Why are there not 4 digit interstates?

[texaskdog]

It would make more sense than repeating the 3-dis

[kphoger]

I'd rather see 3-digit numbers that are unrelated to the parent route.
I-238 and I-99 aren't bad, they're groundbreaking.

[texaskdog]

I'd rather see 3-digit numbers that are unrelated to the parent route.
I-238 and I-99 aren't bad, they're groundbreaking.

Or 5 digits, in LA there could be a 90210

[Max Rockatansky]

I'd rather see 3-digit numbers that are unrelated to the parent route.
I-238 and I-99 aren't bad, they're groundbreaking.

Wouldn't be a bad idea to do a secondary numbering system for Interstates on Spur routes.  I would prefer it would still be even for E/W and off for N/S though.  Hell you could just make Interstate colored state route shields for any state highways that met standards.

[hotdogPi]

I'd rather see 3-digit numbers that are unrelated to the parent route.
I-238 and I-99 aren't bad, they're groundbreaking.

Or 5 digits, in LA there could be a 90210

I-210 and "90210" are in different parts of the LA metro area.

[frankenroad]

I'd rather see 3-digit numbers that are unrelated to the parent route.
I-238 and I-99 aren't bad, they're groundbreaking.

I hope you are kidding.   Those two routes are the abomination of the Interstate System.

[kphoger]

I'm not kidding.  I prefer random route numbers over any organized system, because organized systems invariable fall apart at some point.

[vdeane]

I'm not kidding.  I prefer random route numbers over any organized system, because organized systems invariable fall apart at some point.

Plus we wouldn't have all this 2di duplication; they could just pull a number from another part of the country.  Of course, it wouldn't solve the issues with I-74 and I-69.

[Revive 755]

It would make more sense than repeating the 3-dis

1) Because not enough states have run out of available 3di routes yet?  Even California should not count IMO, since I-180 is available (and also IMO California can either grant an exception to their policy on duplicating route numbers, renumber CA 180, or do without an interstate designation).

2) Not everyone feels there is anything wrong with having multiple instances of the same 3di route.  I can vouch from experience that there are non-roadgeeks out there that would not have a problem with even having the same 3di used twice in the same state - such as using I-470 in Missouri for both routes in the Kansas City and St. Louis areas.  I would also have to wonder if some of the states DOT's would feel the same, especially since Iowa at one time seems to have wanted to have an I-280 on each end of the state. http://www.kurumi.com/roads/3di/i280.html#280ne

[Scott5114]

In most states, route numbers of any type do not exceed three digits. Texas and Kentucky are the exceptions rather than the rule. Why this is the case is up for debate. It is difficult to fit a four-digit route into most standard shields without compromising legibility (in Texas this is not a problem, because only FM routes bear 4-digit numbers, and they are so minor that it doesn't matter that much). It may also be more difficult for people to remember a 4-digit number compared to a 3 digit one.

[nexus73]

I'd rather see 3-digit numbers that are unrelated to the parent route.
I-238 and I-99 aren't bad, they're groundbreaking.

Or 5 digits, in LA there could be a 90210

That would be the Beverly Hills Freeway...LOL!

Rick

[nexus73]

In most states, route numbers of any type do not exceed three digits. Texas and Kentucky are the exceptions rather than the rule. Why this is the case is up for debate. It is difficult to fit a four-digit route into most standard shields without compromising legibility (in Texas this is not a problem, because only FM routes bear 4-digit numbers, and they are so minor that it doesn't matter that much). It may also be more difficult for people to remember a 4-digit number compared to a 3 digit one.

Louisiana has 4 digit state routes.

Rick

[epzik8]

Because there just aren't four-digit Interstates, the exception being Hawaii.

[cpzilliacus]

In most states, route numbers of any type do not exceed three digits. Texas and Kentucky are the exceptions rather than the rule. Why this is the case is up for debate. It is difficult to fit a four-digit route into most standard shields without compromising legibility (in Texas this is not a problem, because only FM routes bear 4-digit numbers, and they are so minor that it doesn't matter that much). It may also be more difficult for people to remember a 4-digit number compared to a 3 digit one.

Virginia has had state secondary system route numbers that edge up into five digits in some cases, and has had four digit secondaries for as long as I can remember.

There are also "F" routes (frontage roads, considered secondary system roads) and "T" routes (secondary system routes within the corporate limits of small towns). I know of "F" routes with an F followed by three numbers; and T routes followed by four numbers.

[Aerobird]

It would make more sense than repeating the 3-dis

...this is a thing I simply cannot comprehend. Should Georgia not use State Road 369 because there's a State Road 369 in Florida? The same applies to 3dis....

