“Even when a major border has concentrated city intensity, as in (San Francisco and Manhattan’s respective waterfronts), the zone along the border itself seldom reflects that intensity, or garners a fair share of it.”
Why is that?
In chapter 14 of D&L, Jacobs goes to great pains to discuss what she calls the “curse of border vacuums” but does little to differentiate the types of border vacuums that exist and how some may be more or less harmful than others.
For example: Water is – admittedly, arguably – the single most influencing factor on how, where, why, and when cities are conceived. It’s kinda like the new year’s champagne that results in a newborn son or daughter nine months later; one often follows the other. We can’t ignore it.
Trouble is, not all city-bearing water is the same. There are waterfront cities (those on lakes, seas and oceans), there are riverfront cities (those on rivers), and there are hybrids.
Jacobs doesn’t make that differentiation which is problematic because the geometry of each causes a significantly different impact on the quality of urbanism found there.
So long as political or topographical boundaries and policies don’t interfere (which is no guarantee), cities tend to grow outward in a radial, circular pattern. To invoke that awfullest of clichés – they grow like concentric circles emanating outwards from a stone tossed into water.
It makes sense.
As the genesis point of any city will likely evolve into that city’s historic centre and central business district, the radial growth pattern ensures that every stage of growth allows all people within that new growth stage to have a reasonably similar level of access to the heart of the city – notwithstanding, again, political or topographical boundaries.
In this way, a city grows gravitationally with an ever-increasingly dense core. And most importantly: Access to the core is possible from nearly 360˚. The importance of this cannot be overstated. When access to the core is possible from nearly 360˚, that implicitly means more people are located closer to the core than in any other given situation.
To reiterate: That doesn’t necessarily mean there are more people, but it means that more people are closer to the core.
It also implies that a diverse movement through the core from a variety of directions and vectors will also be maximized. This is why riverfront borders present few problems for cities. Assuming they’ve been properly designed and populated, the river is not a border but the centerpiece of a downtown.
One is unlikely to ever hear someone complain about Paris’ Seine River as a border vacuum. Ditto the Thames.
But a waterfront city is faced with the challenge of a gravitational growth model that’s half-neutered. A waterfront (for simplicity’s sake) chops a city’s natural circular form into a half-moon. That forces populations to arrange themselves in such a way that, while taking up the same amount of space as a non-waterfront city would, travel distances to the civic core are dramatically increased for large numbers of people and trips are generated from dramatically fewer directions.
That last item is essential: Waterfronts have naturally fewer points of entry than any other urban feature because a waterfront isn’t a border, it’s a terminus. It is the longest long block you can find. Imagine the urban space directly next to a waterfront as a park, and consider my previous discussion of permeability, portals and paths and you quickly understand why waterfronts so often struggle.
That struggle is perhaps most intense in a winter city.
For whatever reason cities around the world have adopted the default response of transforming their waterfronts into urban playgrounds and parks. Which is wonderful – if you live in a city where outdoor activity is enjoyable year round. Otherwise, it’s a deeply inefficient waste.
This default activity may be effective in warm weather climates like Rio de Janeiro or Barcelona, but utterly ineffective in places like Toronto or Chicago.
We may be fond of describing our waterfronts in such trite terminologies as being our city’s “front yard,” but it’s important to point out that when it’s -15˚ outside with 2 feet of snow on the ground most of us can’t even be bothered to shovel our own front yard, let alone play in it.
Why then do city planners and designers assume we’re going to travel to and use their front yard?
To understand the curse of a border vacuum, you have to understand the geometry of the problem. Like rivers, any long and narrow border is easily combatted by increasing connectivity and cross-pollination of uses between the two sides of the borders.
One does this through careful and intentional design interventions that overwhelm the border itself, thereby rendering it obsolete. So while people may lament things like elevated expressways, ravines and viaducts, that’s due more to a lack of imagination and creativity than any objective understanding of the problem at hand.
There are any number of ways to deal with long and narrow border vacuum problems:
Like a chain of 5 year olds playing Red Rover, long and narrow borders tend to collapse in the face of any reasonable amount of force. They’re easy to tackle if you have the political willpower and civic creativity to do so. We need to stop making them out to be the monsters they aren’t.
We need to admit that the problems they pose aren’t that great, solve them and move on.
The real challenge are those thick and wide border vacuums (like waterfronts) that present massive geometric problems to urban designers, planners and citizens alike.
- I’m not big on when Jacobs and Lynch describe functioning borders as “seams” because that implies a clearly demarcated start and finish – which I think detracts from Jacobs accurate understanding of how functional districts and neighborhoods overlap one another. I prefer to think of them as finger or dovetail joints.
- Due to the platitudes typically bestowed upon Millennium Park, I fully expect people from Chicago to jump all over me for saying that turning a waterfront into a park is an inefficient waste in winter climates. My question to Chicagoans is this: How usable is Chicago’s waterfront and Millennium Park in the depths of winter? That’s an honest question not a challenge. And: Were there other ways to design it such that it was usable year round?