Sometimes Faster is Better

In past episodes, I've talked about how accidents are the number one killer of children, and how car accidents represent a fairly large part of accidents in general. In response, a number of you asked me why we don't reduce the speed limits of many roads nationwide in an attempt to bring that number down. I'm glad you asked. That's the topic of this week's Healthcare triage.

John Green -- Executive Producer
Stan Muller -- Director, Producer
Aaron Carroll -- Writer
Mark Olsen -- Graphics

[healthcaretriage]

Everyone, this is about highways, not cities or residential roads...

[healthcaretriage]

As promised, I addressed a lot of your questions in a blog post this morning. Go here to read it:
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.

[jjdrummer]

I absolutely love how this show actually has references.

[IznbranahlGoose]

I've known a few, especially older drivers, who have gotten into a kind of feedback loop thinking that 'slower equals safer' so they start driving at 60 in 65MPH zones and you have all these cars swerving and weaving around them and zooming by so they think the entire highway is unsafe so they go EVEN SLOWER.. 50 in 65MPH zones.. and even more swerving and weaving and cars blowing by even faster happened.

It eventually got to the point where they simply afraid to go on interstates at all because they were 'much too dangerous' which is probably a good thing because they were the ones MAKING them dangerous.

[dominikbessler]

I'm from Germany where we have areas on the autobahn where you can drive as fast as you want. But the fatalities per capita is only halve of the US.
There are some factors to that besides the Speed limit.
Anyone has to go to a real teacher to learn to drive.
Trucks can only go about 50 mph.
You can and will get a ticket for staying in the left lane if the other lane is free.
Most people stick to the rule to not pass on right.

[healthcaretriage]

Lots of great questions here. Worthy of a follow-up answer post on my blog. Will post a link in the morning!

[PureDelofan]

I love being told I'm wrong so many times in so many awesome ways on this channel!

[woobmonkeyp]

Out of curiosity, has there been any review of this evidence, with adjustments based on improved safety features in more modern vehicles?

That seems to be an important point that's being missed in this video.

[--sql]

lower speed limit = more time on the road

[nowisgoodme]

As someone who studies civil engineering I'd like to tell what my professor told me. If you are going higher than about 25 km/h, your brain can't comprehend the same amount of information for the same lenght of road, so you start missing things (signs, animals, etc.) which is why on faster roads you get more signs and bigger ones. He told us, that anything moving above that speed has more or less the same chance of hitting a person or thing, the only difference is that roads made for higher speeds are usually more secluded and spaceous which is why less accidents occur. (just an oversimplification)

[divicool]

In New South Wales, Australia, the speed limit for learners is 80km/hr, while for everyone else it's 110km/hr...and driving on highways I feel like this is really dangerous??
Even for provisional drivers, the speed limit is either 90 or 100 :/ And I think THIS IS STUPID.

[Blessedresiliency]

Even if points aren't addressed or missed, I'd say the amount of discussion that springs up around things with these videos is pretty cool. 

[OurayTheOwl]

What about stricter safety laws with seat belts, and improved safety features in cars contributing to the lower rates of fatality and injury? The benefit of being properly strapped into a safer car can be underestimated.

Also what about better designed infrastructure like RT 3? I live in an area where older roads have accidents more frequently, even though they have the same speed limit as the state thruways.

[Swiheezy]

I'm glad you made this, it's a great topic. I'm even more excited for next weeks episode.

[TheOnlyZiTRO]

I totally agree. Everyday on the interstate, the person causing the biggest issue is the the person doing 5 under the speed limit, most of the time on their phone. You have a bunch of steel boxes moving at a certain speed trying to dodge one crawling along & its always going to be bad.

[ButzPunk]

Where I'm from, most driving isn't done on big highways; it's done on residential and urban roads. Could you do a video on speed limits there? It seems like there's gonna be a pretty big difference, considering there's more likely to be distractions and instances where you'll need to stop suddenly, unlike on a rural highway.

[jacks.]

Ah, well ... we have no speed limit in Germany. :)

We have regulated speed limits for certain areas though, for example, in towns it's almost always 50 km/h or lower.

[brandonfrancey]

The amount of controversial comments on this video makes me question how many people actually have their drivers license, let alone regularly drive on freeways. Anyone that spends any amount of regular time on the 401 here in Ontario knows that next to no one drives at the posted limit of 100 kph. (62 mph) With out exaggeration the average speed is about 120 kph (75mph) I'm not talking about the occasional jackass that needs to go faster, I'm talking about the average flow of traffic. The only people you will pass doing 120 is transport trucks and the occasional person doing only 100 because, it's the law. There are still people that go faster. It's not uncommon for people to drive 130 kph (81 mph) or even 140 kph (87 mph) People go that fast because it is a safe highway built and designed to handle these speeds.

The problems that this video addresses is the speed difference between the different drivers on the roads. Speed limits artificially increase that difference on some roads which causes more accidents. Raise the limits to what the people are actually doing and the slow people can catch up with the rest of the people because fear of breaking the law is the only thing holding them back. 

[DoRayMeFa]

It was good that you considered not only traffic fatalities, but also (in one statistic, at least) traffic *injuries*. It may be important to recognize that accident survivability has probably improved over time, due to better designed crumple zones, air bags, etc. A further suggestion is to consider the number of *accidents*--which is the most inclusive statistic. Linking traffic accident rates to lane-changing is an enlightening observation. Thanks.

[happycline]

just a suggestion/question.
is it possible when you list a lot of numbers/dates (like when you were listing the accident rates in the first half of the video) that you put in in a graphic, for non-auditory learners like myself it can be hard to follow just by listening.

I know you (and other people) work hard on these episodes, so I can understand if I'm asking to much, but I thought I'd give my input, since if I don't say anything, how will you know what your viewer(s) want?