Numbering Conventions

Numbering Conventions

Highway classes under this system are designated by the color of the trailblazer and alphabetic suffixes attached to the highway number.

[200X] X-class highways, signed with white characters on a blue trailblazer, are freeways built to superior standards, analogous to the interstate system under the current highway system.
 
Unwaivered substandard freeways, or freeway segments that do not connect to other designated X-class highways shall not be designated X-class.
 
As D-class or arterial highways are upgraded to full X-class freeway standards, they may be redesignated as an X class route, retaining the same highway number, provided that the upgraded highway connects to another X-class highway. (Exceptions to the X-connects-to-X rule are granted for freeway systems in Alaska, Hawaii, and Puerto Rico.)
[193D] D-class highways, signed with white characters on a red trailblazer, include freeways that did not qualify for X-class, and expressways.
 
Freeways and expressways that do not connect to X-class or D-class highways shall not be designated D-class.
 
Arterial highways upgraded to D-class standards may be redesignated as a D-class route, provided that the upgraded highway connects to an X-class or D-class highway.
[101] Most other arterial highways will be unsuffixed, signed with black characters on white trailblazers. The letters "USA" will appear in the position reserved for suffixes on X- and D-class trailblazers.
White-on-brown trailblazers are reserved for park-service highways and routes of historic significance.
[160ALT][205BUS]

[236TRUCK] 		Bannered or suffixed routes as they exist in the current Interstate/US highway numbering system will not exist under this system. However, state transportation officials may post trailblazers such as the ones shown to the left to assist in navigation.
 
For example, an ALT route may be posted in addition to the regularly-signed highway number for regularly-used detour routes (e.g. the I-26/I-81 bypass of I-40 through the Smokies).
 
Truck trailblazers may be used to designate alternate routings for trucks traveling the signed highway.
 
In situations where the current highway numbering provides a local Bypass/Business split, the Bypass route will most likely be signed as the highway.
 
These auxiliary navigation trailblazers shall be colored as appropriate for the road conditions the auxiliary route traverses. An exception is made for Business routes, which retain the white-on-green trailblazer.
Highways traveling on toll roads shall have a yellow auxiliary "TOLL" banner displayed above the regular trailblazer.

Highways shall be numbered according to the following schedule:

100-299: Major routes. Generally transcontinental or interregional routes, or major connectors of such routes. Even numbers represent east-west routes. North-south routes are represented by odd numbers. The origin of the numbering grid is the southeast. Highway numbers increase as you move north and west. Routes ending in 0’s and 5’s are reserved for the most significant of these routes. (Exception: Highway 166.) Highway numbers may not be duplicated within the country.

300-399: Unassigned. Reserved for future expansion of the highway system (e.g. I-69, I-73, 400-series of US routes.)

400-699: Regional routes. Numbers shall be unique within a state, but may be duplicated within the country. Even=E/W, odd=N/S convention shall be observed if possible, but highways numbered in this range are not constrained by the 100-299 grid.

700-899: Local connectors, bypasses, and spurs. Numbers shall be unique within a state, and are not required to be related to "parent" routes.

900-999: Special use highways of national importance or interest. Highways in this range may include parkways, park service routes, historic routes, etc.

1-99 & 1000+: Not included in national highway numbering system. States may use national highway trailblazers on state highways numbered in these ranges, provided they comply with the highway class / trailblazer color conventions of the system. The "X", "D", and "USA" labels on national highway trailblazers shall be replaced with the state name or state abbreviation for state highways so signed.

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10 Comments


10 responses so far ↓

  • 1 L. Deszcz // 10 May 2006 at 8:53 am

    I very much like your ideas because I believe they would simplify things for the general traveler, and from a graphics standpoint I find them aesthetically pleasing, However I do have one small question. Why do you use the letter X to denote the Interstate class highways? The only reason I ask is that the letter X might be interpreted mistakenly by some people as an interchange marker due to it’s resemblance to a crossroads. And why D for the next lower standard? I’m sure you did not choose these suffixes randomly, so I am curious about the reasons for your choice of these particular letters. Is it X for X-cellent, and D for Darn Good? (Just kidding, but I am curious.)

  • 2 L. Deszcz // 10 May 2006 at 12:25 pm

    Reposting to amend my previous comment, I must also point out that the X might be confused as a rail crossing indication. And as for the D class, I must also point out that the letter D is, on a grading system, usually used to denote a near failure. Hardly an acceptable grade for a Class 2 highway! Personally, I feel it would be better to simply use a numerical (1 or 2) suffix to denote either a Class 1 or Class 2 highway. True, some people might be confused by a second numeral below the main route number, but I think it is still better than what seems to be randomly chosen letters of the alphabet. Plus it would allow for a more “orderly” expansion of the classification system, if need be. The USA and Historical suffixes, however, are fine as they are, as are your shape and color standards, which suggest and reflect the original Interstate and route signage now in use nationwide, and use the Red, White and Blue very effectively. All told, a very nice piece of work, which it would be interesting to see implemented.

  • 3 Bucky Edgett // 26 Jun 2006 at 12:18 am

    Nope, sorry, don’t like it. Absolutely necessary to rationalize the system, but this is too complex to be immediately or “intuitively” informative and expandable.

    1. All roads of the same class (X, D, etc.) should be numbered in numerical order based on their starting point in Latitude or longitude. (Analagous to using mileage points to number exits.) If “routes” in the same orientation “cross,” bounce them (instead of crossing them) to maintain the geo relationship.

    2. Locals, bypasses, spurs get hyphenated compound numbers formed of the main route number and the mileage at which the l/b/s originates.

  • 4 Ian Wilson // 16 Sep 2006 at 4:06 pm

    Just to put things into prospective here in the United Kingdom our road system signage uses “M” for your “Interstate” M standing for Motorway, we have a numbering system to go along with the letters. The first motorway was the “M1″ and so on…We then move down a scale to “A” roads then “B” roads and so on these also have numbering too you have A38 or A45, and the B roads could be B456 or simular.
    The system is national so no confusing national or state conflicting numbering.

  • 5 L. Deszcz // 12 Dec 2006 at 1:20 pm

    Just one other thing, you should use the full word “Business” on your business trailblazers because I can almost picture the poor foreigners and confused elderly people standing around the highway markers waiting for the bus to come. It seems like a cruel thing to say, but you know it would probably happen.

  • 6 C. Carter // 2 Aug 2007 at 2:14 am

    Your idea is very weird, why change something that isn’t broken, the u.S. has been use to the way we have our numbering system for the past 53 years.

  • 7 MikeTheActuary // 2 Aug 2007 at 7:07 am

    For an explanation of why, you should check out the “Intention/Premise” page…but the short version is that the existing system is redundant, unable to follow its own conventions, and currently downright messy…and while I don’t expect it to be replaced, like many other roadgeeks I can dream. :)

  • 8 Deke // 16 Aug 2007 at 7:56 pm

    Hi, I believe a major distinction between the interstate system and the US Highway systems is that Interstates are largely federally funded, while US Highways are simply state highways which receive an AASHTO designation. I might be way off, but I think this is why it is difficult to treat them the same.

    Great roadgeek website.

    Deke

  • 9 Craig // 5 Mar 2008 at 10:28 pm

    I have a thought for 300-series numbers: They could be used for routes well off the mainland in outlying areas that would not fit well in the grid. They could be clustered by region used.

  • 10 C. Carter // 29 Mar 2008 at 9:25 pm

    I am starting to warm to the idea but why don’t we try something like the Europeans like something like this:
    A# - For a Interstate
    B# - For a US Route
    C# - For a State Route
    D# - For a County Route

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