Low Speed Street Design: Don’t Let It Fall Through the Cracks


By Dom Nozzi

September 8, 2002

In general, communities need to provide for the full range of lifestyle choices. Who am I to say that EVERYONE must live in walkable urbanism I personally prefer? If some want to live in what I consider to be sterile, auto-oriented suburbia, they should have that choice. As long as I don’t have to pay more in taxes or worsened quality of life — i.e., their costs admin-ajax (10)are internalized. And as long as they don’t insist that their suburban designs be incorporated in walkable town centers.

Low-speed design is quite appropriate for a town center, but increasingly inappropriate as one moves further and further from the center. Way too much distance between origins and destinations to make such speeds tolerable or appropriate.

One size does not fit all, in other words.

In a presentation I saw about 18 months ago, a design expert pointed out the concept of “low-speed street design” — a very interesting concept that I did not know about beforehand. One must wonder if conventional traffic engineers prefer that low-speed street design be somewhat of a secret in order to maintain the century-long obsession with the design imperative of free-flowing, higher speed car traffic.

In other words, perpetuate the illusion that low-speed design is not an option on the table. Ever.

The crucial point of the street design expert was that one of the traffic engineering bibles (probably AASHTO Green Book) contains design specs for “low-speed urban streets,” or a term like that. Such specs are for the creation of streets designed for 15-20 mph street speeds, which therefore specify tight turn radii, tiny clear zones, tiny vision triangles, etc.

I was stunned to learn this.

In other words, the standards I had always been dreaming about EXIST in the national manual. I (and others) just didn’t know that they were there to ask for (so the engineers never use them). Ever since then, I always make it a point to ask if it is possible to use those “low-speed urban street” specs when a street is being designed. Unfortunately, I am not enough of a traffic engineer to be able to know the details about these specs, or how to find them in the manual.

Keep the term “low-speed street design” in mind the next time you are involved in designing streets in a town center. Be sure that the engineers intend to use such design, rather than “forgetting” and opting instead for inappropriate, one-size-fits-all suburban design.




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