Malcolm Gladwell on Jane Jacobs, the 85th Percentile Rule and Local Manufacturing

The solomon curve

Here are a few interesting articles I’ve read lately.

The Tissue of Straight Lines: a meditation on NYC’s grid street network from Kneeling Bus, one of the few blogs I read which leaves me saying, “I wish this guy wrote more articles.”

The grid that originated in 1811 will never be finished as long as it remains in place, because it will never stop challenging its inhabitants to infuse its neutral, rectangular blocks with the vibrant content of humanity and culture.

Designs For Working: Malcolm Gladwell on Jane Jacobs, author of the seminal The Death and Life of Great American Cities, and how her ideas have been co-opted by corporations looking for collaborative, social working environments. See: Zappos’ plan for Las Vegas.

Sparely populated suburbs may look appealing, she said, but without an active sidewalk life, without the frequent, serendipitous interactions of many different people, “there is no public acquaintanceship, no foundation of public trust, no cross-connections with the necessary people–and no practice or ease in applying the most ordinary techniques of city public life at lowly levels.”

This has been going around like wild fire. The 85th Percentile Rule in Traffic Engineering from Copenhagenize: an outdated way of setting traffic speeds which ignores neighborhood context, pedestrians and cyclists. This model is still being used in many U.S. cities.

Solomon Curve graph
“The Solomon Curve, developed in 1964, states that those driving slowest will be at the greatest risk of crashing. This outdated model, which ignores pedestrian safety entirely, still guides traffic engineering toward higher speeds.” StreetsBlog

Imagine a street where the average speed is 50 km/h. If the speed limit is reduced by 5 km/h then, according to this archaic model, the drivers are allegedly exposed to a higher risk. What is most shocking is that this entire concept completely ignores pedestrians and cyclists. Another horrific conclusion from this graph is that when you increase the speed limit, the crash risk is alleged to be less than for slow speeds.

The Institute of Traffic Engineers wrote: “The 85th Percentile is how drivers vote with their feet”. They forgot to mention that, when it comes to establishing speed limits in cities, pedestrians and cyclists are excluded from this election. They don’t even get the chance to go to the polls.

And finally, the benefits of preserving local manufacturing districts. Proximity is Creativity: Unlocking the Value of the Garment District from Urban Omnibus. There are some things China just can’t do.

Let’s say it’s your last year at school, and you have a set of starter designs that are very marketable. What happens next? You need to get someone to make your production patterns; you need to able to source fabrics; you need to be able to sell, to have access to the stores. So let’s say you come up with a 20-piece order. You can go out into the Garment District, find a cutting room or a sewing room, and have your 20 pieces produced and shipped to a store. You can’t get only 20 pieces made in China, not today, not ever. That is what validates what goes on in the District today: the capacity to produce short runs, samples made with a quick turnaround time.


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