Tuesday, May 14, 2013

Kuebler and I-5: Epicycles and Sidewalkification

Things are heating up in discussions for the design of the Kuebler Road and I-5 interchange, and a proposal has been making some rounds in neighborhood meetings.  The proposal is for something shiny and new, but at best (and this is at present more theoretical than established, as even the project team says many of its benefits are yet "theoretical") it offers tiny, incremental change for people on foot and on bike.

I don't know how much time is worth spending on this. The project is already well underway, and it's in a part of town that is already so screwed up it is nearly irredeemable.

Even the best project will only begin to address facilities for a few more than those exclusively among the "strong and fearless" people on bike - it would barely make inroads to address the needs of "enthused and confident" and doesn't get anywhere close to addressing the vast majority of those "interested and concerned."  When you look at it, you will wonder how many moms would send their child on it.

So this falls under the rubric of "pick your battles" and I don't think this is a battle to choose.  It's between bad and bad - and how much does a slight difference in bad really matter?

Anyway, if you're curious...first came to notice back in January, when Curt pointed it out in a comment.  A developer was using a new ODOT process to propose a different interchange design for a project authorized in the Legislature's big 2009 roads package.

Diverging Diamond
The proposed design is a diverging diamond and the project team is taking it out to neighborhood associations, last month to Morningside neighborhood.

The design can be seen in Springfield, Missouri, at the intersection of I-44 and MO-13.

The spaghetti makes you think of Ptolemaic epicycles, additional whing-doodads necessary to explain retrograde motion and other non-circular movements in celestial objects in a system centered on the earth.  (Whew!)  As the measurements got better, increasingly complicated schemes were necessary to explain the observed behavior of the planets.  Finally the number of epicycles became so numerous they crashed the system and finally Kepler came along and proposed elliptical orbits around the sun, which offered a much simpler model and better accuracy to boot.

So - the lengths to which engineers want to go to improve traffic flow and more-than-a-little spuriously to "improve" the experience of walking and biking looks here like adding epicycles and unnecessary complexity to a model of mobility that is already coming apart and should be on its way out.  All this road spaghetti can't be that good!

What we need is a new paradigm - not more epicycles.

How complicated is it?  For people on bike, the diverging diamond requires lots of sidewalkification:
  1. a move from bike path up onto the sidewalk
  2. a 90 degree turn into a crosswalk
  3. a move through a pedestrian channel
  4. another crosswalk
  5. a long channel down a central median on the overpass
  6. back over a crosswalk
  7. another move through a pedestrian island
  8. a crosswalk and 90 degree turn
  9. onto a sidewalk
  10. and finally back into a bike lane
Here's a mash-up by Charles Marohn of Strong Towns offering a commentary on a narrative and video by an an engineer praising the diverging diamond as pedestrian friendly.

So I don't know. Biking down a center median with concrete barriers with cars speeding by? Yeah, it's probably safer than biking on the shoulder. But getting rear-ended is not that common, so the actuarial increase in safety may not be that much. Biking in the channel is likely to be stinkier than biking on the shoulder, and the aesthetics of the concrete pretty much sucks. The marked crossings may be helpful, but if they aren't signalized I'm not sure that's a big gain either - cars are gonna by zooming by to get on the interstate. And the sidewalkification is annoying! So it's just not possible to see this as a big gain.

Instead, it's all about pumping out more cars, and fitting in people on foot and on bike as afterthoughts in the left-over edges and spandrels.

The greenwash:  It's not bike-friendly
And it's important to remember that this is the kind of "bike-friendly" facility that a new giant bridge and highway promises to bring to the land of milk and honey!

At the same time, it's not like there's some superior alternative floating out there (does anyone know otherwise?), so it's probably not something to spend too much time on.


Anonymous said...

How nice of the neighborhood presentation to plagarize the wiki page for the advantages and disadvantages. Why didn't they just PDF the whole page?

Salem Breakfast on Bikes said...

I saw that, but wondered if both were drawing on a prior document, some list that maybe the Missouri DOT had drawn up. But yeah, maybe the engineering consultant did just lift it off of wikipedia! Neither the engineering presentation nor the wiki piece is especially well footnoted.

Salem Breakfast on Bikes said...

A couple weeks ago City Observatory published a piece with more criticism of the diverging diamond configuration and cites a 2015 research piece.