[Anthony_JK]

In most states, route numbers of any type do not exceed three digits. Texas and Kentucky are the exceptions rather than the rule. Why this is the case is up for debate. It is difficult to fit a four-digit route into most standard shields without compromising legibility (in Texas this is not a problem, because only FM routes bear 4-digit numbers, and they are so minor that it doesn't matter that much). It may also be more difficult for people to remember a 4-digit number compared to a 3 digit one.

Louisiana is another exception, since they do have 1xxx and 3xxx state routes.

[hotdogPi]

Should Georgia not use State Road 369 because there's a State Road 369 in Florida? The same applies to 3dis....

Remember that the 3-digit US routes don't have duplication, unlike 3-digit Interstates.

[cjk374]

In most states, route numbers of any type do not exceed three digits. Texas and Kentucky are the exceptions rather than the rule. Why this is the case is up for debate. It is difficult to fit a four-digit route into most standard shields without compromising legibility (in Texas this is not a problem, because only FM routes bear 4-digit numbers, and they are so minor that it doesn't matter that much). It may also be more difficult for people to remember a 4-digit number compared to a 3 digit one.

Louisiana is another exception, since they do have 1xxx and 3xxx state routes.

Louisiana also has 5-digit routes when you count the hyphenated 4-digit routes.

How about this idea: should I-220 ever be completed around Shreveport/Bossier City, you could number the northern half I-220-1 & the southern half I-220-2. 

That is what I love about my home state...uniqueness.     

[kphoger]

Does West Virginia have any secondary state route spurs ("fractional" routes) branching off from a three-digit route? If so, then that would be another state with four digits.

[Max Rockatansky]

Could be how like Florida does things with three digits.  All the X0 are the major east/west routes and the X5s are still major north/south.  The gaps are filled in with three digit numbers that start with the first digit of whatever even number they are in; example everything south of 50 would be in the 5XX band to 60.  Of course that would have required a 50 and 60 from the get-go and obviously there was a thought that it would cause confusion.

[GreenLanternCorps]

I'd rather see 3-digit numbers that are unrelated to the parent route.
I-238 and I-99 aren't bad, they're groundbreaking.

A riot is an ugly thing.  Und I think that it is just about time that we had one!

[route17fan]

How would such a numbering system work? Granted, rules are meant to be broken and as such there are always violations, but generally, even numbered routes are loops and odd numbered routes are spurs (I know all know this; just repeating for the point of the question) - if such a numbering system would be implemented, what would be the new guidelines?

[kphoger]

How would such a numbering system work? Granted, rules are meant to be broken and as such there are always violations, but generally, even numbered routes are loops and odd numbered routes are spurs (I know all know this; just repeating for the point of the question) - if such a numbering system would be implemented, what would be the new guidelines?

I see three possibilities:

(1) 4di would be limited to spurs and loops.  So, for example, one of the I-680 iterations could be numbered I-1280 instead to avoid duplication.  This would be the simplest and cleanest.

(2) 4di would be limited to spurs and loops of already-3di routes.  So, for example, New York's I-495 could be numbered I-1295 instead, indicating that it branches off from I-295 rather than I-95.  This would be almost as simple and clean as #1, and it makes more sense in my opinion  However, it isn't necessarily any more intuitive to Joe Driver than #1.

(2) The available pool of parent Interstates would be expanded to 1—999 and the available pool of spurs and loops would change to be 1000—9999.  This would require all current spurs and loops to be renumbered for the system to make any sense.  In addition, making room for more parent routes would only matter if you [a] renumbered a whole bunch of existing trunk Interstate highways or [2] don't care about breaking the grid.

[hbelkins]

Does West Virginia have any secondary state route spurs ("fractional" routes) branching off from a three-digit route? If so, then that would be another state with four digits.

Yes. They're signed "xxx/xx." I don't know if I've ever seen a three-digit "denominator," though.



As to the original question, if you have 10 "children" off a single "parent" in an individual state, then I don't see why you couldn't have a 4di. New York has used up all its x90's, so should a new one be designated, it should be I-1090.

I can see North Carolina needing a 4di at the rate they're commissioning interstates.

I know of no FHWA rule that would prohibit a 4di.

[kphoger]

Does West Virginia have any secondary state route spurs ("fractional" routes) branching off from a three-digit route? If so, then that would be another state with four digits.

Yes. They're signed "xxx/xx." I don't know if I've ever seen a three-digit "denominator," though.

Sure enough!  I found this route shield for WV-119/13 on GSV:


Are Virginia's 5-digit routes signed with shields?  If not, then that takes us to two states with signed 5-digits route shields (LA, WV).