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A Chain Of Causation

Design decisions – in any form of design – affect use. In many cases, decisions affect use in unexpected ways that can be hard to connect to the original decision. The picture above shows an effect that is two generations removed from its original cause, which I find interesting. When I was in high school, I watched a show called “Connections” that followed chains of invention, discovery, and design through science and technology. Having later studied history and specifically the history of technology, one thing about that show that jumps out at me now is that you can chose multiple paths through the connections: they’re never chains so much as deeply-tangled webs.

The picture above shows two apartment houses across the street. The one on the left is a “pre-war” (AKA 1920s or 30s) steel-frame building; the one on the right is an older (probably 1890s or so) bearing-wall building with some nice brick detailing. The space between them is a service entrance for the building on the right. There’s no building behind that tiny wall, just an areaway leading to a rear door. This kind of thing is common with old Manhattan apartment houses. Sometimes there’s a wall, like here, sometimes there’s a vaguely-medieval wrought-iron fence. So, in my initiation of Connections, let’s start in 1811.

The Commissioners’ Plan created the numbered street grid of Manhattan. Parts have changed since then – the biggest change was the addition of Central Park – but the basics are the same as 210 years ago. Wide and widely-spaced avenues run up and down the length of the island and narrow and closely-spaced streets run side to side. The picture above gives a sense of the scale of a numbered street: the typical street is only 50 feet wide and the blocks between streets are 200 feet wide. There are occasional wider streets, spaced at about half a mile apart (14th, 23rd, 34th, 42nd, and so on). The avenues, on the other hand, are mostly 100 feet wide and spaced from 400 to 600 feet apart. (Lexington and Madison are narrower and the blocks on either side of them are closer-spaced because these two avenues were added after the original layout had already started to be built.)

The decision to have such closely-spaced and narrow streets has had enormous implications for the city, starting with traffic jams that are incurable if people use private vehicles. A city with this grid can only move people quickly using mass transit. More importantly for the topic at hand, there are no back alleys. This shows up in all sorts of interesting ways, such as the fact that most buildings in Manhattan, regardless of cost and social standing, have piles of garbage sitting in front on collection days. Service entrances also have to open directly off the street, unless you design your building with a pseudo-alley.

If you’re designing a building of some pretension and you’re creating a pseudo-alley in an areaway, you probably want to hide it. It’s visible next to a street facade that you went to a lot of trouble to design, and it’s going to be full of garbage, coal bins (back when these buildings were built), deliveries, and other reminders of messy and visually unpleasant reality. Or you can hop in your time machine, go back to 1807, and convince the commissioners to make the blocks 250 feet wide with narrow alleys in their centers.

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