State with the largest average distance between interstate exits

[HandsomeRob]

Calculated, of course, by dividing total interstate mileage by total number of interchanges.

My guess would be Vermont, anyone know where I might find the data to calculate this?

[bassoon1986]

Are we counting full interchanges only or each exit (ex: 5A/B, 5C)?

[Brandon]

I know that Illinois is no slouch in that department.  There are numerous sections where one can travel more than 10 miles between freeway interchanges (why limit it to interstates only?  a freeway is a freeway is a freeway!), even near Chicago.

[HandsomeRob]

Whatever I can find. I'd prefer to count each "interchange" separately - for example, exits 142A and 142B on I-90 here in Madison would be counted together as one interchange, since they both go to the Beltline, but exits 309A and 309B on I-94 in Milwaukee would be counted as two interchanges, since 309A goes to 35th Street and 309B goes to 26th - but I recognize that there are probably lots and lots of special cases that could make an exact determination of the number of interchanges difficult.

[bassoon1986]

Sounds good. I'll see what I can make of Louisiana

[vdeane]

I know that Illinois is no slouch in that department.  There are numerous sections where one can travel more than 10 miles between freeway interchanges (why limit it to interstates only?  a freeway is a freeway is a freeway!), even near Chicago.

It's already complicated enough to assess with just interstates (ex: I-180, I-587, Alaska).  Do we really need to add a debate about whether the Taconic is or is not a freeway on top of it?

Whatever I can find. I'd prefer to count each "interchange" separately - for example, exits 142A and 142B on I-90 here in Madison would be counted together as one interchange, since they both go to the Beltline, but exits 309A and 309B on I-94 in Milwaukee would be counted as two interchanges, since 309A goes to 35th Street and 309B goes to 26th - but I recognize that there are probably lots and lots of special cases that could make an exact determination of the number of interchanges difficult.

I can think of a zillion of the special cases just off the top of my head.  I-495 (NY) alone is essentially one giant pot of spaghetti.

[HandsomeRob]

Vermont has 320.22 miles of Interstates (per https://www.fhwa.dot.gov/reports/routefinder/table3.cfm), and by my count 53 interchanges, for an average of 6.04 miles/interchange.

vdeane: I'm pretty sure it's not going to be New York - let's call it a hunch.

[hotdogPi]

How about Maine? It's mostly I-95.

[Brandon]

OK, I get, for interstates only, an average of 3.54 miles for Illinois.  There is a total of 2,182.03 miles of interstate with approximately (by my count) 617 interstate interchanges.

This is heavily skewed by I-90, I-94, and I-290 in Chicago.  Taking those three out ups it to 4.20 miles between interchanges.

[hbelkins]

Vermont has 320.22 miles of Interstates (per https://www.fhwa.dot.gov/reports/routefinder/table3.cfm), and by my count 53 interchanges, for an average of 6.04 miles/interchange.

That's technically and accurately calculating it based on how it appears the question is phrased, but I have a feeling that the original poster is looking for something different, which I don't really know how to calculate.

It seems to me like I-81 in Virginia has an exit about every five miles or so.

[HandsomeRob]

Vermont has 320.22 miles of Interstates (per https://www.fhwa.dot.gov/reports/routefinder/table3.cfm), and by my count 53 interchanges, for an average of 6.04 miles/interchange.

That's technically and accurately calculating it based on how it appears the question is phrased, but I have a feeling that the original poster is looking for something different, which I don't really know how to calculate.

It seems to me like I-81 in Virginia has an exit about every five miles or so.

(I am the original poster)

[pianocello]

I calculated 3.41 miles/interchange in Iowa. It kinda surprises me that this is a lower average than Illinois.

[bassoon1986]

Ok for Louisiana there are 921.2 total miles of interstate, and I counted 359 exits. Give or take a few based on on our own opinions. That gives a ratio of 2.57 miles between each exit. I'm a little shocked to be honest. I pictured Louisiana's interstates a bit more rural. I'm sure I-110 and I-10 through New Orleans made that number lower.

I may attempt to be a glutton for punishment and try Texas....

[vdeane]

vdeane: I'm pretty sure it's not going to be New York - let's call it a hunch.

