Long concurrencies vs. separate numbers -- discuss

[hbelkins]

I can see the need for the long I-80/I-90 concurrency, since x0 interstates are intended to be main cross-country highways.

What about others? I-20/I-59, for example? Why a concurrency instead of two numbers? I can easily see an I-53 for the southern portion, a solo I-20 between Meridian and Birmingham, then I-59 from Birmingham to Chattanooga.

Feel free to add your own example and thoughts.

[webny99]

The longest in my immediate area is US 20 and NY 5, which, though lengthy, is acceptable, since in the grand scheme of things, they are separate for far more miles than they are concurrent. With the exceptions of Livingston and Ontario counties, they also serve entirely different corridors.

Me personally, I don't really like long concurrencies. Although they do make sense in certain instances, I usually prefer just to leave the more important route number as the sole designation. Using too many numbers is not only a waste of resources, creating excessive signage and such, it also can cause confusion when there need be none, such as the thruway interchange in Utica. The more routes involved, the harder it becomes to interpret and act upon the message in a timely fashion 

[kphoger]

I am only in favor of short concurrencies, and even then only for major highways like Interstates and US Highways.  For state routes, I don't think there should be concurrencies longer than a mile or two.

I-90 should go from Seattle to Chicago and then terminate.
I-80 can stay San Francisco–New Jersey.
No concurrency between Chicago to Cleveland.
I-90 between Cleveland and Boston can become I-92.

[webny99]

I am only in favor of short concurrencies, and even then only for major highways like Interstates and US Highways.  For state routes, I don't think there should be concurrencies longer than a mile or two.

On this, we agree.

I-90 between Cleveland and Boston can become I-92.

Bad idea. In this case specifically, I would prefer the multiplex, or even having two separate I-90's, to I-92. Of course, my opinion is shaped by bias (not wanting to lose the I-X0 nearest me), but, personal beef aside, I still think there should be an I-X0 connecting Chicago and Boston.

[Brandon]

What about others? I-20/I-59, for example? Why a concurrency instead of two numbers? I can easily see an I-53 for the southern portion, a solo I-20 between Meridian and Birmingham, then I-59 from Birmingham to Chattanooga.

This goes a bit into fictional territory, but I think it's I-20 that could move on that one.  Had a Meridian to Montgomery freeway been built, I-20 should've used that with the current I-85 to Atlanta via Montgomery.  I-20 from Birmingham to Atlanta would then be an extension of I-22 (with this as the original I-22 section).

Another option would be I-59, New Orleans to Meridian, with an I-73 from Birmingham to Chattanooga.

As for my opinion on long concurrencies versus two separate routes, it depends on the routes, IMHO.  I'm not adverse to them though.

[Scott5114]

Usually, I prefer separate numbers if the concurrency is more than 5 to 10 miles or so. There are some cases, like two overlapping corridors each connecting two important destinations, where a concurrency might still be preferable.

An obvious exception to this is in the cases where Interstates overlap a US route.

[bing101]

I-7 or I-9 from Sacramento to Grapevine is supposed to be concurrent with CA-99.

[Bitmapped]

I generally prefer concurrencies to be short (under 5-10 miles) unless the concurrency is needed to keep the same number for a long distance corridor. Some states, like West Virginia, seem to overuse concurrencies to conserve numbers. For example, WV 12 has two distinct N/S segments (WV 12/Hinton to Peterstown, Alderson to Alta) that are joined by a 16-mile concurrency with WV 3 (corrected). I'd eliminate the concurrency and renumber one of the sections.

I don't like having multiple disconnected segments with the same route number in the same state. Virginia does this with some routes like VA 42. I'd renumber the individual pieces in this case.

[webny99]

^ WV 12 has a 16 mile concurrency with itself?

[hotdogPi]

^ WV 12 has a 16 mile concurrency with itself?

According to Wikipedia, it should be with WV 3, not with itself.

[webny99]

^ WV 12 has a 16 mile concurrency with itself?

According to Wikipedia, it should be with WV 3, not with itself.

Google Maps (my default) agrees. I knew it didn't concur with itself, I just decided to note the typo in the form of a question. 

