Exit numbers: Distance based number or sequential?

[Duke87]

Okay, wait a second. Motorways in Europe aren't typically maintained on the national level? News to me!

I like my equation of EU countries to US states because it gives a more accurate (abeit far from perfect) comparison on political powers and certainly a much more accurate comparison in terms of scale - a factor whose importance is often underappreciated.

Secondly, it's simply for brevity's sake. Many interstates would have exit numbers stretching well past 1000 if continuously numbered by mileage (I-90 would go over 3000!). It starts to get clunky to say "take exit 2347".

A problem aggravated with mileage-based numbers. Sequential will reduce the number of 4-digit exits, though you'd still have many.

In fact, sequential would eliminate 4-digit numbers entirely. Even I-95 only has about 750 or so exits.

Perhaps get rid of the first number of 4-digit exits? At least then it would be 1000 miles between exits on the same road with the same number.

No, because then that makes the reset point arbitrary.

And, really, this proximity of same numbered exits in different states is a non-issue. Nobody in America has trouble with it or is bothered by it. It's only when exit numbers randomly reset within the same state (see I-87) that people get confused.

[english si]

Okay, wait a second. Motorways in Europe aren't typically maintained on the national level? News to me!

Given that the UK is 4 nations and Spain several, that's perhaps the wrong wording. But, for the UK, which I know best, there is no UK-wide body for road planning or maintainance. You have the the various local authorities maintaining non-trunk roads (except in Northern Ireland), the Highways Agency maintaining trunk roads in England (except in London, unless they are motorways, where trunk-roads are managed by Transport for London) and Transport Scotland, Transport Wales and the Northern Irish Roads Service dealing with Scotland, Wales and Northern Ireland. Other countries have national bodies, but in many of them it just does some of the planning and funding, co-ordinating more local places and give maintainance to more local levels (and the more federal countries are, the more devolved it is)

I like my equation of EU countries to US states because it gives a more accurate (abeit far from perfect) comparison on political powers and certainly a much more accurate comparison in terms of scale - a factor whose importance is often underappreciated.

Sure, America has got miles and miles of nothing that Europe doesn't have, but as I pointed out, Spain will have 4-digit exit numbers (and it's autonomous communities are the size of eastern US states).

And wrt roads, which is what we're talking about, they are sovereign nations (with a small pot of money at the EU to help get roads on their very limited network improved) - more autonomous than US states, where there's greater federal influence. Sure on other things they have lost political powers to the EU/Council of Europe and are more like states in a federation than sovereign countries on those grounds, but on the relevant things here (and other things, like foreign policy, taxation, etc), they are as separate as the US, Canada and Mexico. So, for equivalents of exit numbering changing at state lines, you have to look at federal countries in Europe, and it doesn't happen that exit numbers reset at geopolitical boundaries. Sure they change at country boundaries, but the road number does too (and whether they should or not is another question entirely).

No, because then that makes the reset point arbitrary.

No more arbitrary than geopolitical boundaries, plus easier ones for working out the distance to your exit.

Of course, the confusion of changing exit numbers outweighs the benefits, but if starting from scratch, it would be way more logical and useful to not reset at state lines on an inter-state system. Same goes for changing system from distance-based to sequential or, say, adding exit numbers for motorway-motorway interchanges in France and the Netherlands. If there's several different systems on one road, then making it consistent is worth it (so mileage-based in states that aren't, numbers count up/down in a state - no having resets inside the state).

[Bickendan]

Which isn't true - in North America, motorways change number when they cross country boundaries, just like in Europe and just like in America, European motorways (with some exceptions) don't change number when they cross between 'states'. However, in Europe, these roads don't reset their exit numbering when they cross state lines and don't change numbers. They may reset their chainage, but not exit numbers. So there's the difference - Spain, Germany, Belgium and the UK don't reset exit numbers when roads cross 'state' boundaries, but the US does.

It seems that way, but bear in mind that several motorways retain their number crossing from the US into Canada. I-5 transitions to BC 99 because I-5 used to be US 99, making a number change disputable. I-15 does change numbers to AB 4, and I doubt there is a historical equivalent in Montana to AB 4. But then again, AB 4 isn't a motorway. I-29 switches to MB 29, so there is no numerical switch, even though MB 29 almost immediately terminates at MB 75 (which used to cross into the US as US 75); but MB 29 isn't a motorway. I-75 crosses into Sault Ste. Marie and has no direct connection to any Canadian highways. I-69 and I-94 both become ON 402, so here we have a legitimate number swap. ON 401 doesn't cross into Detroit yet, but it will be another legitimate swap when it finally does (as either an I-x75 or x94) unless it becomes M-401. The QEW does not have any direct connection to the Interstate system on the US side, while I-190 becomes ON-405. I-81 becomes ON 137, I-87 becomes A-15. I-89 doesn't transition to a motorway on the Canadian side, instead to QC 133. I-91 does with A-55, and I-95 retains its number as NB 95.
Inclusive of BC 99, three routes maintain their number and motorway status across the border (and I/MB 29 is a stretch, as it quickly becomes MB 75, an at-grade expressway): 'US'/BC 99, I/MB 29, I/NB 95. Five maintain motorway status but switch numbers: I-69 & 94 to ON 402, I-190 to ON 405, I-81 to ON 137 (debatable due to the Thousand Islands Bridge itself), I-87 to A-15 and I-91 to A-55.
The others, I-15/AB 4, I-75, ON 401, QEW, I-87/QC 133, don't maintain motorway status on both sides, don't have a direct connection to any highways on one side of the border, or don't cross yet.

