In Praise of the Gyratory Circus

There’s a fairly remarkable article in the July/August issue of the Atlantic Monthly, called “Distracting Miss Daisy,” in which the author, John Staddon, argues that “the American system of traffic control, with its many signs and stops, and with its specific rules tailored to every bend in the road, has had the unintended consequence of causing more accidents than it prevents.”

Here’s his take on top signs:

Stop signs are costly to drivers and bad for the environment: stop/start driving uses more gas, and vehicles pollute most when starting up from rest. More to the point, however, the overabundance of stop signs teaches drivers to be less observant of cross traffic and to exercise less judgment when driving—instead, they look for signs and drive according to what the signs tell them to do.

The larger point is that “By training drivers to drive according to the signs rather than their judgment in great conditions, the American system also subtly encourages them to rely on the signs rather than judgment in poor conditions, when merely following the signs would be dangerous.”

Staddon’s proposal is to adopt something like the British traffic system, including the roundabout: “when traditional intersections in the U.S. have been replaced by roundabouts, collisions have typically been reduced by about 40 percent, and fatalities by up to 90 percent.”

If you drive in the U.S. (or Canada), I highly recommend reading the entire article (it isn’t long), though afterward you may behave like I did, like a traffic libertarian.

I also recently read a short paper by Joel Fajans and Melanie Curry, both bike commuters from Berkeley, Calif., titled “Why Bicyclists Hate Stop Signs” (FYI, it’s a PDF. The image above is from the article.) Fajans is a physicist, and tackles the problem by looking at how many watts of propulsion an average cyclist generates.

For example, on a street with a stop sign every 300 feet, calculations predict that the average speed of a 150-pound rider putting out 100 watts of power will diminish by about forty percent. If the bicyclist wants to maintain her average speed of 12.5 mph while still coming to a complete stop at each sign, she has to increase her output power to almost 500 watts. This is well beyond the ability of all but the most fit cyclists.

Then the authors put the estimates to the test on a bike route in their home town, which happens to run parallel to a busier route which has fewer stops. In two tests, he was 30 to 39 percent faster.

Because the extra effort required on California is so frustrating, both physically and psychologically, many cyclists prefer [the busier route to the bike route], despite safety concerns. They ride … the official bike route only when traffic on Sacramento gets too scary.

The authors note that “a cyclist who rolls through a stop at 5 mph needs 25 percent less energy to get back to 10 mph than does a cyclist who comes to a complete stop.”

Clearly, stop signs are tricky for bicyclists. On one hand, they increase safety by decreasing the number of cars on a road, and slowing the remaining ones. On the other hand, they make cyclists work much harder to maintain a reasonable speed. For a commuter choosing between a car and a bicycle, the extra exertion can be a serious deterrent.

If you’re not a bike commuter, you may not think this is a big deal. But it is. Many commuters can’t shower at work, so they don’t want to break a sweat. Luckier ones like me can shower, but on weeks when we commute all week, we get run down from the effort (which include going over speed bumps, a great example of a traffic calming device that we face — only without shock absorbers).

I’m thinking the roundabout is the solution for this, too. Motorists would be forced to look for obstacles in the road; cyclists wouldn’t have to come to a complete stop unless traffic was heavy. Plus, roundabouts would help increase traffic flow, instead of the irritating stop-start experience of driving in a residential neighborhood.

BTW, the title of this blog post comes from an anecdote in Bill Bryson’s excellent book, The Mother Tongue: English and How It Got that Way. He relates an anecdote that the word roundabout was actually coined by an American living in England, who was working on some BBC commission on English. Before the American’s improvement, a roundabout was known as a “gyratory circus”!