, it is clear that the so-called plaza is actually a classic urban promenade:

The plaza looking west, with 47th Street at right. Source: Old Urbanist

Its design is brilliantly simple in my opinion, incorporating a few basic principles:

• Pave, pave, pave. The surface of the promenade is largely covered with functional brick and stone pavers, minimizing maintenance while maximizing the area for human use (which includes weekly farmers' markets). There are few if any concessions to "green" or "landscape" urbanism: no berms, no bioswales, no stormwater filtration areas, and half the right of way is not given over to indigenous grasses or drought-resistant shrubs (there is, however, an adjacent garden, to the far left in the photo, although this is not integral to the design).
• People-oriented seating. Bench seating is simple and faces toward the promenade, not away from it or in random orientations. If "what attracts people most ... is other people," in William Whyte's words, this straightforward design is a great success.
• Green to the eye, not green on the ground. During summer, the promenade is luxuriantly green to due an abundance of trees (planted regularly and formally, not pseudo-naturalistically). However, these trees take up very little space at ground level, minimally interfering with use of the space. For me, this is the true mark of a successful green area ratio: maximizing visible greenery while minimizing the street-level square footage actually occupied by that greenery. Planted areas can enliven a very large space, but this should be done with care, and with thought given to what sort of use the space is likely to receive.

Another promising and perhaps even more feasible plan would restore Park Avenue approximately to its early 20th century configuration by widening its median, although the plan by SHoP shown here does put a lot of unusable green space on the ground:

Source: New York Observer.

This seemingly High Line-inspired use of plants to restrict the area available for human use (without adding much visual green -- note the ratio of visual tree area to plant area of about 5:1, though the plant area probably occupies 100x the ground area) seems to be characteristic of many contemporary plans, including one by SOM for the elevated roadways around Grand Central. If that is the cost of deriving political will and public support from the High Line's success, though, then it may be an acceptable trade-off after all.

Whatever the plans of the next mayoral administration, whether led by de Blasio or another candidate, one hopes that at least one street redesign such as these makes it onto the agenda. For a relatively modest cost, the benefits not only in safety but in quality of life would be substantial.

Related posts:

• Recivilization also features the Yorkville Rambla at a post here, and outlines a set of very similar principles (which I didn't see until after writing this -- showing that there may possibly be something to them!).
• At Strong Towns, Steve Stofka provides a thorough post on street design and the perception of street width, using the addictive new program Streetmix.

Greening the DC Zoning Code?

The newly released draft of Washington DC's zoning code, as reported by Greater Greater Washington, contains promising changes, including reduced parking requirements and the allowance, after a decades-long ban, of homes on alleys.  Also new to the code is the proposed "Green Area Ratio," a regulation that is molded on similar laws found in European cities such as Berlin and Malmo.  A version of the same idea, the so-called "Green Factor," has already been implemented in Seattle, where it has drawn praise and some criticism. 

The basic idea of the GAR is this: in order to address a perceived imbalance of paved/built to green space in urban areas, the zoning code must mandate dedicating a certain proportion of each lot to landscaping or permeable surfaces.

 According to its proponents, the GAR will push buildings to better treat stormwater, improve air quality and reduce urban "heat islands." However, the draft regulations do not appear to contain any standards to determine whether landscaping elements actually aid in stormwater retention or treatment. Nor is there information about whether the estimated benefits are large enough to matter regionally or city-wide.

Existing research also raises potential concerns that nobody will monitor the environmental performance of these features once built. George Washington University professor Melissa Keeley, whose work the draft documents cite, sounds a cautionary note about "policy deficits and the lack of adequate outcome monitoring" in her 2011 study of Berlin's green ratio.

Some of the benefits seem questionable, like the statistic that "1,000 square feet of green roof can supply 110 people with oxygen." While this is beneficial, that the carbon monoxide-emitting motor vehicle creates much more pollution in urban areas than the lack of landscaped surface.

