Interstate Highway Numbering Nonsense

[kphoger]

Isn't all that harder than just looking out for signs?

So is figuring out how many exits are in between the next one and the one you want.

In other words...  Why would you want to know if your exit is next or not?  Just look for the big green sign.

[Rothman]

Why would you want to know if your exit is next or not?

Let me know if I'm going out on a limb here, but people tend to like to know where they have to get off the highway.

I suppose there is spontaneity in just getting off wherever, though.

[FrCorySticha]

There's been a lot of talk about long distance driving and mileage based exits in rural areas. But mileage based exits are far more useful than sequential based even in local driving. The local "international" airport is just 2 exits away from where I live, but that information won't help me catch my flight because it's also 21 miles from here to the local airport. The fact that I get on I-15 at exit 256, and the local airport is exit 277 helps me to figure how early I need to leave my house to catch the flight.

[FrCorySticha]

Just thought of an easy solution: every exit gets both sequential and mileage!

EXIT #10: MILE 25

That would make it so much easier, right? </sarcasm>

[Scott5114]

Just thought of an easy solution: every exit gets both sequential and mileage!

EXIT #10: MILE 25

That would make it so much easier, right? </sarcasm>

I think Vermont is actually doing this.

[cockroachking]

Just thought of an easy solution: every exit gets both sequential and mileage!

EXIT #10: MILE 25

That would make it so much easier, right? </sarcasm>

I think Vermont is actually doing this.

Indeed they are.

[kphoger]

Why would you want to know if your exit is next or not?

Let me know if I'm going out on a limb here, but people tend to like to know where they have to get off the highway.

Correct.  But people don't care if there's another exit first that they need to not exit at.  They're generally just "looking out for signs".

At least I don't care if there's another exit in between.  If I know I'm getting off at Hwy 3000 and that it's Exit #50505, then I get off where a sign with those two numbers tells me to.  As I'm getting close to that point, I don't care how many exits I need to ignore in between–but I might need to know how far it is till my exit.

[kphoger]

I was about to suggest also numbering exits in opposite directions for each side of the road, so everything you enter a state, regardless of which way you are going, will always start with 1, but based on some of the reactions here, I think I'm going to pump my brakes on that one.

As I mentioned earlier on the forum, I can't actually come up with a solid argument against it.  But personally, I'd rather the numbers start at the high end and work their way down to zero.

[MultiMillionMiler]

No that makes perfect sense. Increasing numbers you don't know when they will end, but going down to 0, there is no exit 0 or negative 1, so I totally understand that! What I was saying though, is that whichever way they go, they go the same way once crossing the state line for both directions. So a highway with 70 exits in a state, exit 2 east would exit 69 west..etc, or the way you prefer exit 69 east would be exit 2 west..etc

[US 89]

I was about to suggest also numbering exits in opposite directions for each side of the road, so everything you enter a state, regardless of which way you are going, will always start with 1, but based on some of the reactions here, I think I'm going to pump my brakes on that one.

As I mentioned earlier on the forum, I can't actually come up with a solid argument against it.  But personally, I'd rather the numbers start at the high end and work their way down to zero.

The solid argument against is that when you give directions to someplace, you don't need to change the exit number in your directions depending on what direction people are coming from.

I do prefer traveling in the direction of decreasing mileage, though.

[kphoger]

The solid argument against is that when you give directions to someplace, you don't need to change the exit number in your directions depending on what direction people are coming from.

Yeah, I hadn't quite fleshed that out.  I was thinking in terms of billboards, which would obviously be in a fixed location and therefore could have the appropriate exit number.  I was also thinking of mapping software, which could obviously handle different numbers.  But I had failed to consider the warehouse dispatcher who has to give directions to multiple truck drivers every day–and who would probably appreciate not having to care which direction the truck was coming from.

