Iowa speed limit article

[PurdueBill]

Although it's barely an article.  Very short and pretty much a rehash of press releases probably.

[pctech]

I'm sure auto insurance rates rise whenever speed limits rise. The carriers see increase risk of claims/losses.

Mark

[vdeane]

I'm sure auto insurance rates rise whenever speed limits rise. The carriers see increase risk of claims/losses.

Mark

Nah, it's just an excuse.  What's needed is for the "speed kills" lobby to shut up and stop telling their lies.  It's driving faster than conditions warrant that kills, not speed itself.

[texaskdog]

I'm sure auto insurance rates rise whenever speed limits rise. The carriers see increase risk of claims/losses.

Mark

Nah, it's just an excuse.  What's needed is for the "speed kills" lobby to shut up and stop telling their lies.  It's driving faster than conditions warrant that kills, not speed itself.

Amen!  Bad, inattentive drivers cause accidents, not speed itself.

[Special K]

I'm sure auto insurance rates rise whenever speed limits rise. The carriers see increase risk of claims/losses.

Mark

Nah, it's just an excuse.  What's needed is for the "speed kills" lobby to shut up and stop telling their lies.  It's driving faster than conditions warrant that kills, not speed itself.

So, it's not so much the speed as it is the speed?

BTW statistics clearly show a correlation between higher speeds and higher rates of fatality crashes.

[Scott5114]

Correlation does not imply causation.

[NE2]

Correlation does not imply causation.

What else could it imply here? That some unknown factor is both raising the speed limits and causing more crashes? That speed limits are raised after crashes increase?

[Revive 755]

BTW statistics clearly show a correlation between higher speeds and higher rates of fatality crashes.

And just how are those statistics broken out?  Do they distinguish between single vehicle crashes and multiple vehicle crashes?

[Scott5114]

Correlation does not imply causation.

What else could it imply here? That some unknown factor is both raising the speed limits and causing more crashes? That speed limits are raised after crashes increase?

The rate went from 227 to 250. While that is a 10% change, it is only a difference of 23, over the course of six and a half years. A change that small could easily be related to something else. Perhaps the change in the speed limit caused routing through Iowa to become more attractive than it was previously and traffic volumes increased by 10%. Perhaps there is some other change in road conditions that caused 3½ more people to die per year.

It also doesn't mention what happened to the rate of overall crashes, or even the number of crashes resulting in fatalities, just the number of fatalities. The total number of crashes could have gone down while fatalities went up.

Point is, the article doesn't have enough information to establish that the increase is caused by the raise in speed limit. Just that it happened at the same time. It is possible that it did cause it, and that seems to be what the writer wants to get across, but without more data that conclusion is specious.

[NE2]

So what you're saying is that there may actually not be correlation due to not enough data. Why didn't you say that in the first place, rather than repeating a cliche?

[Scott5114]

Because there is a correlation. Speed limits went up, at the same time, so did the number of fatalities. That's a correlation, is it not? What I am saying is that the article doesn't have enough data to show that the speed limits going up caused the fatalities, since it could be caused by higher traffic volumes, other changes in road conditions, a spike in DUIs, more people riding together in the same number of cars that are crashing, etc. Really the cause could be any manner of random noise since it equates to an average of only 3½ extra deaths per year–without breaking the data down, for all we know, highway fatalities stayed the same but for the fact that a bus crashed into a river one year and killed 23 people.

[NE2]

Because there is a correlation.

A correlation is a relation between two variables. Unless I'm completely misremembering statistics, you can't get a correlation from a single data point. You need a number of data points, which gives you a certain probability of correlation vs. random noise.

[Brandon]

The total number is really a worthless statistic.  The number that matters is the one per vehicle miles traveled.

[SP Cook]

BTW statistics clearly show a correlation between higher speeds and higher rates of fatality crashes.

Incorrect. 

Following the partial and then full abandonment of underposting under the NMSL, traffic mortality declined.

[NE2]

BTW statistics clearly show a correlation between higher speeds and higher rates of fatality crashes.

Incorrect. 

Following the partial and then full abandonment of underposting under the NMSL, traffic mortality declined.

Correlation does not imply causation.

