Before your blood pressure start to go off the chart dear colleague, have a careful look at what Dr. Aaron Carroll, also known as the Incidental Economist, has to say on what may appear to be a counterintuitive approach to our favorite topic (or at least one of them) speed and safety.
Thanks for the reminder Aaron that in our complex field, things are not always what they may at first glance appear to be. One thing for sure: a street is not a road (but then you knew that when you were preparing this little mind trap and wake-up call).
Sometimes Faster is Better
- Aaron Carroll. Indiana University School of Medicine
In the past episodes I have talked about how accidents are the number one killer of children, and so car accidents represent a fairly large part of accidents in general. In response, the number of you asked me why we do not reduce the speed limits of many roads nationwide in an attempt to bring that number down. I am glad you asked. That is the topic of this week’s Healthcare Triage.
Those of you who want to read more and see references can go http://theincidentaleconomist.com/wordpress/healthcare-triage-sometimes-not-always-faster-is-better-ctd/
More from the author on speed and what he is actually saying:
Here is the text:The video brought out a lot of great questions in the comments. Enough that I think it’s worth a follow-up post to address some of them. I’m paraphrasing them. Here we go:1. There are studies showing that people who drive slower are less likely to die than people who drive faster. Doesn’t that bother you?
Well, sure. But a lot of those studies are showing that people who drive less than 30 mph are less likely to die than people going 40 mph. I’m sure people going less than 10 mph are going to die even more rarely. If we don’t drive at all, it will go down even further. I’m not disputing this fact. We accept a certain amount of risk when we drive.
But this video wasn’t about speed – it was about speed limits. The question is whether a 55 mph speed limit is always safer than a 60 or 65 mph speed limit. That’s not as clear.
2. How can you advocate for higher speed limits (of even 65 mph ) in a city?
I don’t!!! We’re talking about highways here. I said that I don’t think we should do away with regulation. Residential areas, school zones, those are a whole other story.
3. Aren’t you cherry picking by citing Lave? Doesn’t other research show that lower speed limits reduce fatalities?
I tried not to cherry pick. But you’re misinterpreting me. I take the fact that the literature is equivocal on this to mean that there are probably times when slower speed limits are better and times when faster speed limits are better. I’m not advocating for higher speed limits across the board. The point of the video was to push you to question your bias that slower is always better. Sometimes (not always), faster speed limits may be better.
4. Aren’t you advocating that people break the law here?
Nope. I’m advocating that we should sometimes change the law because people not following it is leading to a bad outcome.
4a. Isn’t that really saying that people shouldn’t be held accountable for breaking the law?
Nope. I think people should follow the law. But sometimes, in the real world, they don’t.
4b. Shouldn’t we just punish them?
This is a critical point, and worth of debate. I view this as the difference between efficacy and effectiveness. In an ideal world, everyone would do what we tell them perfectly, and we’d get the “efficacy” of speed limits. In the real world, lots of people don’t, and you see the “effectiveness” of speed limits. The effectiveness is often much less than the efficacy. If we can’t change the world to make efficacy work, we should deal with effectiveness. Sometimes, that means raising a speed limit. We’re not doing it to benefit lawbreakers. We’re doing it potentially to prevent accidents and save lives.
5. Shouldn’t we listen to engineers who tell us what the speed on a road should be?
YES! That’s exactly what I said in the Route 3 example, where engineers rated the road much higher than 55 mph. Looking back at effectiveness, it turns out that people may be, in general, pretty decent at figuring out intuitively what a safe speed on a road would be. If you set the speed limit near that number, more people drive the same speed. If you set the speed limit too far below that, you get a lot of people driving at different speeds. I’m advocating for listening to the engineers.
6. What about pedestrians?
Pedestrians shouldn’t be on highways!
7. What about animals?
I have no data on that. But I have to say that almost all highway laws are about protecting humans, not animals.
8. Why do you focus on the US?
I use the US as an example. I live there, and I know its policies best.
9. Traffic cameras could fix all this!
Maybe. But they’re not in use like that in the US, and if they were, maybe the evidence here would be different. They are, in their own way, an attempt to improve efficacy, by making more people follow the law. That’s another option, but perhaps expensive. And not everyone will tolerate monitoring.
10. Don’t improvements in cars reduce fatalities and accidents? How do you know it’s not that, but instead speed limits?
We don’t. I think they’re absolutely reducing fatalities. Accidents, to a lesser extent. But these are responsible for both better outcomes with lower and higher speed limits, and people on both sides use them to bolster their claims.
Let me finish by repeating what I said in the video. Sometimes we have to question our biases for the real world. There are times when lower speed limits are better. But there may be times when higher speed limits are better. NOT ALWAYS. But sometimes.
* Reprinted with permission of and thanks to the author. Original YouTube video at https://www.youtube.com/watch?v=wzVaa557I9k&feature=youtu.be
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Bio: Trained as a development economist, Eric Britton is MD of EcoPlan International, an independent advisory network providing strategic counsel for government and business on policy and decision issues involving complex systems, social-technical change and sustainable development. His forthcoming book, “Toward a General Theory of Transport in Cities”, is being presented, discussed and critiqued in a series of international conferences, master classes, workshops and media events over 2014. (More at http://wp.me/PsKUY-2p7)