Is Every Speed Limit Too Low?
This article ignores a lot of peer-reviewed literature from planning, public health / injury prevention, and civil engineering in favor of some folksy wisdom of a lieutenant cop. A good starting mental model is that vehicle speeds increase both the frequency and severity of crashes.<p>The article weakly, and quietly made an argument that I <i>do</i> agree with. Namely, roadway design needs to accompany speed limits to ensure people actually drive the desired speeds. Wide lanes, big setbacks, homogenous environments encourage speeding regardless of what is posted. But let's be clear, we should have our design follow our policy, not our policy follow bad designs that were put in place by roadway engineers of yesteryear.<p>That message seemed to be lost in the race to tell us something tantalizingly counterintuitive. I love "everything we know is wrong" storytelling as much as the next guy, but only when that's actually backed up with solid evidence. Take for example this gem from the article:<p>> “We all speed, yet months and months usually pass between us seeing a crash,” Lt. Megge tells us when we call to discuss speed limits. “That tells me that most of us are adequate, safe, reasonable drivers. Speeding and traffic safety have a small correlation.”<p>That would seem to be at odds with this peer reviewed article (sorry, paywall, but you can read the abstract):<p>> Respectively, they found evidence for an exponential function and a power function between speed and crash rate. Both types of studies found evidence that crash rate increases faster with an increase in speed on minor roads than on major roads. At a more detailed level, lane width, junction density, and traffic flow were found to interact with the speed–crash rate relation.<p>Link to article: <a href="http://www.sciencedirect.com/science/article/pii/S0001457505001247" rel="nofollow">http://www.sciencedirect.com/science/article/pii/S0001457505...</a><p>Priceonomics's banner ad tells me it is selling a new book titled "Everything is Bullshit." Quite right.