Should Route Number Duplication be Used by a Given State?

[Rover_0]

What I mean by route number duplication (RND) is that a state numbers its state highways the same number as a US or Interstate route within its borders.  Utah does not do this; instead, UDOT has a "one route, one number" policy--there is no UT-15, UT-80, UT-70, UT-89, UT-6, etc. as there are Interstates and US Routes that have these numbers.

In some apparent cases, the state may just seem to have too many routes (Texas), but do you think it's a good idea?  I think not using it for Utah works, as people refer to a given route as "highway ##" and the state isn't exactly packed with roads, though that's a bit of a nutshell answer.

[US71]

What I mean by route number duplication (RND) is that a state numbers its state highways the same number as a US or Interstate route within its borders.  Utah does not do this; instead, UDOT has a "one route, one number" policy--there is no UT-15, UT-80, UT-70, UT-89, UT-6, etc. as there are Interstates and US Routes that have these numbers.

I think the MUTCD discourages duplication, but Missouri duplicates 64, 72 , 170 and 49.

Arkansas has NO duplicates (for now... until I-49 gets officially posted)

If the state route is far enough away from the Interstate or US Route, I see no problem.

For the longest time, though, I was confused by 2 Hwy 59's within a few miles of each other (AR 59 in Siloam Springs, US 59 in Oklahoma).

[WillWeaverRVA]

California is a good example of a state that does not permit such duplications, although there are several exceptions - CA 15, CA 110, I-238 etc.

[roadfro]

I think duplication of route numbers should be avoided in all states. In a highway system based on numbered routes, duplicating a number for two unrelated highways can cause confusion to drivers. This is especially troublesome to those drivers unfamiliar with an area, or in region where highways are referred to as "route X" or "highway X" regardless of classification.  An understandable exception to this viewpoint comes in certain cases (such as I-15/CA SR 15 in San Diego or I-215/Clark CR 215 in Las Vegas) where the route numbers are used to denote a single highway facility and the classification changes solely due to ownership/maintenance/future Interstate status.

It should be worth noting that the original Interstate Highway grid was designed to mirror the numbering methods of the U.S. Highway system, yet was done in such a way that Interstates would not duplicate the number of any U.S. Route within a state.

[xonhulu]

I also see no problem with route duplication, if the roads are far enough apart. 

Oregon has two of these:  I-205/OR 205, which are nowhere near each other, and I-82/OR 82, which unfortunately are close enough to potentially cause confusion.

[agentsteel53]

For the longest time, though, I was confused by 2 Hwy 59's within a few miles of each other (AR 59 in Siloam Springs, US 59 in Oklahoma).

isn't AR-59 an old US-59 alignment?

[74/171FAN]

I definitely don't agree with that especially because in Virginia the only duplicate route number(not including state highway extensions of US Routes or interstates) is 13 but US 13 is over in Hampton Roads and the Eastern Shore while VA 13 exists near US 60 in Powhatan and Cumberland Counties over 100 miles west.

[Duke87]

Bad idea, unless the two routes are continuous with each other (e.g. I-390/NY 390).

Actually, it's probably best that even three digit numbers that could potentially be spurs of an interstate within the state be avoided unless they have some relation to the interstate. For instance, VA 895 is okay since it does meet I-95 even if it isn't officially a spur of it. But routes like CT 195 (exists in the same state as I-95 but is completely unrelated to it) are probably less than ideally numbered.
This is also good because it means CA 180 has to get axed, making the number available for you-know-what.

[corco]

No, for the simple reason that I store routes by route number on my FTP server and when there's duplication (eg I-82/OR 82, US-14/WYO 14, US-30/WYO 30, US-310/WYO 310, US-212/WYO 212, US-89/WYO 89, etc), it becomes annoying.

In seriousness, for the most part I frown upon it, but I find anomalies like WYO 89 where it's signed as such just because Wyoming was pissed off that Idaho and Utah got US-89 to be hilarious.

