Speediest and slowest states: Where does yours rank?

[bing101]

https://autos.yahoo.com/news/speediest-and-slowest-states--where-does-yours-rank-231406153.html

According to this article Texas has the fastest speed limit,while Alaska have the slowest  speed limits.

[hotdogPi]

"State highways". Including surface roads, apparently.

Even just counting freeways, it's not 65 for MA. MA has 55 sections, but it has nothing above 65.

[1995hoo]

I suppose DC does have a segment posted at 55 mph, but it's so minuscule it might as well not count–it's the 0.11-mile piece of the Beltway that crosses through DC airspace on the Wilson Bridge.

I was under the impression Alaska had at least some segments posted at 65, though (we didn't drive anywhere while there, so that's based solely on what I've read). A Google search confirms that. The article listed in the original post claims Alaska has nothing posted above 55. Makes me wonder where they got their data.

[kurumi]

The article says not all state highways are included:

... when you average the highest allowable speeds on its rural interstates, urban interstates and other limited access roads ...

Otherwise, if you averaged all state highways (i.e. CT 316 counts just as much as I-84), there's no way Connecticut (for example) averages 62 MPH posted. There are too many winding country roads.

However, since they're counting (usually) only freeways, and nearly everything has some 65 MPH sections (max allowed in-state), then the 62 MPH figure looks correct.

[hotdogPi]

The article says not all state highways are included:

... when you average the highest allowable speeds on its rural interstates, urban interstates and other limited access roads ...

Otherwise, if you averaged all state highways (i.e. CT 316 counts just as much as I-84), there's no way Connecticut (for example) averages 62 MPH posted. There are too many winding country roads.

However, since they're counting (usually) only freeways, and nearly everything has some 65 MPH sections (max allowed in-state), then the 62 MPH figure looks correct.

I was commenting on the picture saying "states ranked by average posted top speed on state highways" without mentioning limited access.

[oscar]

I suppose DC does have a segment posted at 55 mph, but it's so minuscule it might as well not count—it's the 0.11-mile piece of the Beltway that crosses through DC airspace on the Wilson Bridge.

I was under the impression Alaska had at least some segments posted at 65, though (we didn't drive anywhere while there, so that's based solely on what I've read). A Google search confirms that. The article listed in the original post claims Alaska has nothing posted above 55. Makes me wonder where they got their data.

Alaska has a lot of highway miles posted at 65mph, including both urban freeways and non-freeway "rural Interstates". Hawaii has nothing posted over 60mph.

Both states have many slow state highways, but even in that category Alaska can't top HI 360, posted for only 15mph on most of its ~35 mile length. 

[jeffandnicole]

How do they claim PA has a 70mph average top posted speed limit? They've only allowed 70mph for about a month now on only a few hundred miles of their highway system. And Maine is only 75 mph on the northern rural portions of 95. It's as their data used average speeds limits from some states, maximum speed limits from other states.

[GaryV]

And they've got MI at 70 - now maybe that's 69.7 rounded off - but there are some urban interstates and other freeways posted less than 70 mph, so the average can't be 70.

[algorerhythms]

It looks like they're using the highest speed on any particular highway, not the average of the speed limits. For example, they'd count all of I-68 in Maryland as 65, because that's the highest speed limit on I-68 in Maryland, ignoring the 40 mph limit in Cumberland.

Either that, or the numbers are rectally-derived.

[Duke87]

I can't fathom any way these numbers aren't anecdotal or otherwise arbitrarily sampled.

"Average posted top speed along state highways" implies that you would look at each road and figure out what the maximum speed limit anywhere along its length is, or perhaps look at each county and figure out what the maximum speed limit anywhere within its bounds is, and then average the results out. But by either of those measures, even if you only look at interstates, there is no way you get 70 for MI, PA, TN, or NC as these states all have interstates which don't achieve the state maximum anywhere along their length. Even if we look only at 2dis, PA still doesn't work.

[froggie]

Either that, or the numbers are rectally-derived.

Close enough.  It looks like what they did was take each state's top speed limit for urban Interstates, rural Interstates, and "other limited access highways", then averaged the three numbers.  But even then, they screwed up some numbers.

A rather poor methodology, IMO.

[Alex4897]

I think the 58 mph rating for DE is accurate, seeing as the range of speed limits for our freeways is limited to 50-65mph.

