Speed limit: 11 Miles Per Hour

I was recently at a Hyatt hotel in Lost Pines, Texas. The posted speed limit on one stretch of road was 11 mph. In another area, it was 19 mph. Very clever. My guess is that if you did a randomized experiment, actual driving speeds would be lower with the 11 mph speed limit than the more familiar 10 mph limit.

The first time I saw a speed limit like this was in grade school, where one of the teachers had a mock traffic sign that read “Speed Limit 3 mph.” She was an art teacher. I can remember nothing about her or her class other than this — I’m not sure what grade it was, or even what school. Whenever I run into my own former students, I ask them what they remember from my class. Invariably it’s something equivalent to this traffic sign that they remember, like a story I told about my wife that had nothing to do with the subject matter of the class. Which is why, when I teach, I try to tell a lot of stories about my wife.


egretman

Is Levitt being courted as Ron Paul's future White House economics adviser?

Lost Pines is just a hop, skip, and throw from Ron Paul's Texas 14th district, the fightin' rice farmer's district of South Texas.

Very clever to meet in a nearby neutral location in order to keep it all hush-hush. Well done, Mr. Levitt, well done.

ithaca99

Shwa. 4th grade. Phonetic symbol for the sound that insane English orthography represents with any vowel that happens to come along (th[e], [a], opp[o]sit[io]n, vill[a]ge, horr[i]b[]le &c &c &c). I was appalled. I'm still appalled. Think of the money poured into 'No Child Left Behind'. Think how much less money it would take to add a single letter, shwa, to the English alphabet, and let people use it spell our favorite vowel. I remember hearing our teacher explain that there was a symbol for this sound which we NEVER USE, and thinking it was outrageous that children were being taught a senseless system.

prosa

The Texas sign makes perfect sense. Hardly anyone will notice a sign that says 10 mph. But just about everyone will notice a sign that says 11 mph.

coyotesqrl

Maybe the speed limits are just to honor local heroes, like at Ole Miss.

jonathank

BUT: do people drive closer to the speed limit? And are conditions on the road such that people have to drive slowly anyway so the sign stick out more? In other words, is there more efficacy or is this like ads where people remember the name but don't buy more of the product?

greenbirds

I've seen a couple like that here as well (Greenville, SC). The next door apartment complex has an 11 mph speed limit and my work campus has a 24 mph speed limit. I think it does make a difference.

greenbirds

What makes a bigger difference is what I've seen in some parts of San Diego, esp. around school zones. They have a speed limit sign with a radar set-up to display your current speed on a sign that reads "your speed is..."

People slow down on those all the time, even though it doesn't record their speed, it just displays it publicly.

greenbirds

...something similar to http://www.rbwm.gov.uk/graphics/lge_transport_SID_500x375.jpg

pparkman

There's a street near me where each curve has a different speed limit. And it's been like that since I could drive 30+ years ago. Anyone interested in testing Dr. Levitt's hypothesis could find the traffic data on Quito Road in Saratoga, CA, and compare it to a similarly windy road with a similar traffic load. Dr. Levitt, the ball is in your court!

frankenduf

or there'll be more accidents from people doing double takes of the odd limits?!

diogenes

I thought some neighbors of mine were very clever: They have "Slow down for kids" signs up along their residential, but straight and heavily traveled street, but then they change them every two months or so. There are kid-shaped signs, blue signs, yellow signs. Someone probably keeps the spares in their garage and changes them out on a nice Saturday. I think it is very effective at keeping people's attention over time.

goinglikesixty

Speed limit? What's that?

kdmick

I haven't seen any data on this, but common sense (which is often wrong, unfortunately) leads me to believe people frequently speed out of absent-mindedness/lack of attention than the desire to go faster (at least this seems so after the age of 22 or so). Any posted sign that merits more attention would have this effect.

Juggling Frogs

This is why my father gave me a bedtime of 9:07 p.m. when I was a child.

Kent

I would think that conventional speed limits (55 mph, etc.) are intended to have focal points that reduce the search cost of learning what the speed limit is. At 55 mph on a highway in many areas you can just almost assume it. Perhaps there's a benefit attached with a single stretch or road having an unconventional limit to draw more attention to the preferred speed. But if all roads did this it would be bad in aggregate.

armchairpunter

It seems to me that the easy (though not necessarily correct) answer would be that we tend to treat 0's and 5's as indicative of a rounded number and rounded numbers are rarely treated with any precision. Most of us tool down the highway at a speed within a consciously or unconsciously established buffer keyed to the perceived likelihood of enforcement or the breakpoint at which penalties of a certain degree of harshness (a stiff fine vs. losing one's license vs. jail) might kick in. We establish that buffer based upon multiples of 5 or 10. Those attempting to set effective speed limits in a given special locale want to suggest that the margin of tolerance is much tighter. A speed limit of 10, 15 or 20 could be more likely to tap into the same first-digit disregard we employ in our highway buffering. Choosing a less commonly employed figure for that digit has a better chance of slipping through our buffering system, or at least causing us to tighten our buffering to something less than a multiple of 5 or 10.

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FRANK

Well, we will see if we see more unmark cop cars to control how fast People are driving. i.e. Cops may not want to give 5 over, and so, a Ticket will be issue, therefore, just because other people are driving in a danger manner. does not mean that you will not be caught.

1-3 not worth it. 4-5 Warning. 6-10 Ticket. 11-20 Double 21+ Triple.
$58 $105 $220 $440

Sooner of later. enough Speeding Ticket giving out means that the Cops Salary will be paid for.

egretman

Is Levitt being courted as Ron Paul's future White House economics adviser?

Lost Pines is just a hop, skip, and throw from Ron Paul's Texas 14th district, the fightin' rice farmer's district of South Texas.

Very clever to meet in a nearby neutral location in order to keep it all hush-hush. Well done, Mr. Levitt, well done.

ithaca99

Shwa. 4th grade. Phonetic symbol for the sound that insane English orthography represents with any vowel that happens to come along (th[e], [a], opp[o]sit[io]n, vill[a]ge, horr[i]b[]le &c &c &c). I was appalled. I'm still appalled. Think of the money poured into 'No Child Left Behind'. Think how much less money it would take to add a single letter, shwa, to the English alphabet, and let people use it spell our favorite vowel. I remember hearing our teacher explain that there was a symbol for this sound which we NEVER USE, and thinking it was outrageous that children were being taught a senseless system.

prosa

The Texas sign makes perfect sense. Hardly anyone will notice a sign that says 10 mph. But just about everyone will notice a sign that says 11 mph.