(US 99, 97, 395, 95, 93, 75, 59, 71 all cross or crossed and retained their numbers; BC 101 was created to compliment US 101 even though they never meet).

On the Mexican side, literally only two motorway cross: I-5 and I-110 with no signed number on the other side. I-905 will at some point. I-19 and I-35 terminate to city streets before crossing. The only route that crosses the Mexican/US border and retains a number is MEX/US 57, but it isn't a motorway.

[Kacie Jane]

I think we're confusing the issue here, because the issue naturally gets more confusing when you start talking about other countries.  In other countries/continents, words like "state", "nation", and "country" have a tendency to mean different things.

No, because then that makes the reset point arbitrary.

No more arbitrary than geopolitical boundaries, plus easier ones for working out the distance to your exit.

"Arbitrary" is one of those words that tends to get overused.  It's true that resetting the exit numbers after every 1000 would not be arbitrary, but I'd argue that it would be more confusing to motorists.  I think it's a perfectly reasonable expectation for exit numbers to reset at a state line, particularly if there's some geographic feature (river/mountain/etc) to mark the boundary.  If I'm driving through flat terrain and there happens to be a milepost 1000 between two exits, I'd be mighty confused with the sudden change in numbers with nothing but a little green sign on the side of the road to mark the reset point.

But then again, it could just be that here in the US, exit numbers and mileposts have always reset at state lines (at least since the advent of the Interstates, I don't know how they worked on U.S. Routes and auto trails -- although I know at least now they reset on the US Routes) so that's what I'm used to.

It may be worth starting a separate thread on "Should mileposts reset at state lines?", since I think that really is a totally separate topic from sequential vs. mileposts.

[Sykotyk]

If mileposts didn't reset at state lines, it would make for an extremely expensive exercise if, say, California were to reroute I-10 for 10 extra miles to redo the posts/exits for the rest of I-10 to Jacksonville.

Plus, in the U.S., we have very strong identity to states. Despite it being a national roadway, the state is its own entity that we're visiting.

The exits, therefore, are exits into the state. Entry points to explore said state. Waypoints in the journey through that state. They receive their own identity because of the identity of the state itself.

That's how we can see Exit 399 and Exit 1 as completely logical, expected, and a marking point from one place to another.

[vdeane]

Yeah, state lines are NOT arbitrary in the US.  There are many people who would like to see states given the same level of sovereignty that European countries had prior to the Lisbon Treaty.  And travel between the states without passing though customs is often cited as a freedom that makes America great.

Also, the words nation, state, and country mean the exact same thing to most Americans when talking about international politics (nation and country even mean the same thing when talking about local politics as well; they only acquire a different meaning when talking about Indian Reservations).

On exit numbers resetting within a state: this generally only confuses non-locals.  Using NY as an example, hardly anyone in NY thinks in terms of I-87 and I-90.  If they do, they're probably a roadgeek (note: people in Albany do think in terms of I-90, but their I-90 is just the free portion).

[Scott5114]

Only if you are in the same state as your exit, or know how far it is to get to the state line of the state where your exit is and can then add the two numbers together.

This will be the case 90% of the time. From my current location the nearest border with another state is 108 miles south of me. The next nearest one is about 117 miles north, and then I think east and west are something like 150 miles. States are big.

You're not going to mistakenly think exit 101 in Oklahoma is your exit when you're looking for Exit 101 in Iowa. You'll know you're not there yet.

[Brandon]

Only if you are in the same state as your exit, or know how far it is to get to the state line of the state where your exit is and can then add the two numbers together.

This will be the case 90% of the time. From my current location the nearest border with another state is 108 miles south of me. The next nearest one is about 117 miles north, and then I think east and west are something like 150 miles. States are big.

You're not going to mistakenly think exit 101 in Oklahoma is your exit when you're looking for Exit 101 in Iowa. You'll know you're not there yet.

Exactly.  Outside of New England and the Northeast, there aren't many places where exit numbers and mileposts reset quickly.  In Illinois, I-94 has over 60 miles before the numbers reset for Indiana, then another 45 miles before they reset for Michigan.  Even the shortest mainline interstate in Illinois (I-24) has over 37 miles before it resets for Kentucky at the Ohio River.

