Most and Least Important 3dis?

[freebrickproductions]

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.

[hotdogPi]

A thread that I started in 2015 about most important: https://www.aaroads.com/forum/index.php?topic=14914

There have been several threads that are "useless 3dis", "3dis that are just ramps", etc., but this is slightly different, so discussion can continue here.

[freebrickproductions]

A thread that I started in 2015 about most important: https://www.aaroads.com/forum/index.php?topic=14914

I had forgotten about that one.

[sparker]

Since the threads haven't been merged yet (good idea, mods!), I'll put my two cents worth in right here.
MOST IMPORTANT:
I-580 (CA); it does double-duty as part of a major interregional connector as well as an equally major commute artery (and perennial headache!).  Relief routes (such as the northerly projected 4/239 combination and a full-fledged 152 freeway over Pacheco Pass) would be more than welcome! 

Still working on that "least important" concept!

[jp the roadgeek]

Least important has to be I-180 in Illinois to serve a village (Hennepin) of less than 1000 people. 

Most important would be three of the I-495's (DC Beltway, LIE, MA.  Sorry DE, NC, and ME)

[CNGL-Leudimin]

Least important has to be I-180 in Illinois to serve a village (Hennepin) of less than 1000 people. 

Most important would be three of the I-495's (DC Beltway, LIE, MA.  Sorry DE, NC, and ME)

FTFY. Agree with IL I-180.

[Flint1979]

Least important is by far I-180 in Illinois. It goes from I-80 in the middle of nowhere Illinois to Hennepin a very small town of about 800 people. But in it's defense it was built to connect I-80 to a steel plant.

[sparker]

Now that I've had some time to think about it -- since the N-S portion of I-180 in IL at least serves as a connector to IL 29, the major road north from Peoria, it gains a bit of utility in that manner.  I'd have to say that the least important 3di would be I-194 in ND; it's only a short segment of the Bismarck south loop; if it were to only be numbered the same as the loop's remainder, nobody would miss it at all (even though it's the only 3di in ND!).

[ilpt4u]

Now that I've had some time to think about it -- since the N-S portion of I-180 in IL at least serves as a connector to IL 29, the major road north from Peoria, it gains a bit of utility in that manner.

Having lived in Peoria for a short bit, while yes IL 29 can and is utilized for this, the main route for Northbound traffic is getting across the IL River and getting East to either I-39 or I-55 (usually via IL 116 or US 24), not following the River up to I-180 via IL 29. But I guess it is partially dependent where in the Peoria area you are and where you are going in terms of a "Point North"

If IL 29 gets a Freeway, or even Expressway, upgrade, then maybe I-180 might be more useful. Otherwise, I renominate for "worthless"

[Quillz]

Least important is I-180 in Wyoming.

[ilpt4u]

Least important is I-180 in Wyoming.

There is an argument to be made there -- since that I-180 is an Interstate in name only, and doesn't even try to conform to Freeway/Grade Separation requirements. It is essentially a City Arterial with a fancy designation. It does still serve WY's largest city, Cheyenne

I'm sure by traffic counts, it is much more utilized than the IL I-180, which is basically a Freeway to nowhere...

[Rothman]

Have to agree with ilpt4u.  Just because it is an arterial doesn't mean people don't use it.

[Bickendan]

Now that I've had some time to think about it -- since the N-S portion of I-180 in IL at least serves as a connector to IL 29, the major road north from Peoria, it gains a bit of utility in that manner.  I'd have to say that the least important 3di would be I-194 in ND; it's only a short segment of the Bismarck south loop; if it were to only be numbered the same as the loop's remainder, nobody would miss it at all (even though it's the only 3di in ND!).

If I-194 were extended across the bridge and actually were signed, it'd start to live up to being somewhat useful.

[kkt]

I-705 in Washington is basically an exit ramp for downtown Tacoma.  1.5 miles.

[Flint1979]

I-705 in Washington is basically an exit ramp for downtown Tacoma.  1.5 miles.

Basically the same as I-375 in Detroit.

[GenExpwy]

A couple of unimportant ones in New England to consider:

I-195, Saco, ME. About a 2-mile bypass of Saco (pop. 18000), which quickly becomes 2-lane ME 5, passing thru residential areas en route to Old Orchard Beach (pop. 8000). Rand McNally doesn't bother labeling it with an I-195 shield.

I-393, Concord, NH. Bypasses Concord, but then just quits halfway to such metropolises as Gossville and Epsom. Entire length is an overlap with US 4 and 202.

[ColossalBlocks]

Interstate 155 in Missouri/Tennessee is pretty pointless as it multiplexes with US 412 for it's entirety.

[hbelkins]

Interstate 155 in Missouri/Tennessee is pretty pointless as it multiplexes with US 412 for it's entirety.

I-155 came first.

[english si]

There's also far more useless 3dis wholly concurrent with US routes. I-180 (also concurrent with I-25 BL and US87 Bus) in WY as an example.

[bing101]

I-880 and I-710 both freeways are important because of Truck Traffic because of the destinations to the Ports. 

[sparker]

I-880 and I-710 both freeways are important because of Truck Traffic because of the destinations to the Ports. 

I-880 derives much of its truck traffic from a shunt over (shudder) I-238 from I-580, due to the fact that I-580 from the I-980/CA 24 interchange east to the Oakland city limits is closed to truck traffic; the I-880/238 combination functions as a "truck 580" as a result, funneling I-5 commercial traffic to & from the warehouse/port areas of Oakland and environs.   

[machias]

I-790 in New York. It doesn't even have it's own roadway and it barely gets mentioned on signs, though the latest efforts on that have improved visibility.  Ask nearly anyone in Utica for directions to I-790 and they won't know what you're talking about.

[bing101]

I-305 Sacramento because of Downtown Sacramento Traffic is important. Plus I-680 from Benicia to San Jose portion because of east bay commuter traffic.

I-305 is least important for getting an interstate designation but its completely signed as only US-50 at the west end in Sacramento though.

[RobbieL2415]

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)

[Henry]

Top 5
I-405 CA
I-495 DC
I-495 NY
I-285 GA
I-110 CA

Bottom 5
I-180 WY
I-180 IL
I-895 NY
I-585 SC
I-375 MI