3 di's

[DandyDan]

5. I-680 and I-880 in Iowa.

I think that change was justified. The section of I-680 that became I-880 is primarily used by people going between Sioux City and Des Moines, whereas I-680 is simply a northwest loop of the Omaha area. There is some functionality for people in North Omaha to use I-880, but that is not the primary use. It really shouldn't have taken a flood to make it happen. If, in the 1970's, they had immediately switched it to I-880 from I-80N, no one today would probably ever notice.

[1995hoo]

....

EDIT:  Also...are there any other situations where a 3di enters a state its parent doesn't?  All I can think of off the top of my head is I-535 in WI.

I-287 has most of its length in New Jersey. I-87 doesn't enter New Jersey (nor any state other than New York).

[ethanhopkin14]

Which begs anothr question...how many states have a mainline interstate which runs less miles in its state than its 3dis?  I trust I-80 in CA easily meets that criteria.  I'd also nominate I-95 in MA.

I assume that is supposed to be I-95 in MD, not MA? Guess it could be either. If unsigned I-595 in MD is counted, it probably helps the case (No, I haven't measured)

I would also suggest I-95 in DC, but DC isn't really a state

I-95 in NY should qualify, I would think. I-78 in NY really qualifies

Trying a bigger state, I thought I-35 might pull this off in Kansas. But it is 215 miles, and its 3dis in KS add up to ~155 miles. 60 miles isn't too big a number, tho

EDIT:  Also...are there any other situations where a 3di enters a state its parent doesn't?  All I can think of off the top of my head is I-535 in WI.

I-129 and Nebraska

I-275 and Indiana

At present, one might argue I-269 around Memphis. I don't think I-69 is signed yet officially in TN

Honorable mention:

I-155 going from Arkansas to Tennessee.  Although I-55 obviously goes through Tennessee, going south to north, I-55 has long entered and exited the state by the time I-155 enters the state, so it almost qualifies.  Also, I-55 is longer in Tennessee, 15 miles over I-55's 12.

[1995hoo]

Following up on ilpt4u's comment about I-95 in Maryland: Said route has 108.9 miles in Maryland (mileage figures in this post are per Travel Mapping). Its 3dis are:

I-195 (4.05 miles)
I-295 (0.79 mile)
I-395 (1.19 mile for the mainline and 0.52 mile for the spur)
I-495 (41.27 miles if you count the entire overlap with I-95)
I-595 (19.65 miles)
I-695 (51.84 miles)
I-795 (9.04 miles)
I-895 (14.42-mile mainline plus two spurs of 0.54 and 2.35 miles)

Total 3di mileage, if you count all of I-495's overlap with I-95, equals 145.66 miles. If you subtract the overlap, the figure would still be greater than I-95's total mileage in Maryland because the overlap is around 27 miles. If you also subtract I-595 because it's unsigned, then you'd have I-95's mileage exceeding its 3dis.

[jmacswimmer]

Which begs anothr question...how many states have a mainline interstate which runs less miles in its state than its 3dis?  I trust I-80 in CA easily meets that criteria.  I'd also nominate I-95 in MA.

I-195 & I-295 in NJ have more total mileage (roughly 110 miles) than I-95 (roughly 89 if you include the western spur).

[I-55]

Trying a bigger state, I thought I-35 might pull this off in Kansas. But it is 215 miles, and its 3dis in KS add up to ~155 miles. 60 miles isn't too big a number, tho

Thinking of Kansas' 3di's, I have another question: What 3di's are unique in that they do something no other 3di does?

Example: I-235 KS is the only interstate (I think) that acts as a complete by-pass for another 3di, connecting to I-135 on both ends, and to no other interstate.

[Henry]

EDIT:  Also...are there any other situations where a 3di enters a state its parent doesn't?  All I can think of off the top of my head is I-535 in WI.

I-129 and Nebraska

I-275 and Indiana

At present, one might argue I-269 around Memphis. I don't think I-69 is signed yet officially in TN

And I-287 in NJ.

