Most and Least Important 3dis?

[TheHighwayMan3561]

I'd say 494 is a pretty important 3di - parts of it carry nearly as much traffic as I-94 in MSP.

[ekt8750]

Most: I's-495 (MA, NY, MD, VA), 195 (RI, MA) 390 (NY), 490 (NY), 287 (NY, NJ) 280 (NJ), 295 (NJ, DE) 476 (PA), 195 (NJ)

Least: I's-384 (CT), 495 (DE, PA), 895 (NY), 990 (NY), 587 (NY), 564 (VA), 189 (VT)

I have to disagree with you DE's 495 (which does not enter PA btw). It is a great high speed bypass of Wilmington which causes backups on 95 all the time, not to mention the differences in speed limits, higher capacity on 495, etc.

[DandyDan]

One I personally think has to be fairly useless is I-129. The 3 or 4 times I was ever on it, there was no traffic.

[PurdueBill]

Most: I's-495 (MA, NY, MD, VA), 195 (RI, MA) 390 (NY), 490 (NY), 287 (NY, NJ) 280 (NJ), 295 (NJ, DE) 476 (PA), 195 (NJ)

Least: I's-384 (CT), 495 (DE, PA), 895 (NY), 990 (NY), 587 (NY), 564 (VA), 189 (VT)

I have to disagree with you DE's 495 (which does not enter PA btw). It is a great high speed bypass of Wilmington which causes backups on 95 all the time, not to mention the differences in speed limits, higher capacity on 495, etc.

495 is indeed often very useful when 95 is a mess.  It would be a better routing of 95 itself, but they've already played that game in the past.

It is interesting that on the PA I-95 SLD, there is mention of "ramp to I-495 Delaware" on page 53 (note, the pages are backwards in the file) so indeed despite the gore point being before the state line, the road isn't 495 until the state line.  Northbound, the merge happens south of the state line, so no mention of 495 on the northbound side of the straight line diagram.

[hm insulators]

Just out of curiosity, what would y'all say are the most and least important 3dis, based on the traffic they carry and the areas they serve?

Personally, I'd say I-405 in CA or I-285 in GA are some of the most important 3dis, with some of those 3dis that are just glorified exit ramps being some of the least important, along with maybe I-759 in AL.

Also I would add I-110 and even I-210 in southern California.

[Takumi]

Most: I's-495 (MA, NY, MD, VA), 195 (RI, MA) 390 (NY), 490 (NY), 287 (NY, NJ) 280 (NJ), 295 (NJ, DE) 476 (PA), 195 (NJ)

Least: I's-384 (CT), 495 (DE, PA), 895 (NY), 990 (NY), 587 (NY), 564 (VA), 189 (VT)

564 is short, but far from unimportant.

[catsynth]

I guess the most important 3di will be the one that you use the most

I-580 in CA is a de-facto 2di and part of our main Interstate connection from SF to LA.
In NYC, I-278 may be a mess, but it's useful for getting around 4 out of 5 boroughs.
Also in the NY metro area, I-287 is quite useful, esp. for bypassing the city.
In LA, I-405 and I-110/CA 110 are major essential routes.

[Charles2]

Least? Why not I-359 in Tuscaloosa, since it's multi-plexed with US-11 and AL-69 for its entire route.

[adventurernumber1]

For the most important 3di, I would have to say Interstate 580 (CA). It, along with Interstate 476 (PA) and Interstate 390 (NY), essentially functions like a 2di. There are some 3dis that are not like this, but they are indeed still very important - usually beltways, partial beltways, or urban interstates such as I-405 (CA), I-110 (CA), I-495 (NY), I-495 (MA), I-495 (VA/MD), I-285 (GA), I-294 (IL), I-287 (NJ/NY), and more. However, my pick for the most important 3di will remain I-580 in California. It truly is just so incredibly important - like others have said, it is a vital interregional corridor, it is vital just the same for locals and commuters, and it is very long and very used, and more.


For the least important 3di, I truly cannot decide. There are so, so many "glorified exit ramp" 3dis, some of which are quite important, and some of which are not so important. In my opinion, there really are a lot of candidates for the least important 3di, but I personally, at this moment, cannot narrow it down to one.

I know Interstate 180 (IL) had an initial purpose which is no longer relevant. I think someone said that even today, I-180 may be part of a potential corridor to Peoria, but I don't know enough about that to comment on it myself. I-180 is definitely in the realm of least important, but it does, of course, have its arguments.

Regarding Interstate 564 (VA), someone mentioned it, but I would have to agree with someone else in arguing that the interstate is probably actually quite important. I just looked at I-564 on Google Maps, and it at least looks like there is a whole lot going on right around where I-564 ends. I don't know what exactly it is (maybe someone can elaborate on that), but it definitely looks pretty big (perhaps a port of some sort, but I haven't a clue). Interstate 564 could potentially be one of the (or the) most important very short three-digit interstates.

So once again, there are probably a larger number of "least important" 3dis than "most important" 3dis, because of the sheer number of different 3dis that have little importance, comparatively. So this is seemingly why it is much harder to pick a "least important 3di" than it is to pick a "most important 3di."

[oscar]

Regarding Interstate 564 (VA), someone mentioned it, but I would have to agree with someone else in arguing that the interstate is probably actually quite important. I just looked at I-564 on Google Maps, and it at least looks like there is a whole lot going on right around where I-564 ends. I don't know what exactly it is (maybe someone can elaborate on that), but it definitely looks pretty big (perhaps a port of some sort, but I haven't a clue).

It's only a huge Naval base. Since it's the "National System of Interstate and Defense Highways", the freeway link to the base is a particularly appropriate 3di.

Military needs also explain Hawaii's Interstate network, thousands of miles from any other state. However, Hawaii's only 3di isn't all that important even though H-201 serves some of the many military bases in the Honolulu area.

[bing101]

I-980 Oakland,CA is least important due to the fact that its a continuation of CA-24 and was intended to be part of the Southern Crossing but that issue has been outright out of discussion anyways.

[kkt]

I-980 Oakland,CA is least important due to the fact that its a continuation of CA-24 and was intended to be part of the Southern Crossing but that issue has been outright out of discussion anyways.

980 still carries quite a bit of traffic.  If it were suddenly gone, lots of people would miss it.

The obvious least important is Wyoming 180.  It's not even a freeway, and there are other, more appropriate route numbers concurrent with it.