[Zeffy]

62 for New Jersey? Maybe, if you're only counting Interstates and limited access freeways. Except if it isn't an Interstate (US 1 through Trenton comes to mind), it always seems that the highest speed limit is 55. NJ 42 is 55 (from what I know), I can't imagine NJ 90 being over 55 either. The only roads I've seen in Jersey with a speed limit higher than 55, are Interstates. Those are 65.

[Alex4897]

62 for New Jersey? Maybe, if you're only counting Interstates and limited access freeways. Except if it isn't an Interstate (US 1 through Trenton comes to mind), it always seems that the highest speed limit is 55. NJ 42 is 55 (from what I know), I can't imagine NJ 90 being over 55 either. The only roads I've seen in Jersey with a speed limit higher than 55, are Interstates. Those are 65.

NJ 55 is signed as 65 mph IIRC.

[jeffandnicole]

62 for New Jersey? Maybe, if you're only counting Interstates and limited access freeways. Except if it isn't an Interstate (US 1 through Trenton comes to mind), it always seems that the highest speed limit is 55. NJ 42 is 55 (from what I know), I can't imagine NJ 90 being over 55 either. The only roads I've seen in Jersey with a speed limit higher than 55, are Interstates. Those are 65.

NJ 55 is signed as 65 mph IIRC.

So is Rt 18 and 2 (I think) other state routes, along with the non-interstate designated toll routes.

It looks like they're using the highest speed on any particular highway, not the average of the speed limits. For example, they'd count all of I-68 in Maryland as 65, because that's the highest speed limit on I-68 in Maryland, ignoring the 40 mph limit in Cumberland.

That can't be, since several states are shown as 58, 62, etc.

[algorerhythms]

62 for New Jersey? Maybe, if you're only counting Interstates and limited access freeways. Except if it isn't an Interstate (US 1 through Trenton comes to mind), it always seems that the highest speed limit is 55. NJ 42 is 55 (from what I know), I can't imagine NJ 90 being over 55 either. The only roads I've seen in Jersey with a speed limit higher than 55, are Interstates. Those are 65.

NJ 55 is signed as 65 mph IIRC.

So is Rt 18 and 2 (I think) other state routes, along with the non-interstate designated toll routes.

It looks like they're using the highest speed on any particular highway, not the average of the speed limits. For example, they'd count all of I-68 in Maryland as 65, because that's the highest speed limit on I-68 in Maryland, ignoring the 40 mph limit in Cumberland.

That can't be, since several states are shown as 58, 62, etc.

If my guess is accurate (more likely my second guess about rectal derivation is accurate...), then the way they did it was something like the following. Suppose we want to use the algorithm to get Oklahoma's number (to simplify it, let's only consider 2-digit interstates). The fastest speed limit on I-35 is 70, on I-40 is 70, and on I-44 is 75. If you average those numbers, you get about 72.

If that's actually how they did it, then it's a stupid algorithm, but "journalists" aren't going to put a lot of effort into a clickbait article.

[Mergingtraffic]

NY Putnam County has a road at 45mph when it enters CT in New Fairfield it slows to 30mph.

NY-55 is 55mph and when it changes to CT-55 at the state line it drops down to 40mph.
Same road!

[doorknob60]

Not sure if these are terribly accurate. Idaho, for example. 77 MPH? For interstates, absolutely. 80 MPH Rural (except I-90, which I believe is 70 MPH still), 65 MPH Urban. That means a majority of the interstate mileage is 80 MPH, so that number sounds about right. However, for everything non interstate, it maxes at 65 (though I think raising that to 70 is upcoming). So, they must only be counting interstates or something. Also, this shows the posted speed limits, but it would be interesting to see the actual driving speed. For example, nobody follows the speed limit in Oregon, but most people do in Idaho.

[Zzonkmiles]

I question South Carolina's 65 average.

Most of the interstates in SC are rural with a 70mph speed limit. The only exceptions are 60mph in Greenvville-Spartanburg, Columbia, Rock Hill, Florence and Charleston (I-85, 77, 26, 20, 95) with a 65mph area in North Augusta on I-20. The only place in the state (that I'm aware of) with a 55mph speed limit is in the congested area of I-26 where it crosses I-20 and I-126.

