Speed Limit Biases?

Here I am going to cover a really terrible study to try to boil down why this is terrible reasoning.

I ran into this study after reading a blog post. [I forget the post, if you know where this is, I’d love to give you credit.]

Basically, the blogger was talking about how the city wanted to raise the speed limit based upon a twenty year old paper: http://www.ibiblio.org/rdu/sl-irrel.html: Effects of Raising and Lowering Speed Limits by U.S. Department of Transportation Research, Development, and Technology
Federal Highway Administration Turner-Fairbank Highway Research Center 6300 Georgetown Pike McLean, Virginia 22101-2296.

Since I have had success in the past with reading papers and interpreting my own way, I thought that I’d give this one a shot.

Turns out, that, to quote an old friend, “this paper confirmed everything I had been saying all along.” 🙂

Just kidding.

Actually, this paper is a little better than tautology.

First of all, the paper wants to look into two problems: people who speed and the accidents that they cause.

Both of these things are not problems to cyclists.

I realize that this may surprise you.

While fast moving traffic is worse for cyclists, by “speeding” the authors meant that “motorists who drive faster than the posted speed limit.”

To paraphrase another old friend, “Cyclists are dyin’, you know why! The speed limits are too damned high!”

Joking aside, in the past year alone, many of the cyclists and motorists who were involved in fatal collisions this year in San Diego were FOLLOWING ALL THE TRAFFIC LAWS. That’s right, FOLLOWING THE TRAFFIC LAWS DOES NOT PROTECT ONE FROM GETTING INTO FATAL COLLISIONS.

Thus, the whole notion of speeding is idiotic because it only addresses a fake made up problem.

The way to calm traffic is to tame the street: narrow the lanes, add more stops, encourage pedestrians and cyclists, and for the love of god stop persecuting jay walkers and wrong way cyclists. Calmer traffic == less major injuries and fatalities.

But, no, this paper wants to set it up as a “compliance” problem as if the government is burdening the poor motorist too much by asking her to SLOW THE FUCK DOWN.

But the madness continues!

The second problem this fine paper addresses is the problem of accidents.

Again, “accidents” are not the problem.

Pain is a teacher. We all need to fall down to learn. Part of the problem with motoring is that it doesn’t allow you to bump into someone and get hurt and learn something. Collisions are either mitigated in the motorist’s favor via clearing the roadside, guard rails, air bags, crumple zones and so on or they are totally deadly. No chance to learn in either case because there’s no physical pain.

I got hit in the head by a surfboard last weekend. Guess who’s signing up for a crash coarse (no pun intended) in surf board control?

The problem for cyclists are collisions with high speed motor vehicles. Again, this paper does NOTHING to address this problem at all. They are merely talking about collisions between two motor vehicles, only.

So if someone raises this paper in a meeting where they claim that it suggests that accidents can be mitigated by increasing the speed limit, mention that no it does not. It says that it will protect scofflaw motorists from legal repercussions by changing the law to the law breakers failure. I mean, we don’t solve the murder problem by legalizing certain forms of murder do we? If there’s a good reason for society for people to slow down on a road why are we ignoring that?

Second, this paper does NOT ADDRESS CYCLISTS AND PEDESTRIANS. Therefore, it is useless when referring to pedestrians and cyclists. In fact, I’d argue that it puts them at greater risk, and it even admits it in its round about way:

“A review of early vehicles speed legislation in the United States suggests that regulations were established to improve public safety.[1] The rational for government regulation of speed is based on the fact that unreasonable speed may cause damage and injury.”

Here’s a great quote, the kind I had expected.

Note that this quote is NOT found in the summary nor to the people who present this paper know about it:

“The analysis further indicates that injury accidents increased irrespective of whether the speed limits were raised or lowered. Because the number of accidents at the comparison sites was less than 240 in the before and after period, injury accident estimates were based on the before and after analysis which does not control for nonrandom factors that can affect the results. Consequently, the accident estimates for injury accidents should be treated with caution. This precaution is also applicable to the results for the other groups listed in table 10 where the safety effects were estimated with the before and after method. ”

We put things in all caps for those who are merely scanning for things to argue about or for data to back up their prejudices:


Thus, it lowering speed limits didn’t have a big increase in accidents. However, the SEVERITY of accidents where people drive slower does go down.

However, they mostly do NOT drive slower when the speed limit is lowered.

The paper mentioned elsewhere that with a lower speed limit the number of scofflaw motorists increased to over fifty percent. Thus according to this paper: FIFTY PERCENT OF MOTORISTS (OR MORE) ARE SCOFFLAWS.

When these people get on bicycles, do we expect them to follow all traffic laws? No. Thus, the whole notion of scofflaw cycling as being separate from scofflaw motorists is bunk. A scofflaw is a scofflaw, it doesn’t matter what they are riding or driving.


First this paper is a piece of shit propaganda. Second, this paper can be used against those who wrote it by reading it carefully.

Thus, you should print out this paper, highlight the relevant parts and bring it to the next meeting so the next time someone misquotes this mess, you have your quotes ready too.

You’re welcome.


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