[GaryV]

Or any directions, such as in TV and radio advertisements. "Take I-32 to Exit 17 - but if you're coming from the X-direction, it's Exit 94"

[kphoger]

Or any directions, such as in TV and radio advertisements. "Take I-32 to Exit 17 - but if you're coming from the X-direction, it's Exit 94"

That's the sort of argument that was easy to dismantle.  Just change the ad to say "Take I-32 to Ballbuster Road" instead.

[Quillz]

No that makes perfect sense. Increasing numbers you don't know when they will end, but going down to 0, there is no exit 0 or negative 1, so I totally understand that! What I was saying though, is that whichever way they go, they go the same way once crossing the state line for both directions. So a highway with 70 exits in a state, exit 2 east would exit 69 west..etc, or the way you prefer exit 69 east would be exit 2 west..etc

The problem with having exit numbers always tie to the direction you're going is it creates confusion. You say "Exit 2 on Interstate 88," do you mean westbound or eastbound? I think from a strict motorist standpoint, this isn't a terrible idea, but there would need to be some kind of internal logic. It's the same reason mile markers don't reset. Even if there are realignments that no longer make the mile markers exactly a mile apart, the point is you want one unique number. Makes it easier to locate people.

Although reading some later posts, seems just referring to the actual exit name itself could work out. But I would imagine most DOTs still want some kind of internal numbering for each given exit that is fixed.

[Scott5114]

I think the sense of "reset" he was using is that whenever something changes the length of road, they typically don't go out there and change all of the mileposts from there onward to accurately reflect the new mileage.

[Quillz]

But mile markers do reset. Even on a cross country interstate like 80, mile markers drop to 0 in each state, there's no mile marker 2500 somewhere in Jersey. So what do you mean by that exactly?

If they realign the second mile so it's now only a half-mile long (as is often the case as roads generally straighten out over time due to better engineering), they're not going to renumber the mile marker to something like "1.5," they'll just leave it at "2." Likewise, if they add like 10 miles between mile marker 74 and 75, they might do something like R75, R76, R77 (standing for "realigned") and then you'll see "75" again. Because it doesn't really matter. As long as the values are unique, that is what is important.

Mile makers, at best, give a very rough sense of the route's length or where you are. It's not intended for real navigation, and never was.

[Scott5114]

But mile markers do reset. Even on a cross country interstate like 80, mile markers drop to 0 in each state, there's no mile marker 2500 somewhere in Jersey. So what do you mean by that exactly?

If they realign the second mile so it's now only a half-mile long (as is often the case as roads generally straighten out over time due to better engineering), they're not going to renumber the mile marker to something like "1.5," they'll just leave it at "2." Likewise, if they add like 10 miles between mile marker 74 and 75, they might do something like R75, R76, R77 (standing for "realigned") and then you'll see "75" again. Because it doesn't really matter. As long as the values are unique, that is what is important.

Mile makers, at best, give a very rough sense of the route's length or where you are. It's not intended for real navigation, and never was.

Most states are a bit less obvious about it than California is...

[MultiMillionMiler]

Oh I see what was meant NVM.

[J N Winkler]

Just thought of an easy solution: every exit gets both sequential and mileage!

EXIT #10: MILE 25

That would make it so much easier, right? </sarcasm>

That was actually tried (and, for a time, recommended by FHWA) back in the 1970's--it did not last long.

[Quillz]

But mile markers do reset. Even on a cross country interstate like 80, mile markers drop to 0 in each state, there's no mile marker 2500 somewhere in Jersey. So what do you mean by that exactly?

If they realign the second mile so it's now only a half-mile long (as is often the case as roads generally straighten out over time due to better engineering), they're not going to renumber the mile marker to something like "1.5," they'll just leave it at "2." Likewise, if they add like 10 miles between mile marker 74 and 75, they might do something like R75, R76, R77 (standing for "realigned") and then you'll see "75" again. Because it doesn't really matter. As long as the values are unique, that is what is important.