I also looked at Montana's 70mph average and laughed. Wasn't that the "reasonable but prudent" state regarding speed limits not too long ago?

I second the person who suggested these numbers were "rectally derived."

[corco]

What in the world? Sure, Idaho has an 80 MPH interstate speed limit in some places now, but it micromanages speed limits like crazy off-interstate. There is absolutely no way Idaho's average speed limit is higher than Montana, Wyoming, or Nevada. It's certainly not 77, 80 MPH on interstate and maximum 65 MPH off interstate != 77

I'd guess Montana has the highest average non-Texas speed limits- 75 MPH on rural interstates, 70 MPH on all rural highways even unpaved ones unless a speed study is conducted to justify a lower limit (a few instances of that on higher trafficked roads like US 93 south of Missoula and US 191 south of Bozeman, but not many).

The awesome part is that the anti-80 MPH in Idaho people (i.e. the Idaho State Police) are citing this study http://www.idahostatesman.com/2014/08/28/3344943_idahos-80-mph-brings-more-speeding.html?rh=1

(except I-90, which I believe is 70 MPH still)

Mostly 75 between Kellogg and Mullan now, but it didn't get the bump to 80. I think you're right though that for Idaho, it only includes interstate mileage. Even NHS mileage should drop it below 77 (US 95 has long stretches of 60 and 45).

[US 41]

I thought Colorado had higher speed limits on its 2 lane roads than New Mexico (65 compared to 60). Colorado's Rocky Mountains don't help the average speed limits though. New Mexico felt slow when I drove through it. Probably because there is nothing out there but deserts and mountains (on US 56 / 412, beautiful scenery though) and 60 mph just doesn't feel all that fast.

[roadman65]

That is weird considering Texas lets you do 75 on two lane roads and even Arizona lets you do 65.

Then again why is Arkansas at 55 mph when Oklahoma has 65 mph two lane roads right next to it?

[wxfree]

The article refers to "all three types of roadways" in Texas having an average of 78.3 mph, which is what's shown on the map.  The three types of roadways listed are "rural interstates, urban interstates and other limited access roads."  The map seems to be based on those, in spite of the more broad terminology in its text.  This would exclude the two-lane highways and some other roads, accounting for the high numbers.

In Texas, the example cited, the highest speed limit on rural Interstates is 80.  The highest on urban Interstates is 75.  The highest on other limited access roads is 85.  If we adjust the urban number to 70, leaving out the 75 mph speed zones in places like Midland and Abilene (which maybe aren't urban enough for their criteria), then the three numbers (80, 70, and 85) add up to 235, and dividing by three gives an average of 78.333, essentially the number quoted in the article and shown on the map.  It would seem that they calculated their numbers based on the highest speed limit on each type of roadway, not on each individual highway of the three types.

[corco]

The article refers to "all three types of roadways" in Texas having an average of 78.3 mph, which is what's shown on the map.  The three types of roadways listed are "rural interstates, urban interstates and other limited access roads."  The map seems to be based on those, in spite of the more broad terminology in its text.  This would exclude the two-lane highways and some other roads, accounting for the high numbers.

In Texas, the example cited, the highest speed limit on rural Interstates is 80.  The highest on urban Interstates is 75.  The highest on other limited access roads is 85.  If we adjust the urban number to 70, leaving out the 75 mph speed zones in places like Midland and Abilene (which maybe aren't urban enough for their criteria), then the three numbers (80, 70, and 85) add up to 235, and dividing by three gives an average of 78.333, essentially the number quoted in the article and shown on the map.  It would seem that they calculated their numbers based on the highest speed limit on each type of roadway, not on each individual highway of the three types.

That makes sense for Montana too, all limited access are either 65, 70, or 75, which averages to 70.

I'm still baffled on Idaho though, because there are lots of 65 MPH limited access highways (even if it's highest speed limit on a road, I-184 never gets higher than 65), so that 77 number just doesn't make sense.

[doorknob60]

(even if it's highest speed limit on a road, I-184 never gets higher than 65)

It doesn't change your point, but I don't think I-184 gets above 60 MPH. It seems to change as soon as the ramps leave I-84, and stays 60 all the way until the 45 zone near its eastern terminus. I don't think westbound it jumps to 65 until after the merge with I-84 either. But yeah, the 77 makes no sense either way.