Speed, Safety, and Network Effects

Was cleaning out my desk/workspace stuff when I came across a variant of this post in the UC Berkeley’s Transportation magazine, Access.

It’s the usual “higher speeds kill” argument. Like all these arguments, they look at rural interstates, conclude that accidents went up a bit when the speed limit was raised, and say – voila! – higher speeds ees more deaths.

I get tired of this simplicity. When it comes from shills like the IIHS I can at least understand it as a matter of self-interest. Richard Retting wants the speed limits to be lower, because then you’ll get pulled over more and his employers can jack up your premiums. But the study in question comes from a bunch of OSHA and Public Health types. I expect them to be more rigorous.

So here’s the deal. Higher freeway speeds only increase injury when you define the bounds of your study at the edge of said freeway. As soon as you open it up to the network as a whole, there’s no effect, or – in many studies – higher speeds reduce injury. I’m not the first, or the third, or even the four-hundreth person to explain this. But as far as I know, it’s never been put graphically. Here then, a graphical explanation of the reason why higher speeds reduce injury.

Our story takes place somewhere deep in Pennsylvania:

It’s Friday, and after a long day of work Tony is ready for an evening of drinking and cornholing with his bar buddies. He leaves his house headed for the tavern in West Deliverance. A nationwide speed limit of 55mph is in full force, and Tony takes the shortest route available:

The roads are treacherous. In fact, statistically, rural two-lane highways are the most dangerous road imaginable. Combine high speeds, slow-moving farm equipment, lots of cross traffic, and often crappy geometry, and something like this is liable to happen:

Nevertheless, Tony makes it to the bar. After a rowdy night breaking bottles and sodomizing out-of-towners, he wakes up in the back of his pickup to realize: He’s going to be late for Mass. He needs to get back to the church, STAT. However, overnight, the traffic engineers have upped the speed limit on the Pennsylvania Turnpike to 75 miles per hour. It’s a bit out of the way, but Tony figures with luck, he can floor it and be back at the parish in the nick of time.

Tony’s a lot less likely to get into an accident this way. In fact, statistically, the PA Turnpike is one of the safest roads in the entire country, and easily bests anything else in PA, NJ, or MD. This in spite of being quite fast. Left-lane Turnpike speeds are often 80 on the PA side, 85 in the dualled parts of NJ.

Sure, the Pike is going to see more horrifyingly debilitating crashes at 80 than it would at 55. But we don’t care how many crashes some stupid road has, we care how many crashes Tony has – and Peggy, and Debbie, and Jim, and the rest of Tony’s friendly, upstanding neighbors. And the best way to keep them out of crashes is to entice them off the dangerous roads (rural two-laners) and onto the safe ones (freeways), by allowing high-enough speeds to justify going a little out of your way to use the safer facility.

Keep Minneapolis Minneapolis

I’ve never actually been to Downtown Minneapolis. My brother married a Richfielder, so I’ve spent a little time on the cloverleafs of southern Twin City suburbia. But never Downtown.

To that end, I don’t have really any policy prescriptions to offer, i.e., “Y’all should do THIS, and this, and that.” But after stumbling into the back-and-forth with the skyway dis bloggers, I was fascinated to read the comments on this Star-Tribune piece

- I like the skyways. Does that mean our street scene is different than midtown Manhattan — yes. And so what? This is the Twin Cities, we can be (should be) different. Also, skyways get people off the streets and intersections, making traffic flow much more smoothly.

- As others have stated, [the anti-skyway argument] ignores the businesses that have cropped up in the skyway and it also ignores how awesome skyways are in extreme hot and cold; which often defines Mn. I’m getting a little weary of urban planners that lack any pragmatism.

- Maybe Venice should copy us. The city is sinking so maybe they could do with a few skyways. From what I’ve read lately the argument against skyways is that they prevent window shopping. But aren’t the skyways all lined with shops at the moment? I don’t understand what’s wrong with them.

- The Professor is right. We should improve our skyway system, not write it off as a dead end. We can brag about our seasonal city – The Winter Skyway City and the Summer Street Scene City.

- Why try to be Venice or Copenhagen? Let’s just be Minneapolis.

These comments all share a basic common vein of “Keep Minneapolis Minneapolis.” People who generally like their city, like its unique features, want to improve on it.

Whereas the anti-skyway crew are full of platitudes about “world class cities,” and quote uppity Danes who say MN is “no longer up to the beat.”

Yeah.

And every east-coast urban planner is shocked, SHOCKED, that large parts of inner-ring Houston still have open ditch drainage. Yet ask any Heights homeowner whether they’d prefer to see the whole thing torn up for twenty-eight feet of curb and gutter and your answers would range from “no” to “hell no.”

Which is the way it should be. We’re not supposed to live in cookie-cutter cities.

So if you’ve got one side who says “I love my city, but I want to improve these facets” and you’ve got another side that says “My city is rubbish, it would be so much better if it was like Seattle, or Copenhagen” then you know what, I think the pro-skyway guys have won the argument.

This is Pap.

Someone read this and tell me what the hell he’s trying to say?

 http://tcsidewalks.blogspot.com/2012/01/climate-as-proxy-for-capital-within.html

I’m interested because there’s obvious similarities between the MN skyway and the Houston tunnel system, but I can’t grok this constant reference to “certain populations” and segregation of “distinct groups.”

Who’s being disenfranchised by the skyways? Black people? Bus riders? Democrats?

I never worked in Downtown, but I have been known to slip into the tunnel for kolaches or breakfast tacos…