[Jim]

I don't like the I-80/I-90 concurrency but short of annexing southern Ontario and running I-90 across from the NF area to Windsor or Sarnia then having it take over I-94 or I-96 across Michigan, I think the current setup is a good solution.  I agree with HB that the I-20/I-59 lengthy concurrency isn't really necessary.

Most of the other interstate concurrencies I can think of are pretty short and don't bother me.  A couple exceptions are I-15/I-84, where the smallish east end of I-84 could survive perfectly well as an I-x15 or I-x80, and I-29/I-680, where I don't think it would be bad to have separate numbers for the parts of I-680 on either side.

Edit: one more I don't like is the I-35/I-80 when one of them could just as easily be routed on I-235, eliminating the need for that 3di altogether.

[hotdogPi]

I-73/74 should be fixed.

[HazMatt]

It depends, but it's hard to give definitive criteria as there will always be exceptions.  Short concurrencies are fine so we don't just waste numbers.  If it keeps a logical corridor intact, such as Chattanooga->New Orleans, I'm fine with it.  I-80/90 fits that mold, plus it has environmental constraints where it makes sense as well.  The I-39/90 concurrency strikes me as useless as I don't see much use for a Stevens Point->Bloomington corridor (just use I-43 for the southern portion).  Long US/state highway concurrencies are generally useless (US 15/501, NC 24/27) but again would depend on the specific instance.

[briantroutman]

I'm fine with concurrencies–even long ones–provided that the continuation of both routes serves to identify a logical corridor for a significant flow of traffic...and also provided that the concurrency doesn't present undue complication or confusion in signing.

For instance, let's look at I-70 and I-76 in Pennsylvania. And let's assume that I-70 takes priority being an X0 and a semi-transcontinental route. And for the sake of this discussion, we won't get into issues of discontinuity at Breezewood. Let's imagine that there are continuous high-speed connections between "free"  I-70 and the Turnpike on both ends.

So why not make Ohio to New Stanton I-76, New Stanton to Breezewood I-70 only, and Breezewood to NJ I-72 or I-74 (assuming that these numbers were still available)? Because even though St Louis/Indianapolis/Columbus to Baltimore/Washington is a significant, logical travel corridor, so too is Philadelphia to Pittsburgh, Pittsburgh to Cleveland–and ultimately by extension via I-80, Philadelphia to Chicago.

This logic is also why I don't support extending I-99 north of I-80: Considered in total (Corning to Bedford), it's just not a logical route, and it certainly doesn't merit incorporation into a highly visible Interstate designation over the other much more important interstate and international flows of traffic (Toronto to Baltimore/Washington, Buffalo to Baltimore/Washington, Rochester to Baltimore/Washington) that use the same corridor.

[Revive 755]

The only long concurrency that really bothers me at the moment is the I-94 with I-41 south of Milwaukee.

Now if there were greater signs of interstate development for a corridor parallel but south of the toll facilities in Indiana and Ohio, I might take more issue with the I-80/I-90 concurrency.  I might also take more issue with the I-20/I-59 overlap if there was movement/construction of a corridor from Meridian to Nashville.

IIRC one of the earlier interstate numbering plans  - think it may be lurking in one of the older threads - had the I-59/I75/I-81 corridor using the same number, and would have provided a chance for long concurrencies with I-75 and I-40.

[Hurricane Rex]

The only one that bothers me is OR 99/I 5. It can be divided into segments.

[hotdogPi]

For US routes:

Long overlaps in the middle of a route, like 6/34, 70/79, 6/50 (NV/UT line), and 19/98 are fine, and they don't need to change.

US 63 doesn't need to exist in Louisiana. It's completely overlapped with US 167.
US 400 should be truncated to where it isn't US 50 or US 54. (I would say the same thing about US 166, but truncating both ends would leave US 400 in a single state.)
Only one of US 69, 96, and 287 should go to Port Arthur, TX.
While not "long", US 270 doesn't need to be in Kansas.
US 62 doesn't need to be with US 180. (180 continues in both directions from the overlap, so it stays, while 62 would get removed.)
US 341 does not need to be with US 25.

I'm also not a fan of extremely long Interstate/US concurrencies. Move the US route back to the old road if possible.