1. Those were just examples.  I'm sure the broader situations they cover apply to almost every state.
2. Wouldn't it be nice to see a ranking in the end?  To that end, we would want to standardize the measures so that we're not comparing apples to oranges.
3. The distance between exits in NYC on interstates is actually larger than one would think.  On the LIE for example, the distances between exits can be measured in miles even in Queens. (though I still wouldn't expect NY to be able to compete with a state that had few urban freeways period)

Anyone want to figure out a good way to measure Alaska?

[hotdogPi]

Anyone want to figure out a good way to measure Alaska?

There doesn't seem to be anything strange with it. They seem like normal interchanges.

[Kacie Jane]

Anyone want to figure out a good way to measure Alaska?

There doesn't seem to be anything strange with it. They seem like normal interchanges.

Then you don't know what an Interstate in Alaska is.

[DTComposer]

Not that I thought this would be anywhere near the top of the list, but my reckoning puts California at 2457 miles of Interstates with 1744 exits=1.4 miles per exit.

[keithvh]

FWIW, here is Nevada:

Interstate 80: 92 exits in 410.674 miles
Interstate 580: 19 exits in 30.09 miles
Interstate 15: 35 exits in 123.77 miles
Interstate 215 (only counting the portion between I-15 and I-515): 12 exits in 11.3 miles
Interstate 515: 18 exits in 20.54 miles

Total: 1 exit every 3.39 miles

[Alex4897]

Delaware scores an average of 2.25 miles between each exit with 40.61 total interstate miles and 18 (ish) exits.  Needless to say, we don't win.

[hotdogPi]

For Maine, it's almost exactly 4.

[hbelkins]

OK, here's the point I'm trying to make. I'll use I-24 in Kentucky as an example, since it has no partial exits. Also please note that I am not including the new Pennyrile Parkway exit in this determination.

There are 16 exits (not counting the new Pennyrile terminus, rest areas and weigh stations) on I-24. The first exit is Exit 3 and the last exit is Exit 89. Assuming that the distance between each exit is the exit number, the total distance between exits is 86 miles. 86 divided by 16 is 5.37.

However, the total length of I-24 in Kentucky is 93.373 miles. Divide that, and you get 5.84. There is a difference, although it is small. A long distance between the state line or the route's terminus and the first exit would skew that difference, such as the first exit on northbound I-75 is 11 miles inside the state.

[leroys73]

I was thinking Texas might have few exits because of I-10 out west.  However, I think I-35 and interstates east of it will bring the average down.  Good luck counting them bassoon.

[vdeane]

Anyone want to figure out a good way to measure Alaska?

There doesn't seem to be anything strange with it. They seem like normal interchanges.

Alaska has about 1,081.5 miles of interstate.  Most of these miles are two lane roads with at-grades and driveways.

[Kacie Jane]

However, the total length of I-24 in Kentucky is 93.373 miles. Divide that, and you get 5.84. There is a difference, although it is small. A long distance between the state line or the route's terminus and the first exit would skew that difference, such as the first exit on northbound I-75 is 11 miles inside the state.

But why would you not want to allow that 11 miles without an exit to "skew the difference"?

[vtk]

OK, here's the point I'm trying to make. I'll use I-24 in Kentucky as an example, since it has no partial exits. Also please note that I am not including the new Pennyrile Parkway exit in this determination.

There are 16 exits (not counting the new Pennyrile terminus, rest areas and weigh stations) on I-24. The first exit is Exit 3 and the last exit is Exit 89. Assuming that the distance between each exit is the exit number, the total distance between exits is 86 miles. 86 divided by 16 is 5.37.

However, the total length of I-24 in Kentucky is 93.373 miles. Divide that, and you get 5.84. There is a difference, although it is small. A long distance between the state line or the route's terminus and the first exit would skew that difference, such as the first exit on northbound I-75 is 11 miles inside the state.

But you're actually attempting to measure the average length of segments between interchanges, of which there are 15, not 16. That count adjustment should approximately offset the mileage adjustment.

Either method (93/16 or 86/15) seems valid to me. The difference is whether you're including the last few miles on the ends.