Saturday Night Nerd Time: From Sharrows to “The Structure of Scientific Revolutions”

While I generally enjoyed riding, for the first time, a bicycle in Nashville recently, this particular stretch wasn’t too much fun:

nashville sharrow
40 mph and uphill. But it’s a Bike Route! And there are sharrows!

The bike infrastructure “treatment” known as the sharrow has been around since the early 1990s, originating in Denver. I’m personally not a big fan. Actually, I don’t think the sharrow has any big fans. It’s something like the green bean casserole of road signage, nobody’s favorite, but everyone feels like it should be there in certain situations, like Thanksgiving, or when the road is too narrow for real bike infrastructure.

The sharrow is an admission of guilt. The sharrow is us throwing up our hands. The sharrow is that “wish sandwich” Elmore Blues raps about.

All that whining aside, the highly respected National Association of City Transportation Officials (NACTO) states that there are roadway configurations in which Shared Lane Markings are “desirable.” As you might have guessed, the stretch of Nashville’s Rosa L. Parks Boulevard pictured above is not one of these configurations.

Specifically, NACTO points to:

On bicycle boulevards or similar low volume, traffic calmed, shared streets with a designed speed of < 25 mph.


On downhill segments, preferably paired with an uphill bike lane.  If space permits, consider a wide downhill bike lane.

Still, NACTO does state a condition which fits the Nashville situation above:

To fill a gap in an otherwise continuous bike path or bike lane, generally for a short distance.

And yes, this amounts to NACTO making a “wish sandwich.”

Bringing the discussion to Burque, BB has always intended to have a “Worst Sharrow in Town” contest, but hasn’t gotten around to it. I can’t recall a sharrow as harrowing as the one I came across in Nashville, but maybe part of the scariness there was that first time riding in the area thing.

Do we have any uphill, posted 40 mph or higher, no shoulder sharrow treatments in ABQ? I can’t recall anything close, although that’s probably my poor memory at work. Readers are very much encouraged to point out places my memory has successfully repressed.

I bring all this up simply to whine about my Nashville experience, but also to posit that we’re never going to get anywhere near “Vision Zero,” or other significant safety transportation goal as long as sharrows exist. Moreover, as long as sharrows and “Share the Road” sign dot our bicycle infrastructure, we’ll be forever faced with the confusion over what “share” means:

  1. Does it mean share vertically, as in the bicycle takes the lane, or
  2. Does it mean share horizontally, as in the bicycle is allowed to way over there next to the gutter pan?

I know most BB readers know the answer to this question, but, as you also know, THEY don’t know the right answer to this compound question, although THEY think THEY do.

I was lucky in riding up that hill in Nashville, where only one or two motorists zoomed around me going at least 40 mph while I huffed and puffed at 7 mph uphill on my 57-pound bike share bike. Yes, I “took the lane,” but only because these drivers graciously started their zoom around early, and traffic was light enough to easily do so in a non-rush hour situation.

Trust me, if those motorists started later, I was prepared to get as close to that wall as quickly as my 57-pound bike would let me.

nashville sharrow

One other observation about Nashville. Their “Bike Route” signs are just as confusing, slightly dangerous, and overall fairly useless as those in Albuquerque. It’s been the same in every U.S. city I can recall via my porous memory. I think all Burque cyclists have seen at least a few “Bike Route” signs that we certainly hope no visiting tourist has EVER consulted for wayfinding guidance.

We should have a BB contest for “Worst Bike Route Sign,” too, I guess.

Once again, my point in all this whining is actually “solutions-based.” We really can and must solve the problems of sharrows, what “share the road” means (here’s a signage improvement on that front), and wayfinding signage if we are to be able to both make non-motorized travel on our roads safer and build bicycle ridership to that level of “safety in numbers” so very necessary to create anything close to the Vision Zero ideal.

Of course, the problem with “solutions-based” in terms of these issues is that the solutions are so damn hard. Or at least they appear so.

