North Carolina

[SkyPesos]

I-340 would be a better fit for this corridor. Why that number wasn't used before I-540 or even I-140 is puzzling to me.

340 is one of those 3di numbers that I'm sort of surprised haven't been used yet. Same with 570, and fun fact: I-70 is the only x0 2di without a 5xx 3di, and one of two x0 and x5 (along with I-25) that doesn't have a 5xx.

[sprjus4]

^ I-545 doesn't exist either.

[tolbs17]

I wonder which corridor that isn't yet planned to become an Interstate corridor might become one in the future? Perhaps the US 421 corridor between Wilkesboro and Winston-Salem will be proposed as an Interstate 46?

If anything, make that a I-x77 instead.  Way too short for a 2di IMO.

I'd argue it doesn't even need a designation. It doesn't really connect any major population centers to warrant one. Perhaps a 3di if desired, however. The US-421 freeway would need upgrading, given its age in many areas.

I-340 would be a better fit for this corridor. Why that number wasn't used before I-540 or even I-140 is puzzling to me.

Can't I-540 just be renumbed to I-640 already?

[sprjus4]

I wonder which corridor that isn't yet planned to become an Interstate corridor might become one in the future? Perhaps the US 421 corridor between Wilkesboro and Winston-Salem will be proposed as an Interstate 46?

If anything, make that a I-x77 instead.  Way too short for a 2di IMO.

I'd argue it doesn't even need a designation. It doesn't really connect any major population centers to warrant one. Perhaps a 3di if desired, however. The US-421 freeway would need upgrading, given its age in many areas.

I-340 would be a better fit for this corridor. Why that number wasn't used before I-540 or even I-140 is puzzling to me.

Can't I-540 just be renumbed to I-640 already?

It's never going to happen, for a number of reasons. It frankly, doesn't need to be.

[SkyPesos]

Honestly, screw the entire first digit rule for 3dis, it's already inconsistent enough with today's examples. Unlike with the odd-even rule for 2dis, bet a good portion of the the public probably don't know about the 3dis rule..

[tolbs17]

^

They may be old, but given low traffic volumes, they are likely in adequate shape. As Mapmikey mentioned above, they would've been replaced otherwise apart of the I-85 reconstruction.

The mainline bridges were replaced in that project (much heavier traffic, obviously) not crossing roads though.

https://www.google.com/maps/@35.4412691,-80.626392,3a,75y,70.85h,95.38t/data=!3m7!1e1!3m5!1sDmrByjcVTEObAtudYOM05w!2e0!5s20190901T000000!7i16384!8i8192!5m1!1e1

Here too!

[wdcrft63]

I wonder which corridor that isn't yet planned to become an Interstate corridor might become one in the future? Perhaps the US 421 corridor between Wilkesboro and Winston-Salem will be proposed as an Interstate 46?

If anything, make that a I-x77 instead.  Way too short for a 2di IMO.

I'd argue it doesn't even need a designation. It doesn't really connect any major population centers to warrant one. Perhaps a 3di if desired, however. The US-421 freeway would need upgrading, given its age in many areas.

I-340 would be a better fit for this corridor. Why that number wasn't used before I-540 or even I-140 is puzzling to me.

Can't I-540 just be renumbed to I-640 already?

It's never going to happen, for a number of reasons. It frankly, doesn't need to be.

This question comes up (understandably) in the Forum from time to time. Briefly: when the northern arc of the loop was designed NCDOT asked for the 640 designation. The Feds would not approve that because the northern arc didn't end at an interstate (now it does: I-87). So they insisted on 540. After a decade or two of everyone in the area calling the road 540 NCDOT doesn't see any good reason to change the number just to satisfy road geeks like us.

[SkyPesos]

This question comes up (understandably) in the Forum from time to time. Briefly: when the northern arc of the loop was designed NCDOT asked for the 640 designation. The Feds would not approve that because the northern arc didn't end at an interstate (now it does: I-87). So they insisted on 540. After a decade or two of everyone in the area calling the road 540 NCDOT doesn't see any good reason to change the number just to satisfy road geeks like us.

Sounds like AASHTO was being picky in the exact opposite way as the St Louis beltway numbering. Back when that was getting its number, and only the western section was built, MoDOT wanted I-144, but AASHTO gave I-244 instead (now I-270) because they knew that it'll eventually become a (partial) beltway. I'm not sure if NCDOT had plans to extend I-540 into a beltway back then, but if they had, I have no clue why AASHTO rejected the I-640 number knowing about those plans.

My own guess with 540 over 640 is that 640 would get confused with US 64 in the area. Not sure how true it is, but it works for me.

[The Ghostbuster]

Also since only the portion of 540 from Interstate 40 (West Junction) to Interstate 87 over the northern half of the beltway will be an Interstate (the rest, of course, will be NC 540), maybe an odd first digit was appropriate after all. However, I still agree that 540 should have been Interstate/NC 640 to begin with; the 540 designation should have been saved for another corridor, such as the US 1 corridor southwest of Raleigh, or the Wade Avenue Freeway corridor. Of course that is assuming either corridor would be approved as Interstates to begin with.