[pctech]

What about the increased fuel consumption that comes with increased speed?

[Scott5114]

How would that affect fatality rates?

[Special K]

How would that affect fatality rates?

Heart attack at the pump.

[formulanone]

Typically, a higher speed accident causes more expensive crashes, and the said equipment to keep you safe in accident is getting more expensive.

Warning: Correlation does not imply I've worked at a body shop before.

[kphoger]

Higher speeds obviously correlate to more fatalities.  Braking distance is increased, force of impact is increased, that's commonsense.  Hit a car at ten miles an hour, and you're a lot less likely to die than if you hit a car at eighty miles an hour.  The huge gap in statistics is that most of the 'speed-related' accidents recorded are actually driving too fast for adverse conditions, in which case the posted speed limit is a moot point, yet there is no statistical breakdown between over the posted limit and too fast for adverse conditions:  everything is just lumped together under 'speed-related', and then those numbers are used to talk about posted speed limits.

All that is to say that there is very likely a correlation between raising a speed limit and seeing more fatalities, but that the strength of that correlation is just as likely (or more) highly overblown, and I don't think there's a way to determine by how much.

[vdeane]

So, it's not so much the speed as it is the speed?

No.  There is a VERY BIG difference between driving too fast for conditions and driving faster than a number some politician pulled out of his rear.  Take the Thruway for example.  On a day with good driving conditions, it's safe to drive 80 down it.  In the middle of a snow storm, it's not even safe to do 30.  The speed limit is 65 regardless.  In fact, I can't think of any situation where 65 is the maximum safe speed for the Thruway.

Or take the New Jersey Turnpike.  On any given day, traffic is moving at 80 if conditions allow for it.  Is this legal?  No.  Is it safe?  Yes.

Arbitrarily low speed limits actually make the roads less safe by making the people who actually pay attention speed limits drive slower while everybody else drives the same way they always do.  Roads are safest if everyone drives the same speed, but arbitrarily low limits cause the difference between speeds to be greater.

What about the increased fuel consumption that comes with increased speed?

Who cares?  The way to solve the oil issue is to find an alternative way to power cars, not to make life worse for drivers.  Sadly, people like to ignore things until they can't; otherwise, we'd all be driving electric cars by now.

All that is to say that there is very likely a correlation between raising a speed limit and seeing more fatalities, but that the strength of that correlation is just as likely (or more) highly overblown, and I don't think there's a way to determine by how much.

Actually, Detroit proved the opposite when they went from 55 to 70.  The Ohio Turnpike did too when they went from 65 to 70.

[agentsteel53]

Roads are safest if everyone drives the same speed

almost, but not quite.  roads are safest when each lane is moving faster than the one to its left.

people driving in three-abreast formation, at precisely the posted speed limit, are absolutely not safe at all.  (see: Oregon)

[kphoger]

Roads are safest if everyone drives the same speed

almost, but not quite.  roads are safest when each lane is moving faster than the one to its left right.

people driving in three-abreast formation, at precisely the posted speed limit, are absolutely not safe at all.  (see: Oregon)

Unless you were talking about England.

[agentsteel53]

Unless you were talking about England.

nope, dyslexic! 

[Brandon]

Higher speeds obviously correlate to more fatalities.  Braking distance is increased, force of impact is increased, that's commonsense.  Hit a car at ten miles an hour, and you're a lot less likely to die than if you hit a car at eighty miles an hour.  The huge gap in statistics is that most of the 'speed-related' accidents recorded are actually driving too fast for adverse conditions, in which case the posted speed limit is a moot point, yet there is no statistical breakdown between over the posted limit and too fast for adverse conditions:  everything is just lumped together under 'speed-related', and then those numbers are used to talk about posted speed limits.

All that is to say that there is very likely a correlation between raising a speed limit and seeing more fatalities, but that the strength of that correlation is just as likely (or more) highly overblown, and I don't think there's a way to determine by how much.

Actually, there is.  Total fatalities is a meaningless statistic.  You need to look at and compare fatalities per mile driven.  That rate has been falling fairly steadily since the 1960s with and without the NMSL.

Plus, the goal of zero fatalities is idiotic.  To have a rate of zero is to wish for a risk-less society, and there is no such thing.