Interstate 12

[broadhurst04]

Why is Interstate 12 numbered as such? Shouldn't it be numbered as I-x10? It appears to exist solely as a northern bypass of New Orleans. Why does it have a mainline number when both termini lie on I-10 (85 miles apart) and there are no major cities along the way?

[NE2]

Because all intercity routes were numbered before any auxiliaries. So I-195 in RI and MA was I-95E, I-380 in PA was I-81E, etc.

[SP Cook]

Really, I-12 should be I-10 and I-10 should be the auxiliary.

[froggie]

Other way around, SP.  Longstanding numbering policy is for the 2-digit route to go through the city and the 3-digit route to bypass it.

[NE2]

The real reason that I-12 was never considered for part of I-10 is that early plans had it junctioning I-59 in Mississippi, north of I-10.
http://commons.wikimedia.org/wiki/File:Interstate_Highway_plan_June_27,_1958.jpg

[Quillz]

Other way around, SP.  Longstanding numbering policy is for the 2-digit route to go through the city and the 3-digit route to bypass it.

But don't Interstates also take the shortest path possible? I thought that was the reason why certain alignments don't necessarily always pass through or by major cities. In that case, it seems like I-10 would have had a more direct path through Louisiana by bypassing New Orleans.

But maybe that's never been the policy, I don't know for sure.

[Alps]

Other way around, SP.  Longstanding numbering policy is for the 2-digit route to go through the city and the 3-digit route to bypass it.

That's been broken before. See I-5W/E in California, where I-5W was broken up despite going through "the city" (Oakland).

[froggie]

It's been broken elsewhere (mainly in NC).  But those are exceptions rather than the rule.

[mgk920]

It's been broken elsewhere (mainly in NC).  But those are exceptions rather than the rule.

Also, I-90 vs. I-490 in the Rochester, NY area.

Mike

[berberry]

But don't Interstates also take the shortest path possible? I thought that was the reason why certain alignments don't necessarily always pass through or by major cities. In that case, it seems like I-10 would have had a more direct path through Louisiana by bypassing New Orleans.

But maybe that's never been the policy, I don't know for sure.

I don't know either, but if so there's yet another exeption right inside New Orleans itself - the I-610 is a shorter route across town than I-10.

[UptownRoadGeek]

I don't know either, but if so there's yet another exeption right inside New Orleans itself - the I-610 is a shorter route across town than I-10.

It's shorter, but the 610 still effectively bypasses the CBD.

[Alps]

It's been broken elsewhere (mainly in NC).  But those are exceptions rather than the rule.

Also, I-90 vs. I-490 in the Rochester, NY area.

Mike

That's a case of keeping I-90 on the Thruway rather than hopping on and off. I don't think the Turnpike systems are a fair comparison to the general principle.

[NE2]

I-80 around Chicago is almost the New Orleans situation rotated 180°, in that I-59 could have gone into New Orleans like I-55 into Chicago. The only major difference is that I-12 was a late addition (ca. 1957) and was not always planned to tie into I-10 at its east end.

[Brandon]

I-80 around Chicago is almost the New Orleans situation rotated 180°, in that I-59 could have gone into New Orleans like I-55 into Chicago. The only major difference is that I-12 was a late addition (ca. 1957) and was not always planned to tie into I-10 at its east end.

I-80 is meant to go to Joliet and Davenport.  I-90 and I-94 are meant to go to Chicago and north.

[NE2]

I-80 around Chicago is almost the New Orleans situation rotated 180°, in that I-59 could have gone into New Orleans like I-55 into Chicago. The only major difference is that I-12 was a late addition (ca. 1957) and was not always planned to tie into I-10 at its east end.

I-80 is meant to go to Joliet and Davenport.  I-90 and I-94 are meant to go to Chicago and north.

Just like I-10 could have been intended to go to Slidell and Mobile, with I-whatever splitting off at Baton Rouge to go to New Orleans (and south).

[UptownRoadGeek]

Well I-10 wasn't originally meant to pass through Slidell, what is now I-10 from N.O. to Slidell was supposed to be I-59. I-10 would have continued due east out of N.O. across the Rigolets toward Waveland. I-12 on the other hand would have gone up into Mississippi.

[Hot Rod Hootenanny]

Well I-10 wasn't originally meant to pass through Slidell, what is now I-10 from N.O. to Slidell was supposed to be I-59. I-10 would have continued due east out of N.O. across the Rigolets toward Waveland. I-12 on the other hand would have gone up into Mississippi.

That goes back to the "interstate" following US 61 into New Orleans and following US 90 out of New Orleans when the Interregional Highways plan was mapped out in the 1940s.

[lamsalfl]

I-12 carries the transcontinental traffic.  Good enough reason for me to give it a 2di.

[jwolfer]

I-12 carries the transcontinental traffic.  Good enough reason for me to give it a 2di.

I agree..Unlike I-97 in its present form

[US71]

Other way around, SP.  Longstanding numbering policy is for the 2-digit route to go through the city and the 3-digit route to bypass it.

But don't Interstates also take the shortest path possible? I thought that was the reason why certain alignments don't necessarily always pass through or by major cities. In that case, it seems like I-10 would have had a more direct path through Louisiana by bypassing New Orleans.

But maybe that's never been the policy, I don't know for sure.

I-40 in Arkansas dips to graze North Little Rock. If it took the shortest path, it would pass through Beebe. Maybe it was decided N.O. was significant enough to have major Interstate number such as 10 rather than 12 or a Spur/Loop of 10?

[NE2]

I-40 in Arkansas dips to graze North Little Rock. If it took the shortest path, it would pass through Beebe.

The main road has always followed the Arkansas River through Conway and Little Rock.

[US71]

I-40 in Arkansas dips to graze North Little Rock. If it took the shortest path, it would pass through Beebe.

The main road has always followed the Arkansas River through Conway and Little Rock.

And your point?

[NE2]

And your point in asking what my point is? Chill, bro.

[Alps]

I-40 in Arkansas dips to graze North Little Rock. If it took the shortest path, it would pass through Beebe.

The main road has always followed the Arkansas River through Conway and Little Rock.

And your point?

Read your own post. You asked why the Interstate doesn't follow the shortest path. Sometimes, it's because it follows the main road.

[lamsalfl]

I-40 in Arkansas dips to graze North Little Rock. If it took the shortest path, it would pass through Beebe. Maybe it was decided N.O. was significant enough to have major Interstate number such as 10 rather than 12 or a Spur/Loop of 10?

The Port of New Orleans is a port located in New Orleans, Louisiana. It is the 1st in the United States based on volume of cargo handled, second-largest in the state after the Port of South Louisiana, and 13th largest in the U.S. based on value of cargo. It also has the longest wharf in the world, which is 2.01 miles (3.4 km) long and can accommodate 15 vessels at one time.  http://en.wikipedia.org/wiki/Port_of_new_orleans

I think there's the answer.