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What Traffic Engineering and Retail Analysis have in common (or My rules are better than your rules)

Rules are made to be broken, but it’s also true they are good to live by.  The good ones can keep us from some of our worst impulses. For example, a good rule of thumb is don’t ever ask someone out on a date by text message. If you care enough to do it, the least you can do is pick up the phone and call. The flip side is that rules can also keep us unnecessarily bound to something artificial and without relevance. We establish rules for ourselves in one context, and then universally apply it to all areas of our life, keeping us locked into a very limited view of the world.

I’m continually confounded by how many rules are imposed on the worlds of urban planning and real estate. Even more interesting is just how sure of those rules some seem to be. Whether it comes from designers, lenders, engineers, appraisers etc. etc., we are confronted with a mind-boggling array of rules to try and make sense of our practice.

The discussion of some of these rules led to a blog-off about retailing and New Urbanism. I’m new to the world of blog-offs, so am jumping into this particular fray about retailing a bit belatedly. But, it’s an important topic, and like all bloggers, I like to throw in my two cents. For links to the other pieces in order, see the list at the end of this piece.

So many rules in the built environment have two fallacies – they are based on sprawl, which is the idea that everything will always be separate from everything else and linked by cars, AND they have a foundation in bad science to boot. The numbers we rely on are based on weak or (in some cases) non-existent research.

Donald Shoup pointed this out brilliantly a few years back with a short pamphlet titled “Roughly Right or Precisely Wrong,” which took to task the so-called science behind many assumptions of traffic engineering. In 6 pages, he directed a devastating attack at some of our cherished rules related to transportation. He’s followed this up of course with many other writings, helping us redefine how we look at transportation planning.

I mention this, because the retail blog-off discussion makes me think of the fallacies of traffic models, trip generation and everything related to traffic engineering. The discussion has resolved largely around the “rule” that 1,000 households are needed to support a corner store. It’s unfair to pick on this particular rule alone – there are dozens that are similar. And, I’m not disparaging all of the rules that Bob Gibbs writes and speaks about – many of these are very useful and indicative of a great deal of study of human nature.

But when it comes to picking numbers and using them for urban planning, I always get more than a little nervous. I know the numbers are averages, but seriously – consider the factors that influence the provision of retail:

  • What’s the income of the people?
  • What are their buying patterns?
  • Where are they coming from?
  • Are they generally sociable?
  • Do they shop much on the Internet?
  • What is the transportation infrastructure?
  • Is the business a chain or family-owned? How is it financed?
  • Are there other draws to the area, civic or commercial?
  • How expensive are the buildings?
  • Are they new or old buildings?

Whenever I get lost in a mental quandary like this, it helps me to try and look at real-world examples. Call me crazy, I like to look at precedent.

In this case, I thought I’d look at Slater, Missouri. I’m sure you’ve never heard of Slater. It’s a small town just to the east of where I went to high school in Marshall, Missouri. Slater is quite literally in the middle of nowhere. In 2000 numbers, it’s a town of 2,083 people nestled along state highway 240. That’s state highway, not US highway. For those of you travelling, that’s the road connecting Marshall and Moberly. Slater’s claim to fame is that for a brief time Steve McQueen lived there as a youth.

To get just a bit more familiar: Slater’s simple grid of streets is about ¾ mile by 1 ¼ mile effectively. The density is less than 1,500 people per square mile, the median age is 40, and the median household income is around $26,000. By comparison, the County median income is north of $38,000 and the state is just over $46,000. The county seat of Marshall is 13 miles away, with a population of 13,000. The entire county population is 23,756. Slater’s household size is 2.26, with just under 900 households in the city.

Slater MO
Slater MO

As you can see, there’s nothing terribly remarkable about Slater, which is exactly why I pick it to make my case. In the town itself, you’ll find a 3 block long main street that ends at the railroad, and blocks that are roughly 450 feet square. Some of the businesses in Slater include:

  • Grocery store
  • General store – mostly hardware
  • Pizzeria
  • Pharmacy
  • Chiropractor
  • Motel
  • 2 Insurance agents
  • Vet
  • Bank
  • Video store
Main Street, Slater
Main Street, Slater

Now, according to the rules of retail, this town of less than 1,000 households, of below-average income cannot even support a corner store.  And yet, while this is certainly not a thriving, picturesque example of Nolen-inspired urbanism, it still supports multiple businesses within a reasonable walking distance. Certainly a few customers come from the surrounding rural areas (although the vast majority gravitate toward the county seat of Marshall), and a few more come from the state highway passing by. But let’s be honest, those numbers are tiny.

At what point do we, as New Urbanists, toss out these rules that constrain us, much like we’ve done with conventional traffic engineering and conventional zoning? I would suggest that this desperate attempt at quantifying urbanism is a fallacy at its core – what we do is much more social science than applied science. Numbers are helpful at times, but they are all-too-often a straightjacket that provides little of real utility, and sometimes are downright misleading. Observing the world and human behavior, though – now that is something much more worthy of our time and study.

This is but one example – we have so much more to learn from. Whether it’s the countless towns across America like Slater, both thriving and not, or the older, historic neighborhoods of our larger cities, we have a bevy of walkable commerce we could be studying.

Instead, we spend our time finessing rules that are not urbanist in nature – they tell us virtually nothing about how people live in truly diverse, walkable neighborhoods. They tell us A LOT about how people live in suburbia, where everything is easily counted like so many beans.

We need a new practice for looking at urbnaism and retail, and it should start by looking at precedent. Let’s go back to the beginning. Remember the early days where we patterned our developments off of actual places? We can learn far more about retail by studying the good, the bad and the ugly of our precedents rather than by reading more literature from ULI.

Blog-Off Participants and Articles:

1. The Original Green, "The Necessity of Hope"

2. Placeshakers, "Retail: When it Bends the Rules and Breaks the Law"

3.  Street Trip, "BlogOff: Neighborhood Retail"

4.  Walkable DFW, "Retail BlogOff"

5. Kaid Benfield, "When shops and services are within walking distance, we walk more and drive less"

6.  Olson Planning, "Neighborhood Retail Dynamics"

7.  Chip Kaufman, "Neighborhood Retail"

8.  Steve Mouzon, "New Urbanism For All?"

The over-supply of single-family housing

The over-supply of single-family housing

Why are we so fat?

Why are we so fat?

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