[1995hoo]

Trying a bigger state, I thought I-35 might pull this off in Kansas. But it is 215 miles, and its 3dis in KS add up to ~155 miles. 60 miles isn't too big a number, tho

Thinking of Kansas' 3di's, I have another question: What 3di's are unique in that they do something no other 3di does?

Example: I-235 KS is the only interstate (I think) that acts as a complete by-pass for another 3di, connecting to I-135 on both ends, and to no other interstate.

I-190 in New York is unique in being the only 3di that reaches the Canadian border.

EDIT:  Also...are there any other situations where a 3di enters a state its parent doesn't?  All I can think of off the top of my head is I-535 in WI.

I-129 and Nebraska

I-275 and Indiana

At present, one might argue I-269 around Memphis. I don't think I-69 is signed yet officially in TN

And I-287 in NJ.

Who woulda thunk it?

....

EDIT:  Also...are there any other situations where a 3di enters a state its parent doesn't?  All I can think of off the top of my head is I-535 in WI.

I-287 has most of its length in New Jersey. I-87 doesn't enter New Jersey (nor any state other than New York).

[jmacswimmer]

Thinking of Kansas' 3di's, I have another question: What 3di's are unique in that they do something no other 3di does?

Before the ICC was built, I think I-370 in MD may have been the only 3di that terminated at a metro station.

[ethanhopkin14]

Trying a bigger state, I thought I-35 might pull this off in Kansas. But it is 215 miles, and its 3dis in KS add up to ~155 miles. 60 miles isn't too big a number, tho

Thinking of Kansas' 3di's, I have another question: What 3di's are unique in that they do something no other 3di does?

Example: I-235 KS is the only interstate (I think) that acts as a complete by-pass for another 3di, connecting to I-135 on both ends, and to no other interstate.

I feel that any 3di that serves a downtown area while it's parent bypasses the city is unique.

I-635 in Texas begins at I-20, but terminates into SH-121, which should make it an odd 3di (I know the history of it were it used to be routed on the I-20 section south of Dallas)

[1995hoo]

I-475 passing Macon presents an unusual situation. It follows the conventional pattern of the 3di bypassing the city while the 2di (I-75) more directly serves the city itself, but what's unusual here is that the 3di covers a shorter distance for thru traffic than the 2di route does. More often a 3di loops around a city and covers a longer distance, but in Macon, you could visualize it as a bow and arrow situation where I-75 is the "bow" and I-475 is the "bowstring." I don't know off the top of my head whether this is truly "unique" in terms of there being no other place where that sort of thing happens, though, and I don't have time to look it up just now.

I-275 in Florida is an example of what "ethanhopkin14" notes in that I-75 bypasses Tampa and St. Petersburg to the east while I-275 serves them both directly (and then I-175 and I-375 connect to downtown St. Petersburg), although downtown Tampa is also served by a 1di (I-4).

[webny99]

I feel that any 3di that serves a downtown area while it's parent bypasses the city is unique.

Not the case here in Upstate NY. That happens in every major city: Buffalo (I-190), Rochester (I-490), Syracuse (I-690), Utica (I-790) and Albany (I-787).
2di's going through downtown are common in other parts of the country, but not here. It's either 3dis or no freeways at all.

[thspfc]

I have not read any replies yet, so these are my guesses:
1. 195
2. 95
3. I don't think so
4. Alaska, Wyoming (Cheyenne 180 doesn't count), Vermont (?), New Mexico
5. I don't think it's possible to have too many 3dis, but it is possible to have too many freeways (ahem, Kansas City, St. Louis, Cincinnati)
6. No idea

[Roadgeekteen]

I-475 passing Macon presents an unusual situation. It follows the conventional pattern of the 3di bypassing the city while the 2di (I-75) more directly serves the city itself, but what's unusual here is that the 3di covers a shorter distance for thru traffic than the 2di route does. More often a 3di loops around a city and covers a longer distance, but in Macon, you could visualize it as a bow and arrow situation where I-75 is the "bow" and I-475 is the "bowstring." I don't know off the top of my head whether this is truly "unique" in terms of there being no other place where that sort of thing happens, though, and I don't have time to look it up just now.