Mile makers, at best, give a very rough sense of the route's length or where you are. It's not intended for real navigation, and never was.

Most states are a bit less obvious about it than California is...

I actually dislike how California does things and much prefer the federal standard of just using "Mile X" instead of the weird county postmile thing California does.

[Scott5114]

But mile markers do reset. Even on a cross country interstate like 80, mile markers drop to 0 in each state, there's no mile marker 2500 somewhere in Jersey. So what do you mean by that exactly?

If they realign the second mile so it's now only a half-mile long (as is often the case as roads generally straighten out over time due to better engineering), they're not going to renumber the mile marker to something like "1.5," they'll just leave it at "2." Likewise, if they add like 10 miles between mile marker 74 and 75, they might do something like R75, R76, R77 (standing for "realigned") and then you'll see "75" again. Because it doesn't really matter. As long as the values are unique, that is what is important.

Mile makers, at best, give a very rough sense of the route's length or where you are. It's not intended for real navigation, and never was.

Most states are a bit less obvious about it than California is...

I actually dislike how California does things and much prefer the federal standard of just using "Mile X" instead of the weird county postmile thing California does.

Well, I was referring more to the R- prefixes. Most states seem like they don't draw attention to it when the mileposts are "rigged". Like, if you add a mile of road between MP 74 and MP 75, just make 74 and 75 1½ miles each. Maybe nobody will notice...

I agree that the postmile system is weird, although some of California's counties are so big that resetting at county lines at least makes some degree of sense if you squint at it. If they're going to do that, though, I wish they'd at least steal Nevada's giant enhanced postmile. I love those things. I never realized until I saw one of California's postmiles in person how utterly unreadable and inscrutable they are, especially the ones that use the stenciled text instead of FHWA Series.

[US 89]

The only thing I don't like about Nevada's enhanced mileposts is that putting the mile number sideways looks really weird when it's a single digit and there would be even more room to put it upright like a standard marker. I also never remember which way it's supposed to turn, which is really annoying if it's for mile 6 or 9.

[Vaulter]

Just thought of an easy solution: every exit gets both sequential and mileage!

EXIT #10: MILE 25

That would make it so much easier, right? </sarcasm>

That was actually tried (and, for a time, recommended by FHWA) back in the 1970's--it did not last long.

Vermont actually did something similar to this in lieu of switching to mileage based exits

https://maps.app.goo.gl/adYkrJkApzYn1NX37?g_st=ic

[Bickendan]

BTW, I am adding I-295 in NJ to the OP of this discussion. The path it takes is just ludicrous

Much better than I-95 having a physical gap in NJ. Before the parital interchange with I-276 in PA was built and going due east to the NJTP, I-95 used to go north then east, terminating at I-295/US 1... and starting again on the NJTP at what, NJ 133?.
As a result, I-295 was extended west then south into PA along what used to be I-95 to terminate at I-95/I-276, fully eliminating what was a difficult task of staying on I-95 through NJ because it was physically impossible.
Sure, NJ, PA, AASTHO, and FHWA could have used a more elegant number to fill in the post-I-95 road, such as 695 or 895, but that's akin to saying that the DC beltway *should* be two discreet numbers, like the Twin Cities' beltway, and in the end, the agencies weren't bothered, nor is Joe Q. Public.

I-82. This is looking at the details and missing the big picture. As mentioned several times, including in the PNW forum, I-82 isn't its own discreet corridor; it's part of the Puget Sound-Wasatch Front corridor. It was numbered well before I-84 existed, which entirely replaced I-80N. At time of designation, 82 was where it was meant to be in terms of The Grid.
I-80N's function, being a x0 interstate, was part of a transcontinental route, that is, Portland to New York, with mainline I-80 being the modern San Francisco to New York branch. I-84 still functions that way, though it's really thought of more as the regional Portland-Salt Lake; it's still as important as the other major x4 -- I-94.
With that all said, 84 was chosen for a lack of numbers as I-15W got 86, which would have been a bit more egregious on 84 with respect to 82.
And, in the end, 82 being north of 84 isn't even the most notable violation of a pure grid. I-99 comes to mind, and there's my favorite, I-238.
All of these, ultimately, are the exceptions that prove the rule. The I-69 triad shouldn't have happened, however.