[Dirt Roads]

This question comes up (understandably) in the Forum from time to time. Briefly: when the northern arc of the loop was designed NCDOT asked for the 640 designation. The Feds would not approve that because the northern arc didn't end at an interstate (now it does: I-87). So they insisted on 540. After a decade or two of everyone in the area calling the road 540 NCDOT doesn't see any good reason to change the number just to satisfy road geeks like us.

Sounds like AASHTO was being picky in the exact opposite way as the St Louis beltway numbering. Back when that was getting its number, and only the western section was built, MoDOT wanted I-144, but AASHTO gave I-244 instead (now I-270) because they knew that it'll eventually become a (partial) beltway. I'm not sure if NCDOT had plans to extend I-540 into a beltway back then, but if they had, I have no clue why AASHTO rejected the I-640 number knowing about those plans.

My own guess with 540 over 640 is that 640 would get confused with US 64 in the area. Not sure how true it is, but it works for me.

Also, hardly anybody ever expected the explosion in the local population.  The 1990 U.S. Census pegged Raleigh at 220K and Wake at 426K.  The 2020 Estimate show Raleigh at 474K and Wake at just over 1.1M.  During the same time, North Carolina went from just under 1.9M to 10.6M.  In the process, our clout with the other states at AASHTO has increased significantly.

[architect77]

I wonder which corridor that isn't yet planned to become an Interstate corridor might become one in the future? Perhaps the US 421 corridor between Wilkesboro and Winston-Salem will be proposed as an Interstate 46?

If anything, make that a I-x77 instead.  Way too short for a 2di IMO.

I'd argue it doesn't even need a designation. It doesn't really connect any major population centers to warrant one. Perhaps a 3di if desired, however. The US-421 freeway would need upgrading, given its age in many areas.

I-340 would be a better fit for this corridor. Why that number wasn't used before I-540 or even I-140 is puzzling to me.

Can't I-540 just be renumbed to I-640 already?

It's never going to happen, for a number of reasons. It frankly, doesn't need to be.

I think for simplicity it will be, especially after 540's bonds are paid off.

NC once got permission to toll I-95 and in the interest of public safety and understanding I predict the complete loop will have one name and hopefully I-640.

Remember Wake Forest Rd in Raleigh got renamed, used to be OLD WAKE FOREST RD. and Capital Blvd. used to be just NORTH BLVD.

[architect77]

I wonder which corridor that isn't yet planned to become an Interstate corridor might become one in the future? Perhaps the US 421 corridor between Wilkesboro and Winston-Salem will be proposed as an Interstate 46?

If anything, make that a I-x77 instead.  Way too short for a 2di IMO.

I'd argue it doesn't even need a designation. It doesn't really connect any major population centers to warrant one. Perhaps a 3di if desired, however. The US-421 freeway would need upgrading, given its age in many areas.

I-340 would be a better fit for this corridor. Why that number wasn't used before I-540 or even I-140 is puzzling to me.

Can't I-540 just be renumbed to I-640 already?

It's never going to happen, for a number of reasons. It frankly, doesn't need to be.

This question comes up (understandably) in the Forum from time to time. Briefly: when the northern arc of the loop was designed NCDOT asked for the 640 designation. The Feds would not approve that because the northern arc didn't end at an interstate (now it does: I-87). So they insisted on 540. After a decade or two of everyone in the area calling the road 540 NCDOT doesn't see any good reason to change the number just to satisfy road geeks like us.

But that's not the problem.

I-540 and NC540 being one loop isn't clear to the public who rely on the red white and blue quite a lot.

I wouldn't care if the completed loop was I-540 because I'll bet over 90% of the public doesn't think about or even know that even and odd first numbers indicate different capabilities or end destinations of interstates.

Hell even DOTs like in Ohio will sign a road using different shields ( state, US, county) on a single numbered route through the state.

However I think red, white and blue with one number for a full loop is essential in conveying its loop capabilities to the public which is why we build loops at all  to connect to every other road around a city.

[Strider]

I wonder which corridor that isn't yet planned to become an Interstate corridor might become one in the future? Perhaps the US 421 corridor between Wilkesboro and Winston-Salem will be proposed as an Interstate 46?

If anything, make that a I-x77 instead.  Way too short for a 2di IMO.

I'd argue it doesn't even need a designation. It doesn't really connect any major population centers to warrant one. Perhaps a 3di if desired, however. The US-421 freeway would need upgrading, given its age in many areas.

I-340 would be a better fit for this corridor. Why that number wasn't used before I-540 or even I-140 is puzzling to me.

Can't I-540 just be renumbed to I-640 already?

It's never going to happen, for a number of reasons. It frankly, doesn't need to be.

I think for simplicity it will be, especially after 540's bonds are paid off.

NC once got permission to toll I-95 and in the interest of public safety and understanding I predict the complete loop will have one name and hopefully I-640.