Really, it would be easily avoided if states would just inventory their routes by highway number instead of some random control number (without prefix), like Washington or California does...in Wyoming US-212 is ML 38 and ML 488, and WYO 212 is ML 212. Oregon does the same thing except even more annoyingly.

[Revive 755]

I think it depends upon the length of the routes in question, the types of routes, and the proximity of said routes.  In Illinois, there doesn't seem to be any problems with having I-24 and US 24 in the same state.  

In Missouri, the letter routes are duplicated many times, yet this only becomes a problem when two routes with the same letter suggest a route that is continuous yet is not - such as the two Rte T's near St. Joesph, one in Holt County, the other in Andrew County, which are separated by a narrow gravel road in a continuous corridor.  The other problematic case is when two routes with the same letter are very close to each other.  There are two Rte F's, one in Andrew County, the other in Dekalb County within five miles of each other that both run north-south.

Then there's the somewhat annoying Nebraska cases, such as with NE 103, which has two separate sections that someone never bothered to connect.  This one is wrong because a causal motorist (one who is not seriously planning their trip with detail studies of maps) can come across NE 103 on NE 8 and make the incorrect assumption that the route can be followed north to I-80 easily.

As for duplicating three digit interstate numbers, I don't see how having an I-470 in Missouri around Kansas City and possibly having another one in the St. Louis area (say changing MO 370 to another I-470) would be any worse for the general public than the proximity of the Kansas City I-470 to the Topeka I-470.  Only people who might really have a problem with this are the Feds and those in MoDOT's central office who might have to process data and distinguish between the two.    

[PAHighways]

Cosmetically there appears to be several duplicates in Pennsylvania, but technically there are none.

[Hellfighter]

Michigan has that unfortunately policy, Southern US-10 is now M-10, old US-27 is M-27, and old US-25 is now M-25. Also there's M-24 and a US-24 nearly on the same route.

[myosh_tino]

California is a good example of a state that does not permit such duplications, although there are several exceptions - CA 15, CA 110, I-238 etc.

Technically, these aren't duplications.  CA-15 and CA-110 are extensions of I-15 and I-110 where the freeway does not meet interstate standards.  CA-15 will eventually become I-15 once improvements are made.  CA-110 will never get upgraded to interstate standards because of the historic nature of the road.  I-238 was originally the freeway extension of CA-238 between I-580 and I-880 so technically it falls under the same classification as CA-15 and CA-110.

[Bickendan]

If you want to get technical about CA/I-110, there are two CA 110s, but both are extensions of I-110. The southern portion isn't freeway, though.

[english si]

It should be worth noting that the original Interstate Highway grid was designed to mirror the numbering methods of the U.S. Highway system, yet was done in such a way that Interstates would not duplicate the number of any U.S. Route within a state.

Other than in the middle - hence the lack of E-W numbers between I-44 and I-64.

Being English, I don't have a problem with it - it's not that confusing - we have it all the time - some things like the A23 being bypassed by the M23, other things like the M11, where it bypasses the A11 for a bit then goes elsewhere. The M57 and A57 are perpendicular too each other, which while less good, doesn't cause a problem. In part this is because we navigate by place a lot more (though not as much as mainland Europe), and also it's the case that we've learnt to cope.

I also fail to see how this duplication thing is such an issue, when there's business routes, various suffixes (E, W, N, S, A), spurs (eg I-270 Spur), bypass routes and so on, prevalent across the country - not in every state, but in a lot.

[J N Winkler]

I am not fussed either way, but it is certainly true that if a state permits duplicates, they have to be treated in a way which is user-friendly to motorists who don't pay much attention to system classification.  For instance, Texas has interchanges with both SH 121 and FM 121 on US 75 north of Dallas, and drivers passing the FM 121 exit have to be warned not to exit there for DFW Airport.

[SSOWorld]

I-238 was originally the freeway extension of CA-238 between I-580 and I-880 so technically it falls under the same classification as CA-15 and CA-110.

Originally? You mean it's being renamed CA-238? 

WI has two duplicates.

