Speediest and slowest states: Where does yours rank?

[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.

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.

Their number, 77, seems to be the average of 80, 75, and 75.  They seem to be saying that the highest rural Interstate speed limit is 80, the highest urban is 75, and the highest other limited access highway speed limit is 75.  Or perhaps urban and rural both have a maximum of 80 and 70 is the highest non-Interstate.  Either set of numbers averages the same.  Both the article and the map text refer to average top speed, not average of all speeds.  I think they're using the highest speed on each of the three types of highways and dividing the total by three.

I don't know about the veracity of the Idaho numbers, but my main point is that I think they're averaging three numbers, the maximum speed limit on each type of road.  In Texas, we have one stretch of state highway with a speed limit of 85, so therefore the top speed limit for non-Interstate highways is 85.  All of the lower speed limits don't matter.  If I-184 doesn't have the highest speed limit for its category, then its speed limit doesn't count toward the averages on the map.

[jeffandnicole]

Does Maine's 75 mph go thru rural and urban, and is it found on other, non-interstate highways?

Same with PA's 70 mph.

So while some may find the average of the 3 roads is what works, these 2 examples don't agree with that calculation.

[Jim]

Sad that something like this, where the methodology to gather and present the data is unclear at best and obviously incorrect at worst (see Maine, for example, as others have pointed out), can be published by cars.com and Yahoo..

[Roadrunner75]

Sad that something like this, where the methodology to gather and present the data is unclear at best and obviously incorrect at worst (see Maine, for example, as others have pointed out), can be published by cars.com and Yahoo..

Unfortunately, I think this is fairly typical of these sites.  Even Time this month, while they indicated sources in tiny print at the bottom, filled about a third of the magazine ("The Answer Issue"), with a bunch of lousy pie charts, graphs, percentages and factoids with very little context.  This is McNews at its worst.  Under "Safe Places to Live", Ocean County, NJ is listed as #1 Most Dangerous.  Hardly.  If you just browse through quickly, it may not be obvious at first that this is for natural disasters, and this is largely based on Sandy.  I'm sure New Orleans would've been rated #1 a few years ago.

[jeffandnicole]

Sad that something like this, where the methodology to gather and present the data is unclear at best and obviously incorrect at worst (see Maine, for example, as others have pointed out), can be published by cars.com and Yahoo..

Unfortunately, I think this is fairly typical of these sites.  Even Time this month, while they indicated sources in tiny print at the bottom, filled about a third of the magazine ("The Answer Issue"), with a bunch of lousy pie charts, graphs, percentages and factoids with very little context.  This is McNews at its worst.  Under "Safe Places to Live", Ocean County, NJ is listed as #1 Most Dangerous.  Hardly.  If you just browse through quickly, it may not be obvious at first that this is for natural disasters, and this is largely based on Sandy.  I'm sure New Orleans would've been rated #1 a few years ago.

And because they used a random time period for storms, destructive hurricanes such as Hurricane Andrew in 1992 weren't even included in the calculations.  Yet, they used a different random time period for earthquakes. 

[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.

Their number, 77, seems to be the average of 80, 75, and 75.  They seem to be saying that the highest rural Interstate speed limit is 80, the highest urban is 75, and the highest other limited access highway speed limit is 75.  Or perhaps urban and rural both have a maximum of 80 and 70 is the highest non-Interstate.  Either set of numbers averages the same.  Both the article and the map text refer to average top speed, not average of all speeds.  I think they're using the highest speed on each of the three types of highways and dividing the total by three.

I don't know about the veracity of the Idaho numbers, but my main point is that I think they're averaging three numbers, the maximum speed limit on each type of road.  In Texas, we have one stretch of state highway with a speed limit of 85, so therefore the top speed limit for non-Interstate highways is 85.  All of the lower speed limits don't matter.  If I-184 doesn't have the highest speed limit for its category, then its speed limit doesn't count toward the averages on the map.

I agree with that, but Idaho doesn't have any non interstates with a 75 MPH speed limit. US 20 northeast of Idaho Falls is the only freeway that isn't an interstate, and its speed limit is still 65.

The second notion might be possible, since Idaho has authorized (but hasn't actually posted!) 70 MPH speed limits off interstate, and I guess somebody could construe something like I-84 by Twin Falls as "urban" even though it really isn't.

But yeah, your theory sounds correct. I just hate seeing this thing quoted in the Idaho Statesman as a reason why Idaho might be a little crazy for 80 MPH speed limits.