12 September 2017

[Address Nerd] Where Is A Quadrant Not A Quadrant? West Des Moines, Iowa

This is a bit of brain-bending niftyness I stumbled on while finding the why of the street grid of greater Des Moines, Iowa (an interesting subject in and of itself, and one whose origins are ever more obscure than those of our beloved PDX).

There is a large town subordinate to Des Moines called (not surprisingly) West Des Moines. Now, Des Moines and most of its suburbs are located in Polk County, Iowa, which has an address grid and street naming/numbering and directional rationale based on the center of the metropolitan city, like here in Portland; specifically, the point where Vine Street crosses the Des Moines River. Addresses radiate out in all directions from that point as do street directionals (mostly).

West Des Moines, when the greater DM area was ordered, decided to take a pass. It has its own grid. Starting with 1st Street on the east edge of the city (which happens to be the city limits and abuts the city of Des Moines, sharing DM's 63rd St/SW 63rd St) numbered streets progress to the west. A line approximating Railroad Street and E.P. True Parkway (and certain streets west of where E.P True begins to meander) spits the city into north and south halves and is the baseline for north-south addressing; addresses on east-west named streets run 100 to the block and are synch'd with the numbered streets, same as you may be familiar with here.

The basic plan resembles this:

The only directional prefix in the basic plan is South, and that only applies to numbered streets that extend south of the Railroad Street baseline (35th Street north of Railroad becomes S. 35th Street where it's found south of Railroad).

Now, direct your attention to that meadering blue line separating the upper 2/3rds of the city from the lower 1/3rd (more or less). That's the Raccoon River, and for a number of years, WDM pretty much ended there. But cities grow, as they do, and eventually WDM started annexing land south of the Raccoon. There are only two ways from the main part of WDM into this section: A bridge on S 1st Street, and the bridge that carries Interstate-35 into the area. This makes that area comparatively remote and relatively inaccessable to the rest of WDM, and did emergency responders in the area a concern, as detailed by the city council proceedings that are linked to in the article I stumbled on in a blog called Iowa Highway Ends:
Lynne Twedt, Addressing Administrator, reported on the background of this proposal to add locational prefixes for roadways south of the Raccoon River. She stated as the City develops south of the Raccoon River, it will pose a greater challenge to public safety personnel responding to those areas, because there are currently two river crossings in the City. It is critical that the public safety responders know immediately based on the street name whether or not they need to go south of the river.
So ... addressing administrator? Has that got to be the best job ever or what?

Anyway, that was their concern. Whether or not it was too much of a concern is a exercise I leave to the reader, but that was their feeling. Here is how they solved it:

  • All the streets in the area east of I-35 and south of the Raccoon River get the prefix SE
  • All the streets in the area west of I-35 and south of the Raccoon River get the prefix SW
The observant reader will note that the area deemed SW is actually terribly tiny, and is dwarfed by the SE area, but the logic is consistent in and of itself. Here's the map with the 'demi-quadrants' added:

But here's the crucial point here, and one which may leave some conventionally minded address nerds scratching our heads: only the street names have any respect to these boundaries. That is to say, the street names have been modified, but the addresses have not. As soon as South 1st Street crosses the Raccoon River, the street name changes to SE 1st Street, but the addresses continue to progress as they were. The address grid remains as before, relative to the origin point of Railroad Street and 1st Street. The demi-quadrants are really just region names, cluing in the first responder (or address seeker) that if you have an address beginning in SW or SE, you merely know to look south of the Raccoon River to find it. This is an innovative, if awkward-to-the-layman way of at least letting you know where not to look for your address, and if sufficiently familiar with the streets, making the most efficient guess at which of the limited number of accesses is your most efficient route.

And if anyone in the City 'o' Portland comes up with the idea of an Address Administrator (or, anyone in any Oregon city), well, I'm available. 

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