*I-39 was put in place with a WIS-39 already in place, but the latter is 50 miles west of the former.  WIS-794 is an extension of I-794 over a parkway that was originally to be a freeway but fell to NIMBYism.  Wisconsin otherwise despises duplication.

[algorerhythms]

MD has a rather blatant example: the exits for I-68 and MD 68 on I-70 are only about ten miles apart. The State Highway Administration installed signs on I-70 at the MD 68 exit to warn drivers that it's not the exit for I-68. I suppose that was less expensive than renumbering MD 68 when I-68 received its number.

[Brandon]

I see no problem what-so-ever with route number duplication.  There is a distinct differenct between I-24 and US-24, between I-72 and Illinois 72, between I-96 and M-96.  Route duplication seems to promote awareness that there are different route (I, US, state, etc).  In states that don't duplicate, everything is simply a highway (Highway 94, Highway 141, and Highway 16) with no difference made between types of routes.  People tend to get sloppier IMHO.  I've also noticed fewer shield mistakes in the Midwestern states that duplicate (IDOT, InDOT, MDOT) over those that don't (yeah, WisDOT, I'm looking at you!).

[US71]

For the longest time, though, I was confused by 2 Hwy 59's within a few miles of each other (AR 59 in Siloam Springs, US 59 in Oklahoma).

isn't AR-59 an old US-59 alignment?

Sort of. It appears to have been TEMP US 59 while modern-day US 59 was being built.  Maps are somewhat vague and AHTD isn't very knowledgeable about highway history (I asked them once when they changed from State ## Road to Arkansas ## and was told they quit using cut-outs in 1971).

[hbelkins]

MD has a rather blatant example: the exits for I-68 and MD 68 on I-70 are only about ten miles apart. The State Highway Administration installed signs on I-70 at the MD 68 exit to warn drivers that it's not the exit for I-68. I suppose that was less expensive than renumbering MD 68 when I-68 received its number.

And then you have Indiana, where I-64 actually has an interchange with IND 64 and the two routes parallel each other heading westward from the Louisville metro area.

[Rover_0]

I think that one of the few exceptions is to use state numbers as an alternative (i.e., Business, Alternate, Truck Routes, etc.) to Interstate and U.S. Highways.  Of course, that's why we have bannered US routes and Interstate business loops.  AASHTO could be leaning toward this approach in the future.

Good Utah US dup. examples could be a UT-6 running along what is now UT-198 as a city/surface alternative to the I-15/US-6 freeway in Utah County, a UT-89 along current UT-118 from Sevier to Salina with the same purpose, or a UT-91 along UT-252 in the Logan area (as that is a bypass for truckers on US-91 that want to avoid downtown Logan, aka Stoplight Hell).  This could also be a good option for Interstate Business routes; all of I-15's business routes could be UT-15, I-70's UT-70, and so on.  However, people may still get confused.

Number duplication was, in my opinion, one of the reasons why the 3-mile stretch of US-89A in Utah was signed (and defined) as UT-11 for so long.  Now UDOT just needs to sign it (which they should be doing soon).

[mefailenglish]

MD has a rather blatant example: the exits for I-68 and MD 68 on I-70 are only about ten miles apart. The State Highway Administration installed signs on I-70 at the MD 68 exit to warn drivers that it's not the exit for I-68. I suppose that was less expensive than renumbering MD 68 when I-68 received its number.

Maryland has a few others:  MD 70 and I-70; MD 97 and I-97; MD 270 and I-270; MD 495 and I-495.  There used to be a MD 95 but I think it's been decommissioned.  There is a MD 170, but I-170 of course is long gone.

[TheStranger]

Revive 755: I know Quebec does that with Autoroute 440, using it twice...

Bickendan: I think the southern State Route 110 has been decomissioned in recent years, I've never been to San Pedro though.

[Roadgeek Adam]

Pennsylvania seems to be drunk in this regard.

All duplicates were renumbered. Instead, with PA 380 and PA 283, (dups to I-283 and I-380), they just gave a different internal number. Why they can't just resign PA 283 as PA 300 and PA 380 as PA 400 is beyond me.