[webny99]

One thing I noticed recently, in my road atlas, and Google Maps confirmed it, is that every single US route in Alabama is concurrent with an AL state route for it's entire length. Why is this? Seems to me like a waste of numbers and a bunch of extra confusion.

Having said that, I'm not sure if any of these "concurrencies" are signed as such, but would be interested in knowing which ones are co-signed (if any). The two places I checked at random on GMSV did not have signage posted for the state route.

I'm also not a fan of extremely long Interstate/US concurrencies. Move the US route back to the old road if possible.

Agreed. In most cases, the US route should be kept on the old alignment.

[hotdogPi]

One thing I noticed recently, in my road atlas, and Google Maps confirmed it, is that every single US route in Alabama is concurrent with an AL state route for it's entire length. Why is this? Seems to me like a waste of numbers and a bunch of extra confusion.

Having said that, I'm not sure if any of these "concurrencies" are signed as such, but would be interested in knowing which ones are co-signed (if any). The two places I checked at random on GMSV did not have signage posted for the state route.

They aren't signed in Alabama, but they are in Georgia.

[webny99]

One thing I noticed recently, in my road atlas, and Google Maps confirmed it, is that every single US route in Alabama is concurrent with an AL state route for it's entire length. Why is this? Seems to me like a waste of numbers and a bunch of extra confusion.

Having said that, I'm not sure if any of these "concurrencies" are signed as such, but would be interested in knowing which ones are co-signed (if any). The two places I checked at random on GMSV did not have signage posted for the state route.

They aren't signed in Alabama, but they are in Georgia.

Is this something that has been discussed elsewhere on the forum?
I had never heard of, or noticed, it before.

[hbelkins]

One thing I noticed recently, in my road atlas, and Google Maps confirmed it, is that every single US route in Alabama is concurrent with an AL state route for it's entire length. Why is this? Seems to me like a waste of numbers and a bunch of extra confusion.

Having said that, I'm not sure if any of these "concurrencies" are signed as such, but would be interested in knowing which ones are co-signed (if any). The two places I checked at random on GMSV did not have signage posted for the state route.

They aren't signed in Alabama, but they are in Georgia.

Actually, many of them ARE signed in Alabama.

[Eth]

US 341 does not need to be with US 25.

US 25 is completely redundant south of Statesboro. Just end it at US 80. There's a better way to get from Augusta to Brunswick anyway, via I-16 and I-95.

One thing I noticed recently, in my road atlas, and Google Maps confirmed it, is that every single US route in Alabama is concurrent with an AL state route for it's entire length. Why is this? Seems to me like a waste of numbers and a bunch of extra confusion.

Having said that, I'm not sure if any of these "concurrencies" are signed as such, but would be interested in knowing which ones are co-signed (if any). The two places I checked at random on GMSV did not have signage posted for the state route.

They aren't signed in Alabama, but they are in Georgia.

Is this something that has been discussed elsewhere on the forum?
I had never heard of, or noticed, it before.

Yeah, it comes up from time to time. Florida and Tennessee also do it, though Georgia's the only one that normally signs them (I've seen them on a couple occasions in Alabama and Florida, but I think those are contractor errors). Generally speaking, the state routes were there first and the US routes were just laid over top of them instead of replacing them.

[kphoger]

one more I don't like is the I-35/I-80 when one of them could just as easily be routed on I-235, eliminating the need for that 3di altogether.

I don't like the "bump" that 35 and 80 would have to do if you renumbered 235.  IMO, there shouldn't be an interstate junction where both through-routes change numbers to each other.

[froggie]

Is this something that has been discussed elsewhere on the forum?

It has, yes.  But I couldn't recall which threads offhand.  Do a search.

On the flip side of the premise of this thread, what about two routes that together form a longer single corridor, but are given two separate numbers instead?

One example that has been brought up in "roadgeek circles" in the past is I-59 and I-81.  Though it would require concurrencies with I-75 and I-40, it's been argued that this corridor should have been given a single number instead of being separated into I-59 and I-81.

Another one is US 72 and US 76.  They come VERY CLOSE (within a mile) of ending end-to-end in Chattanooga, and combined they would follow a similar east-west path in each direction from Chattanooga.