~ part i ~
how savannah generates diversity
how savannah generates diversity
|Four-way intersections really do make an active city.|
Jarrett's vantage points have resonance with my experience. My formative travel and collective graduate school experience taught me that cities, even their forms, always find their sweet spots. The cultural endeavors of mankind (including languages and their products, written works) tend to have this inside quality. They serve their peculiar and diverse cultures in ways that are often hidden from direct observation. However, such observation is possible if you have the patience of a insider or a philologist. A philologist inspects form, the transmutation of words or their use, to tease out the cultural development of meaning. Observe the city well, Jane Jacobs (that philologist of urban form) suggested, and you will discover why many well-intentioned interventions mistranslate the city and often miss their mark. The underlying purpose of the grid, similarly, is to hit one of the sweet spots of cultural work that actually generates urban vitality. This work of the grid, like language itself, may be invisible at our scales of experience and to generational observation often. Such transmutable vitality of the bones is what Miss Jane called the inherent "diversity" of cities. She pointed out that local interventions into grid functions often frustrate the "generators of diversity", some of these traveling at the scales of time so slow they are epochal, and we just haven't taken notice of their dynamic economy. An undisturbed, well-connected grid will naturally advance and balance the simultaneous, diverse pulls of the urban economy. Savannah's Historic District form, more than any other grid I know, crystallizes this fact and, in fact, employs it to generate commercial and civic vitality in manner we can plainly read.
In fact, Savannah does this well and transparently, because, almost unique among cities, its historic fabric does not contain one grid, but two. The second major division in the Odonomy of Savannah's Historic District is the division between Savannah's two grids. The 3/4 mile x 3/4 mile Historic District is a composite grid created out of two overlapping grids. Understand the virtues of these two grids and you apprehend one of the generators of urban land use diversity in Savannah's grid. I call these complementary grids the "Fast Grid" and the "Slow Grid" due to the relative speed of vehicular traffic on them.
|Conceptual Map of Savannah's "Fast Grid"|
|Broughton Street, the "Main Street" of Savannah|
|A car stops for a cyclist on Drayton St. ..Is this any barrier to crossing?|
Since these primary Fast Grid streets (both loading streets and avenues) are the most heavily traveled by vehicles in the grid, the intersections of the Fast Grid streets represent the largest conflict points for vehicular travel. The majority of signalized intersections in Savannah (which, by the way, occur far fewer times per square mile than in a typical grid, like Charlotte's) are therefore at the four-way intersections of the Fast Grid streets. Since the Fast Grid loading streets usually have two to three extra traffic-controlled intersections to navigate across the grid and have lots of pedestrians and opposing turning movements to deal with at the intersections, these streets can stack appreciably and can congest at times. Because of the heavy east-west traffic volumes sometimes produced by the "cross-bay" traffic, they can present formidable challenges for pedestrian and bike crossing, and, at places, such travel along them. Thankfully, with the exception of Jones Street, they are given much attention in terms of traffic control. Only one of the streets, median-less Bay Street (at the top near the waterfront), represents persistent pedestrian and traffic problems around the clock. Bay Street is easily the greatest traffic deficit of Savannah's grid, especially since the right-of-way is very narrow for its volumes and much of the cross-bay and industrial/port trucking traffic is forced to route through this bottleneck. But many waterfront boulevards in touristy and busy port cities usually are a bit congested after all (and perhaps should be).
As I mentioned, all of the primary loading streets are given priority except for Jones Street. Avenue traffic does not stop anywhere for Jones Street. The fact that you only have only up to five potential stopping points, thus, between Bay Street and Gaston Street, the southern-most Historic District street, really makes travel on those avenues unhindered, especially as you move further south away from the most urbanized portion of the district near the waterfront. Despite covering the same rough distance (actually, a little bit greater distance) than the east-west Historic District streets, you can usually manage to travel the entire district from Bay to Gaston in a car during rush hour in about 3 minutes, by far the fastest average travel times I recorded among all of the grid's through streets. (Yes, I timed this in my car, keeping pace with the traffic, timing runs between 7:30-9:00 am and 4:30-6:30 pm on most of the district's through streets at least twice). In normal rush hour traffic, I was usually a full one to two minutes slower on the primary loading streets getting across the grid east-west from Broad Street to MLK. (See...These kinds of useful facts are what I wish people recorded somewhere about grids--hopefully, real-time GPS data might some day prove to be a boon for this kind of research.)
|Conceptual Map of Savannah's "Slow Grid"|
I like to think of the Fast Grid avenues as creating a "pressure drop" in the grid, pulling out traffic circulating in the Slow Grid, much as anteater snouts would suck termites out of a mound (or "java chips" through a straw...you pick your metaphor). The garden squares help this process by introducing centrifugal forces to vehicular traffic in the Slow Grid. They induce "high pressure" in the vehicular flow network. (Of course, some drivers like to travel in the "high pressure" zones nonetheless. They just like driving around the squares, enjoying the scenery. That's ok! Savannah gives them that option. You can be a slow poke in Savannah just fine. ...There are your slow grid people and your fast grid people everywhere, but, normally, they just don't travel separately.)
|Not really a barrier to pedestrian mobility (a T-intersection on a square)|
The garden squares and "low pressure" avenues exert two forces that create the land use diversity that is relatively evenly dispersed in Savannah's historic district:
|Along Drayton Street. ...A city in flux.|
2. Secondly, they pool pedestrian and slower traffic to the interior of the wards. The garden squares thus support amiable uses geared to attracting walking and more leisured traffic. They also invite the frontage of civic uses that are not always open around the clock, but, nonetheless, need a ceremonial front addressing a public place with foot traffic. The uses on the Trust Lots east and west of the gardens are therefore perfect for civic uses since they are tied directly to both kinds of traffic, creating a presence on both the Fast Grid avenues for the convenience of users and the Slow Grid squares for their ceremonial frontage.
|A corner use on Bull Street|
Because of its form, Savannah attracts a remarkable density of civic uses, but not even Savannah can support so many, so, where civic uses are less supportable, other uses, typically gorgeous Southern mansions, take their place on those prominent trust lots. The garden squares along Bull Street especially attract a high concentration of civic uses. Going away from Bull Street east to west, the garden square character progressively becomes more quiet. The squares on the perimeter form the communal heart of attractive little urban neighborhoods that, surely, still must preserve something of the original serene quality of Oglethorpe's early Savannah.
But the connection to Forsyth Park is not the only reason higher intensity uses concentrate on Bull Street and its squares. Simply, Bull Street is in the center. Uses in the center have more access to other uses and thus more users. Uses on the perimeter have less. Intensity of use steps higher in two directions in Savannah. Intensity steps higher going north towards the waterfront; this is the response to the pull of the attractive edge. And, intensity steps up going to the center in the east-west loading direction; this is the pull of centrality. So Savannah adapts to its regional shape, as well as its modular dynamics.
|SCAD saw low overhead in Savannah's old uses. The economic relationship reciprocated.|
Savannah's form, as one can hopefully begin to see here, provides simultaneous-countervailing centrifugal and centripetal pulls that ensure a distributed land use diversity, stepped in intensity and navigating transitions of use dictated by internal form, greater geography and a patterned but variegated transportation network. You can read Savannah like a book, and see stories within stories just walking square to square, without even needing to purchase a guidebook. You just need to learn her alphabet, her grammar and her thought patterns of time. For a primer on that language, here is a good starting point.