Now. Exit numbers. I'm a classical musician. Older music tends to only have rehearsal numbers, usually denoting major sections or phrases. Most music now has measure or bar numbers as well, usually on the first measure of a staff. Some have it on every measure, but that can make the music look a little cluttered depending on the part.
In rehearsal, it is very uncommon to go from the top to the end of a piece or movement within the piece in one go. The conductor needs to stop the band or orchestra to fix a passage a section screwed up (wrong note, key signature reminder), tighten up a technical passage, provide a reminder to observe dynamics (too loud, too soft, failure to observe crescendos/decrescendos, etc), tighten up balance (not enough trombone (HA!), too much bass clarinet, who has the melody and get beneath them, and so on), interpreting what the music is doing and changing how the orchestra approaches said passage.
In a Rehearsal Number/Letter Only piece (say, a Beethoven symphony), the conductor has to count back or forward a number of measures from the nearest rehearal mark ("24 measures before Letter O"), then the players have to do the same, which is a pain when it's in the middle of a 39 measure rest and wastes time. In a mixed, even with numbers only at the first measure of a staff, they can say "Pickup to 1141" [phrase break and tempo change in Rachmonioff Symphony 2, 3rd mvt], and the wind orchestra can get to their place in the transcription that much faster than counting measures by hand.

Applying this to exit numbers: Sequential exit numbers are your rehearsal letters. They're too abstract to tell you what's happening in between, and don't provide much useful on-the-ground information. The public doesn't need to know nor really care on how many exits a route has. It is slightly more useful than California's former complete lack of exit numbers, but I'd almost go with nothing than sequential exits (in music, rehearsal numbers/letters are a must -- "15 after the double bar/8 before the Tempo Primo" is even more abstract lol).

In distance based exit numbers, they are your measure or bar numbers, providing much more granular information, including distance to your destination exit and comparing that with you and your vehicle's current capabilities (ie, how much fuel you have, when you need to take a break for food, rest, etc). The only time there's ambiguity is when heading north or east and it's not immediately clear when the state line or terminal point is. Sequential exits don't help in this regard, mind.
This is also an issue with music, although if you're playing the part, you can see how far it is.

There are some examples where sequential does work... sort of. I-95 in CT, I hear, is sequential but exits close enough in succession it's mileage anyway, and I-84/US 30 between I-5 and I-205, to make up for the two-mile mileage discrepency of the Banfield Freeway to the mainline east out to Idaho. And though sequential, the Banfield's in effect still close enough to be distance based.

[MultiMillionMiler]

I changed my mind about the exit numbers. I did honestly find the mileage more useful when I was driving on the Penn turnpike, I-81, and I-283, in the states of Maryland, Pennsylvania, West Virginia, and Virginia yesterday. I withdraw my case on that!

As for the I-95 gap, that could have easily been avoided. Common sense is that the entire turnpike should have been interstate 95. Its the fastest route, and would keep all of I-95 on the same road in one state. No one in their right mind driving from Maine to Miami would deliberately exit the jersey turnpike at exit 6, to pay an extra toll to enter Pennsylvania, and endure Philly's gridlock, extra curvy "delaware expressway", only to end up back where you would have been taking the turnpike to begin with. The original summerset freeway proposal was even more ridiculous in my opinion. Why on earth would you route I-95 not along the turnpike, when it can bypass trenton and Philly and Wilmington completely??? To put the icing on the cake, the exit numbers in the 60s from this ghost freeway now makes it look like a continuation of I-80s exit numbers, even though I-80 doesnt continue east, but it should.