Berlin's air quality, which some sources estimate is the cleanest in Europe, largely owes its success to car restriction zones and policies that encourage traveling by foot, bicycle and mass transit. Cities are unlikely to substantially improve air quality without confronting the role of the car.

Additionally, GAR does not appear to distinguish between non-green ground coverage. An asphalt-covered surface parking and a 10-story apartment building with no parking and which covers its entire lot both receive a GAR of zero. On the other hand, it appears that the same apartment building with a 160-car garage but with a green roof could earn a high GAR.

The most notable element of the GAR is, perhaps, what it does not include. Single-family homes receive a special exemption from the proposed regulations because, the hearing report states:

Implementing this standard would impose an undue financial and logistical burden upon homeowners. Properties with one-family dwellings typically maintain higher standards of landscaping and retain more green area.

Imposing expensive mandates on multifamily housing while exempting single-family homes from regulation creates a perverse outcome in which dense, space-efficient housing suffers penalties for being environmentally unfriendly, while low-density homes occupying a small portion of their lot enjoy rewards for "retaining more green area." While the GAR is compatible with high density urbanism, regulations which apply differently to various densities can make some types of housing more expensive, especially small apartment buildings.

The proponents of the New Urbanism, meanwhile, have been working to address stormwater management from an unapologetically pro-urban perspective, recently engaging the EPA in a discussion over existing stormwater standards that may inadvertently penalize density and enourage sprawling development.   Laurence Aurbach's article Dense and Beautiful Stormwater Management discusses these issues in depth, suggesting that planners and regulators accept density as a best management practice for stormwater.

Ultimately, certain landscape elements, green roofs and other innovations may have an important role to play in Washington, but residents deserve to learn more about the long-term costs and benefits of such a large scale, mandatory and relatively untested regulation before adopting it as part of the zoning overhaul.


In old cities, the highest art is often maximizing visible greenery while minimizing GAR. That creates streetscapes of intense greenery at low cost. The tools of this approach are not swales and rain gardens, as useful as these may be, but window boxes, hanging pots, climbing vines and clay urns:

Flickr/Ela2007

Eguisheim, Alsace

Taipei, Taiwan.

Flickr/Joanna_Young

Cagliari, Sardinia.

A "Verdict" On Landscape Urbanism?

The Landscape Urbanism movement has recently received a lot of attention in urban blogs (here, here and here, for example) as well as the mainstream press — much of it quite critical.   There soon may be at least one official verdict on Landscape Urbanist design, however, as a lawsuit is currently proceeding against the city of New York for negligent design of the High Line walkway, which allegedly caused the plaintiff, an elderly woman, to trip and fracture her ankle.

Source Here

At issue in the lawsuit are the peculiar concrete paving blocks, seen at right, which have a slightly upturned edge at path margins, and which taper off into raised, fork-like protrusions.  The purpose of this odd design feature?  In an essay by James Corner, the Landscape Urbanism proponent who was the lead designer for the project, a similar photo of the High Line is featured with the caption, "a view of hard and organic surfaces bleeding into one," which appears to tie into Landscape Urbanist ideas about breaking down the separateness of the agrarian and the urban.   Is it possible then that this design feature reflects purely aesthetic concerns?  The raised blocks, however, present a serious tripping hazard, according to Geoffrey Croft of NYC Park Advocates, one that should have been forseeable to designers of the $152 million project.

Having walked the High Line myself last September, my impression is that the blocks are a significant hazard, one which is magnified by the excessive narrowness of the pathways and the fact that pedestrians are understandably more interested in observing their surroundings than scrutinizing every step.  The staggered, uneven placement of the fork-like elements, as can be seen at upper right in the photo, almost seems designed to promote tripping and stumbling.  The city appears to have agreed, as the edges of the blocks are now awkwardly roped off, which adds a degree of safety but which destroys the "bleeding into one" aesthetic.