Remember Wake Forest Rd in Raleigh got renamed, used to be OLD WAKE FOREST RD. and Capital Blvd. used to be just NORTH BLVD.

There are no plans to change from 540 to I-640, even after the bonds are paid off, or else it would have been already mentioned. So, the loop is going to stay I-540/NC540.

[Roadsguy]

I wonder which corridor that isn't yet planned to become an Interstate corridor might become one in the future? Perhaps the US 421 corridor between Wilkesboro and Winston-Salem will be proposed as an Interstate 46?

If anything, make that a I-x77 instead.  Way too short for a 2di IMO.

I'd argue it doesn't even need a designation. It doesn't really connect any major population centers to warrant one. Perhaps a 3di if desired, however. The US-421 freeway would need upgrading, given its age in many areas.

I-340 would be a better fit for this corridor. Why that number wasn't used before I-540 or even I-140 is puzzling to me.

Can't I-540 just be renumbed to I-640 already?

It's never going to happen, for a number of reasons. It frankly, doesn't need to be.

I think for simplicity it will be, especially after 540's bonds are paid off.

NC once got permission to toll I-95 and in the interest of public safety and understanding I predict the complete loop will have one name and hopefully I-640.

Remember Wake Forest Rd in Raleigh got renamed, used to be OLD WAKE FOREST RD. and Capital Blvd. used to be just NORTH BLVD.

There are no plans to change from 540 to I-640, even after the bonds are paid off, or else it would have been already mentioned. So, the loop is going to stay I-540/NC540.

I say once the bonds are paid off, they should apply to make the entire thing I-540. If that gets rejected, they should just pull an MD 695 and sign it I-540 anyway.

[tolbs17]

I was thinking the rules are the odd numbers are for spurs and the even numbers are for bypasses (and business routes) and beltways.

[sprjus4]

I was thinking the rules are the odd numbers are for spurs and the even numbers are for bypasses (and business routes) and beltways.

Those are the general rules, but there's obviously many exceptions. I-540 / NC-540 is one of them. Also look at I-520. It's not a new thing.

[tolbs17]

I was thinking the rules are the odd numbers are for spurs and the even numbers are for bypasses (and business routes) and beltways.

Those are the general rules, but there's obviously many exceptions. I-540 / NC-540 is one of them. Also look at I-520. It's not a new thing.

Non-roadgeeks wouldn't care.

[roadman65]

I -526 in SC. It seems SC does it twice.

I-376 recently came into fame in PA as it was originally a spur. Now extended over I-279, US 22& 30, and PA 60.

[wdcrft63]

I -526 in SC. It seems SC does it twice.

I-376 recently came into fame in PA as it was originally a spur. Now extended over I-279, US 22& 30, and PA 60.

I-376 is almost 85 miles long. Somebody in the Forum knows: what is the longest 3di?

[kevinb1994]

I -526 in SC. It seems SC does it twice.

I-376 recently came into fame in PA as it was originally a spur. Now extended over I-279, US 22& 30, and PA 60.

I-376 is almost 85 miles long. Somebody in the Forum knows: what is the longest 3di?

I-476! Whenever I-369 in Texas is finished though, that one will beat it. I have read that there was a period where I-495 in Massachusetts was the longest.

[Dirt Roads]

I -526 in SC. It seems SC does it twice.

Not quite.  I-526 may be a bypass of Charleston, but it is a double spur of its parent I-26.  I presume that I-140 around Wilmington will eventually do the same thing.

[tolbs17]

I -526 in SC. It seems SC does it twice.

Not quite.  I-526 may be a bypass of Charleston, but it is a double spur of its parent I-26.  I presume that I-140 around Wilmington will eventually do the same thing.

So, where will I-640 go?

[SkyPesos]

I -526 in SC. It seems SC does it twice.

Not quite.  I-526 may be a bypass of Charleston, but it is a double spur of its parent I-26.  I presume that I-140 around Wilmington will eventually do the same thing.

So, where will I-640 go?

Knoxville

[sprjus4]

I -526 in SC. It seems SC does it twice.

Not quite.  I-526 may be a bypass of Charleston, but it is a double spur of its parent I-26.  I presume that I-140 around Wilmington will eventually do the same thing.

I-140 only connects to I-40 in one place. I-40 ends just south of I-140.

[ahj2000]

I -526 in SC. It seems SC does it twice.

I-376 recently came into fame in PA as it was originally a spur. Now extended over I-279, US 22& 30, and PA 60.

I-376 is almost 85 miles long. Somebody in the Forum knows: what is the longest 3di?

I-476! Whenever I-369 in Texas is finished though, that one will beat it. I have read that there was a period where I-495 in Massachusetts was the longest.

I don't have the exact miles, but I think 476 will still take the cake. Barely. A quick google map rn says Texarkana to Tenaha is 115 mi following US 59 as opposed to I 476's 132.1 mi length. 476 is both a partial suburban belt thing and a ridiculously long spur to Scranton, so it's a touch longer than it even seems it is.