I-10 and I-12 de facto. Also I-470 and I-70 in WV.

[Roadgeekteen]

I have not read any replies yet, so these are my guesses:
1. 195
2. 95
3. I don't think so
4. Alaska, Wyoming (Cheyenne 180 doesn't count), Vermont (?), New Mexico
5. I don't think it's possible to have too many 3dis, but it is possible to have too many freeways (ahem, Kansas City, St. Louis, Cincinnati)
6. No idea

Vermont has I-189.

[jmacswimmer]

I-475 passing Macon presents an unusual situation. It follows the conventional pattern of the 3di bypassing the city while the 2di (I-75) more directly serves the city itself, but what's unusual here is that the 3di covers a shorter distance for thru traffic than the 2di route does. More often a 3di loops around a city and covers a longer distance, but in Macon, you could visualize it as a bow and arrow situation where I-75 is the "bow" and I-475 is the "bowstring." I don't know off the top of my head whether this is truly "unique" in terms of there being no other place where that sort of thing happens, though, and I don't have time to look it up just now.

I-10 and I-12 de facto.

And on a more local scale, I-10 and I-610.

[1995hoo]

I-475 passing Macon presents an unusual situation. It follows the conventional pattern of the 3di bypassing the city while the 2di (I-75) more directly serves the city itself, but what's unusual here is that the 3di covers a shorter distance for thru traffic than the 2di route does. More often a 3di loops around a city and covers a longer distance, but in Macon, you could visualize it as a bow and arrow situation where I-75 is the "bow" and I-475 is the "bowstring." I don't know off the top of my head whether this is truly "unique" in terms of there being no other place where that sort of thing happens, though, and I don't have time to look it up just now.

I-10 and I-12 de facto. Also I-470 and I-70 in WV.

I would quibble with I-10 and I-12 for purposes of this thread because both are 2dis.

I-470 is interesting–I couldn't tell just by looking at a map which route was longer there, though surely I-470 would be the "faster" route in any event due to being a better road with a higher speed limit. Turns out the I-70 route is three-tenths of a mile longer. Good catch!

I'm somewhat chagrined not to have thought of the I-610 example jmacswimmer mentions because my brother lives in New Orleans, so I feel like I should have known that one (though, to be fair, he moved there last year and I haven't been there since July 4 weekend in 1997).

[webny99]

I-475 passing Macon presents an unusual situation. It follows the conventional pattern of the 3di bypassing the city while the 2di (I-75) more directly serves the city itself, but what's unusual here is that the 3di covers a shorter distance for thru traffic than the 2di route does. More often a 3di loops around a city and covers a longer distance, but in Macon, you could visualize it as a bow and arrow situation where I-75 is the "bow" and I-475 is the "bowstring." I don't know off the top of my head whether this is truly "unique" in terms of there being no other place where that sort of thing happens, though, and I don't have time to look it up just now.

I-410 and I-10 in San Antonio qualifies in spirit (I-410 is about 2 miles shorter), although the weird situation with the northern I-35/I-410 junction means it's not very obvious visually, and there's not as much time savings as you might expect. Google actually recommends I-10 W>I-410 N>I-35 S>I-10 W.

You also have I-476 and I-81 in Scranton, PA.  I-476 is significantly shorter, if only there were better connectivity between the two roads (the story of PA's life, of course). This project aims to fix some of the connectivity issues and encourage the use of I-476 as a Scranton Bypass.

And of course, I-75 takes a triangular routing in the Detroit area, but the issue is that there's no 3di that connects on both ends. If only I-275 was completed to Clarkston, that would be a textbook example.

[sprjus4]

Trying a bigger state, I thought I-35 might pull this off in Kansas. But it is 215 miles, and its 3dis in KS add up to ~155 miles. 60 miles isn't too big a number, tho

Thinking of Kansas' 3di's, I have another question: What 3di's are unique in that they do something no other 3di does?

Example: I-235 KS is the only interstate (I think) that acts as a complete by-pass for another 3di, connecting to I-135 on both ends, and to no other interstate.