Let’s take one more look at the Nashville situation:

nashville sharrow

To fix this in any meaningful way, Nashville has to either:

  1. Reduce the speed limit here to 20 mph (which really doesn’t address the whole uphill 7 mph thing, although it would certainly help in terms of severity of potential crashes);
  2. Pave that gravel between the right lane and wall and put in a bike lane, buffered/separated or no;
  3. “Diet” Rosa L. Parks Blvd. to one driving lane with a bike lane treatment in the right lane; or,
  4. Something I’m not smart enough to dream up.

And all those, including the one you dream up, are probably “hard,” i.e., expensive and/or politically untenable, at least in the present, non-Vision Zero, paradigm of roadway engineering.

But here’s a funny thing. Not being from the area, I assumed, as I huffed and puffed up this hill in Nashville while checking my helmet mirror about every 4.2 nanoseconds, that the traffic counts on Rosa L. Parks Blvd. in this stretch must be far too high to allow for a road diet. And, being the nerd that I am, I came home and checked the actual traffic counts:

nashville traffic count

Hmm. Interesting, particularly when one looks to the Federal Highway Administration for guidance on maximum traffic counts and road diets:

The FHWA advises that roadways with ADT of 20,000 vpd or less may be good candidates for a Road Diet and should be evaluated for feasibility.

The FHWA publication linked above also has a handy-dandy graphic with how three different U.S. cities view traffic count maximums for road diets:

fhwa road diet

Hmm…25,000 huh?

It must be noted that I’ve actually heard some of the numbers mentioned above by a loyal BB reader who, when he told me the Seattle number, had me nodding my head in semi-comprehension and mostly disbelief.

So why didn’t Nashville road diet this section of Rosa L. Parks Blvd. instead of using sharrows? I don’t know. If anyone, somehow, reading this from Nashville would like to chime in from Music City with any political or traffic count guidance, I’d love to hear from you. Maybe Nashville is much more Pasadena, California than Seattle, Washington.

I can discern from riding quite a bit around Nashville that it has evidently seemed impractical to do something more than sharrows in this stretch. Other parts of town have much better bike infrastructure. As such, Rosa L. Parks Blvd. is probably an excellent example of the need to change the fundamental emphasis of what is considered impractical in roadway engineering. The paradigm must change from:

Motorists get from Point A to Point B as quickly as possible while killing a reasonable number of people


All roadway users get from Point A to Point B as safely as possible.

The solution is more complicated in execution, but it really boils down to this paradigmatic change. Those interested in both the paradigm and the complexity of solutions are encouraged to read the new RAND Corporation study “The Road to Zero,” (full report here).

As good ‘ol Thomas Kuhn told us time and again paradigmatic change is a revolution, and revolutions are hard. They won’t happen just because some blogger in Albuquerque writes 1,500 words about them in a post. Or two. Or three. But seeing RAND now involved with this issue is about the best evidence yet that a revolution may truly be afoot, so to speak.

A scientific/technological/political/social transportation revolution? Now that would be fun to not only watch, but participate in. Much more fun than I had riding up that Nashville hill sharrow lane on my 57-pound bike share bike. Much more.





One thought on “Saturday Night Nerd Time: From Sharrows to “The Structure of Scientific Revolutions”

  1. I agree that the “sharrows” symbol and usage is like a “green bean casserole” (combined with canned kidney beans), but at least it’s directional, so that riders should understand to ride with traffic, unlike the diamond symbol that has also been used on bike lanes, confusing users on which direction to ride. These diamond symbols were approved before bi-directional “cycle tracks” became the rage, (surely the worst bicycle facility idea ever).
    I’m not going to take credit for puzzling Share the Road signs because I designed the first Share the Road/Bike Route sign in 1981 with a graphic image of a bike rider riding with traffic and a car (half a car actually) giving them 3′ clearance. It was featured in Bike Forum magazine summer 1981 and the image was later used by at least two state DOT’s. Many local variations followed as a google image search will show. As far as I know this image coined the term, which spread nationally, and 26 states have since legislated 3′ passing requirements, (oddly enough Michigan required 5′ passing, which makes sharing a lane impossible) although the term may have been floating around before then. I did attempt to have the Federal DOT approve this graphic sign for official use on public roads, instead of their “headless horseman” bike, but the truly Byzantine and costly process was interrupted when the sausage truck hit me.


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