The data from Montana always struck me as interesting. It's not an awful lot of data presented in this report [1], but there was a substantial increase in traffic fatalities when Montana shifted from "Reasonable and Prudent" speed limits to posted-and-enforced speed limits.
I then found this report [2] which indicates that yearly fatalities are approximately double of what they were in the late 90s (and is now around the third highest fatality rate in the nation [3]). It's a good guess that traffic volume has gone up, but safety technology has improved as well, so there are a number of variables that have to be accounted for. The differences are certainly stark enough that it merits some consideration, though.
Nationwide, traffic fatality rates have been on a steady downward march over the last couple of decades [4], so Montana's tremendous leap in fatalities is absolutely anomalous. If I was debugging it, I'd start looking at what changed around that time. On the face, it certainly looks like posting and enforcing speed limits made the roads less safe, though.
The source looks somewhat unreliable and biased. I looked up FARS data for
1998,1999,2000 for number of fatal-crashes in Montana (state), for (nhtsa)Roadway
Functional Classification=Principal Arterial - Interstate and get the following
figures for crashes by month:
1998-4,0,2,4,5,1,5,4,0,0,3,2,30
1999-2,2,4,2,1,0,2,9,4,2,1,5,34
2000-2,1,4,5,1,5,3,3,3,1,4,4,36
However the "study" has
1998-4,0,2,4,5,1,5,4,0,1,3,2,31
1999-2,2,4,2,1,0,2,7,4,1,1,4,30
2000-4,2,8,5,2,7,7,3,4,1,6,7,56
I've removed the section, it's obviously made up numbers for 2000 for interstates
to suit an argument, nowhere near fact. There is a reason for the use of reliable
sources in Wikipedia and this is a case in point. Alex Sims (talk) 10:13, 25
January 2011 (UTC)
See what someone with an authoritative sounding domain name can do!
I was looking for government numbers for those years, but didn't have much luck. Thanks for the FARS keyword - that looks like it should have the datasets I need! I'm going grab and parse them and see if there's an actual difference in the data.
I somewhat doubt the data was made up, but it's possible that the roadway classifications were chosen in such a way that the datasets supported the point.
No I think the so called paradox was made up, To verify:
http://www.nhtsa.gov/FARS
Select tab "Run a Query Using the FARS Web-Based Encyclopaedia"
"Query Fars DATA" which takes you to
http://www-fars.nhtsa.dot.gov//QueryTool/QuerySection/SelectYear.aspx
For each year 1998,1999,2000
Select Query Year, e.g. 2000, then Submit
In the top section Tick
“Roadway Function Class”
and “Month”, then Submit
Select State: Montanta, and RFC Roadway Function
Class “Rural-Principal Arterial-Interstate”
Select Univariate Tabulation
Select Variable - Crash Month and “Show Zeros” Yes
I've always loved this example. I lived in MT pre, during, and after this experiment. We went from:
- 65 Mph
- "Reasonable and prudent" daytime speed
- 75 Mph daytime speed
During the reasonable and prudent period, I think many people still had an internal model of 65 Mph. Certainly many people did drive faster. In my younger days, friends and I would find straight, empty sections of highway to flirt with death. But... many many people still set their cruise control to 65.
Case in point, my parents and the parents of many of my friends were careful to clarify that "reasonable and prudent means 65 mph, or you will have your driving privileges revoked." I was out from under the parents' roof by the time things went to 75, but I know my own highway averages went up with the codification of 75 mph.
Very interesting. How well do you think that 65 MPH internalized limit (during R&P) mapped to the 85/15% split as described in the original article?
Do you have any other insights into other factors that might have contributed to the change in fatalities, or do you think it was just as simple as "people are driving 10 MPH faster on average", with correlated increases in fatality rates?
That's a really interesting question. My unscientific hunch is that there were two different populations of drivers on MT roads at the time. Lets call them the daredevils and the 65-ers.
I'd bet that among the 65-ers, it probably did map pretty well--or at least approximately as well as it did in states that retained a 65mph speed limit. You might have seen a few people creep up maybe instead of setting your cruise to 72 mph, in hopes of skirting a ticket, you set it to 75 because... round number?
The daredevils are pretty much by definition going to be exceeding the speed limit, but they could arguably be described as a different group, i.e. one that didn't internalize the 65 mph. A common narrative amongst Montanans of the time was that out-of-state types (most likely Californians, horror!) were coming to MT to treat our roads like a raceway. I'm sure that probably did happen to some extent, though who knows if it was actually a common occurrence.
I then found this report [2] which indicates that yearly fatalities are approximately double of what they were in the late 90s (and is now around the third highest fatality rate in the nation [3]). It's a good guess that traffic volume has gone up, but safety technology has improved as well, so there are a number of variables that have to be accounted for. The differences are certainly stark enough that it merits some consideration, though.
Nationwide, traffic fatality rates have been on a steady downward march over the last couple of decades [4], so Montana's tremendous leap in fatalities is absolutely anomalous. If I was debugging it, I'd start looking at what changed around that time. On the face, it certainly looks like posting and enforcing speed limits made the roads less safe, though.
[1] http://www.hwysafety.com/hwy_montana.htm
[2] http://www.mdt.mt.gov/publications/docs/brochures/safety/hsp...
[3] http://missoulian.com/news/local/report-montana-highway-deat...
[4] http://en.wikipedia.org/wiki/List_of_motor_vehicle_deaths_in...