Not exactly an interstate, but VA-164 (should be I-164) in Hampton Roads connects to I-264 and I-664 on its endpoints, and serves as a shorter route than following I-264 to I-664.

I wouldn't necessarily call I-235 a "Bypass" , it's more of a loop. It would be inefficient to follow it compared to I-135 thru.

[webny99]

I-470 and I-70 in WV.

I-470 is interesting–I couldn't tell just by looking at a map which route was longer there, though surely I-470 would be the "faster" route in any event due to being a better road with a higher speed limit. Turns out the I-70 route is three-tenths of a mile longer. Good catch!

When I first read this, I overlooked "WV", and spent the time plotting out I-70/I-470 in Kansas, only to realize that that I-470 is 1.3 miles longer, and come back to this thread and see the detail I'd missed.

[texaskdog]

curious why they didn't go to 4 digits when they ran out of 3.  if they already had 9 x80s who not a 1080, 1180?  is it due to shield size?  or did they just not care.

[sprjus4]

I-475 passing Macon presents an unusual situation. It follows the conventional pattern of the 3di bypassing the city while the 2di (I-75) more directly serves the city itself, but what's unusual here is that the 3di covers a shorter distance for thru traffic than the 2di route does. More often a 3di loops around a city and covers a longer distance, but in Macon, you could visualize it as a bow and arrow situation where I-75 is the "bow" and I-475 is the "bowstring." I don't know off the top of my head whether this is truly "unique" in terms of there being no other place where that sort of thing happens, though, and I don't have time to look it up just now.

In the DC area, I-495 around the western side of the beltway is a shorter distance than following I-95 around the eastern side of the beltway.

In Hampton Roads, I-664 is a significantly shorter distance between Hampton and Bowers Hill as opposed to following I-64's arc around the eastern side of the metro.

[kphoger]

Trying a bigger state, I thought I-35 might pull this off in Kansas. But it is 215 miles, and its 3dis in KS add up to ~155 miles. 60 miles isn't too big a number, tho

Thinking of Kansas' 3di's, I have another question: What 3di's are unique in that they do something no other 3di does?

Example: I-235 KS is the only interstate (I think) that acts as a complete by-pass for another 3di, connecting to I-135 on both ends, and to no other interstate.

Not exactly an interstate, but VA-164 (should be I-164) in Hampton Roads connects to I-264 and I-664 on its endpoints, and serves as a shorter route than following I-264 to I-664.

I wouldn't necessarily call I-235 a "Bypass" , it's more of a loop. It would be inefficient to follow it compared to I-135 thru.

Funny, I've heard old-timers around here refer to 235 as "The Bypass".

[CNGL-Leudimin]

I have not read any replies yet, so these are my guesses:
1. 195
2. 95
3. I don't think so
4. Alaska, Wyoming (Cheyenne 180 doesn't count), Vermont (?), New Mexico
5. I don't think it's possible to have too many 3dis, but it is possible to have too many freeways (ahem, Kansas City, St. Louis, Cincinnati)
6. No idea

Check the very first reply to this thread, written by me. I already gave answers there.

[Roadgeekteen]

I-475 passing Macon presents an unusual situation. It follows the conventional pattern of the 3di bypassing the city while the 2di (I-75) more directly serves the city itself, but what's unusual here is that the 3di covers a shorter distance for thru traffic than the 2di route does. More often a 3di loops around a city and covers a longer distance, but in Macon, you could visualize it as a bow and arrow situation where I-75 is the "bow" and I-475 is the "bowstring." I don't know off the top of my head whether this is truly "unique" in terms of there being no other place where that sort of thing happens, though, and I don't have time to look it up just now.

In the DC area, I-495 around the western side of the beltway is a shorter distance than following I-95 around the eastern side of the beltway.

In Hampton Roads, I-664 is a significantly shorter distance between Hampton and Bowers Hill as opposed to following I-64's arc around the eastern side of the metro.

Should I-95 in DC be switched to the western side of the beltway?