Highest speed limit on a 3di

[Roadgeekteen]

The only 75 zones I know of are I-135 and I-335 in Kansas. I think that I-530 is getting a bump to 75 to. Any others at 75 or even 80?

[sprjus4]

For Texas, I don't believe any 3dis are actually posted above 70 mph, though some HO/T lanes in the Dallas-Fort Worth metro may be 75 mph on at least one 3di.

The closest thing would be SH-130, which acts as a 3di bypass of I-35 thru Austin, though is not an interstate highway. That is posted at 85 mph on the southern half, and 80 mph on the northern half.

[Max Rockatansky]

I-505 has 70 MPH zones in California. 

[Roadgeekteen]

I-505 has 70 MPH zones in California.

A lot of 3dis have 70 zones. 75 zones are probably a lot rarer.

[Max Rockatansky]

I-505 has 70 MPH zones in California.

A lot of 3dis have 70 zones. 75 zones are probably a lot rarer.

Yes, you'd be hard pressed to find 70 MPH elsewhere on a 3D in California. 

[Roadgeekteen]

I-505 has 70 MPH zones in California.

A lot of 3dis have 70 zones. 75 zones are probably a lot rarer.

Yes, you'd be hard pressed to find 70 MPH elsewhere on a 3D in California.

I think that I-580 and I-205 have some, but I'm not sure.

[Flint1979]

I believe the most on I-275, I-375, I-475, I-675, I-194, I-196, I-296, I-496 and I-696 is 70 mph.

[Roadgeekteen]

Is I-680 75 in Nebraska?

[Flint1979]

Is I-680 75 in Nebraska?

I think it's 65.

[US 89]

Most of Utah’s I-215 is 70 mph, but that’s just because Utah posts reasonable speed limits on urban freeways that can handle them.

[Great Lakes Roads]

I-469 on the east side of Fort Wayne is signed at 70 mph for almost the whole length.

I-265 and I-865 is signed as 65 mph.

I-465... yeah, let's not talk about that interstate with the speed limit of 55...

[Eth]

Georgia doesn't go above 70 MPH anywhere, but that at least includes portions of I-185, I-475, I-575, and I-985.

[Roadgeekteen]

Is I-680 75 in Nebraska?

I think it's 65.

I-680 and I-29 multiplex. When does I-29 drop in speed limit?

[Pink Jazz]

I-295 in VA I think is 70 mph.

[sprjus4]

Is I-680 75 in Nebraska?

I think it's 65.

I-680 and I-29 multiplex. When does I-29 drop in speed limit?

That's in Iowa, not Nebraska.

Additionally, I-680 ends at the southern I-29 junction and no longer overlaps I-29. The piece from the northern I-29 junction to I-80 was renumbered as I-880.

[sprjus4]

I-295 in VA I think is 70 mph.

70 mph throughout except a drop to 65 mph near the northern I-95 interchange.

[Max Rockatansky]

I-505 has 70 MPH zones in California.

A lot of 3dis have 70 zones. 75 zones are probably a lot rarer.

Yes, you'd be hard pressed to find 70 MPH elsewhere on a 3D in California.

I think that I-580 and I-205 have some, but I'm not sure.

580 does between 5 and 205.  I didn't take pictures of any speed limit signs for 205 but it sounds right. 

[Roadgeekteen]

Is I-680 75 in Nebraska?

I think it's 65.

I-680 and I-29 multiplex. When does I-29 drop in speed limit?

That's in Iowa, not Nebraska.

Additionally, I-680 ends at the southern I-29 junction and no longer overlaps I-29. The piece from the northern I-29 junction to I-80 was renumbered as I-880.

Oh snap how did I not know that.

[Life in Paradise]

I-465... yeah, let's not talk about that interstate with the speed limit of 55...

That is simply a suggestion.  If you want to live, you will be driving 5-10+ MPH over.

[sprjus4]

Is I-680 75 in Nebraska?

I think it's 65.

I-680 and I-29 multiplex. When does I-29 drop in speed limit?

That's in Iowa, not Nebraska.

Additionally, I-680 ends at the southern I-29 junction and no longer overlaps I-29. The piece from the northern I-29 junction to I-80 was renumbered as I-880.

Oh snap how did I not know that.

It used to be that way, it was changed in September 2019.

[sprjus4]

For North Carolina, the maximum speed limit on interstate highways is 70 mph. A few 3di highways, including in urban areas, are posted up to 70 mph. The rest are posted at 65 mph.

I-540 - Entire length around Raleigh
I-485 - Entire length around Charlotte
I-140 - Entire length around Wilmington

Future I-587 between Zebulon and Greenville will be posted at 70 mph for its entire length. The current freeway is entirely 70 mph though is not up to interstate standards not currently designated.

Most other 3di are posted at 65 mph.

[Flint1979]

Is I-680 75 in Nebraska?

I think it's 65.

I-680 and I-29 multiplex. When does I-29 drop in speed limit?

Not anymore. The part of 680 east of 29 is now I-880. I-29 stays in Iowa and to my knowledge Iowa's highest speed limit is 70.

[Revive 755]

Posted at 70 in Illinois
* I-155
* I-172
* I-180 (as previously mentioned)
* I-280 (yet drops to 65 in Iowa)
* I-355 from I-80 to around I-55
* I-474

The first three would probably go up to 75 if Illinois does increase the maximum speed limit.

Posted at 70 in Missouri
* I-155
* I-229 outside of the downtown stretch (posted at 55)
* I-435:  Sections posted at 70 on the north side?

[michravera]

I-505 has 70 MPH zones in California.

A lot of 3dis have 70 zones. 75 zones are probably a lot rarer.

Yes, you'd be hard pressed to find 70 MPH elsewhere on a 3D in California.

I think that I-580 and I-205 have some, but I'm not sure.

Both do in San Joaquin County. The I-580 part is much longer than the I-205 portion (since they dropped it to 65MPH through Tracy). I-580 basically misses Tracy, so keeps 70 MPH just about to the I-205 junction.
I am not sure about I-215 in California, but I thought so.

I am pretty sure that I-580 in Nevada is posted 70 MPH between Reno and Carson City and north of Reno. I am not sure when the I-580 designation stops and US-395 takes over.

Do any of the 80 MPH states have any 3dis to speak of? If I remember my maps correctly, their 3dis tend to be fairly near cities and would therefore be unlikely to be posted higher than 70MPH.

[sprjus4]

Do any of the 80 MPH states have any 3dis to speak of? If I remember my maps correctly, their 3dis tend to be fairly near cities and would therefore be unlikely to be posted higher than 70MPH.

Closest would be the 80 mph and 85 mph segments of SH-130 that serve as a 3di bypass of I-35 near Austin, TX, though it's not actually an interstate highway. I don't believe any actually are posted above 75 mph elsewhere in the country.