Europeans have little idea of the scales involved here in North America from what I've seen.  When you have an interstate like I-10 crossing through a state like Texas, you already have high numbered three digit exit numbers (almost 900 miles in the state, IIRC).  And as for sequential numbers as they have in the UK, please get real.  In the well developed UK where there's little land left, yeah, exits shouldn't be added much to the system.  However, in under developed North America, exits get added to the interstate system all the time as growth occurs.  Please remember that this is a nation as big as China with a quarter of the population, and that population is dispersed much more so than most places in Europe or East and South Asia.  Think Russia for distances and density.

[roadfro]

Replying to something on a previous page...

I wonder what they'll do with the exits on US-395 north of Reno when it re-enters California.  The exits start at 1, despite there being several hundred miles of US-395 south of there.  There is a freeway interchange at CA-203 heading to Mammoth on the south segment of the route, but it is unnumbered.  This implies the theoretical possibility of two exit 1's on US-395 if they make it a full freeway through Adelanto where it splits off I-15.

The northern segment of US 395 in California only has one exit immediately north of Reno, that's exit 8 at Hallelujah Junction (CA 70). After that interchange, the route becomes two-lane highway throughout the remainder of its time in California.

I think the best course of action for this scenario is exactly what has been done: disregard the mileage gap through Nevada and have each segment of US 395 stand on its own. Any attempt at reflecting the gap through Nevada would result in some weird unexpected exit number coming up at Hallelujah Junction.


Now I'm curious... Are there any other scenarios where a highway leaves and re-enters a state, and consideration of exit numbering (whether numbered by distance or sequentially) is needed?

[agentsteel53]

Now I'm curious... Are there any other scenarios where a highway leaves and re-enters a state, and consideration of exit numbering (whether numbered by distance or sequentially) is needed?

I believe I-24, when it ducks into Georgia momentarily, keeps Tennessee's numbers as though it were still in that state.

[Brandon]

Now I'm curious... Are there any other scenarios where a highway leaves and re-enters a state, and consideration of exit numbering (whether numbered by distance or sequentially) is needed?

I believe I-24, when it ducks into Georgia momentarily, keeps Tennessee's numbers as though it were still in that state.

Yes, it does: http://maps.google.com/maps?hl=en&ie=UTF8&ll=34.971641,-85.442734&spn=0.050429,0.077162&z=14&layer=c&cbll=34.971639,-85.44297&panoid=8MgYK6HhvejjPOt1aIFWRQ&cbp=12,338.3452770000001,,0,0&photoid=po-17761319

[TheStranger]

Now I'm curious... Are there any other scenarios where a highway leaves and re-enters a state, and consideration of exit numbering (whether numbered by distance or sequentially) is needed?

I believe I-24, when it ducks into Georgia momentarily, keeps Tennessee's numbers as though it were still in that state.

Similar example: NY 17 (future I-86) in Waverly, PA passing by US 220.

[Michael in Philly]

Now I'm curious... Are there any other scenarios where a highway leaves and re-enters a state, and consideration of exit numbering (whether numbered by distance or sequentially) is needed?

I believe I-24, when it ducks into Georgia momentarily, keeps Tennessee's numbers as though it were still in that state.

That's true.  It was even the case when every other Interstate in Georgia was numbering sequentially.

(Now, a tangent:  before I discovered, thanks to the Internet, that there were people besides me who cared about this sort of thing, and that there was therefore terminology, my term for "sequential" numbering was "consecutive."  Not sure one word's better than the other.  Any thoughts?)

[Michael in Philly]

Imagine that the US ended the horrible (if the roads are meant to be interstate, why do they not have one numbering system from end to end?) practise of resetting interstate exit numbers at state lines.

You want four-digit exit numbers?  Last time I checked, the US is a LOT bigger than the UK (or Spain).

Well, if he's English, he's used to four-digit route numbers....

[Michael in Philly]

A minor realignment might make not much difference, of the sort that usually happens with interstates.. but what about a re-route of a highway that takes 5-10 miles of previously separate road and makes it part of a larger highway -- say, starting it earlier on a road that previously was not part of any route.    Then to keep with the scheme you would need to move every later exit further down since the new exits would be 'negative' numbers compared to say, exit 1 that was previously the first on a route.   What about state highways where this sort of major change happens more often? 

I'm not sure how often these various things happen compared to each other, but, it's worth considering that when the mileage is no longer correct, the distance method starts to get kind of head-scratchy (or else would keep getting renumbered past the location of the change.. which could be at the beginning!)

But the same thing could happen on a sequentially-numbered road, because it'll (probably) have more exits, unless I'm missing something or misunderstanding you....

[Duke87]

before I discovered, thanks to the Internet, that there were people besides me who cared about this sort of thing, and that there was therefore terminology, my term for "sequential" numbering was "consecutive."  Not sure one word's better than the other.  Any thoughts?

"Consecutive" works, I suppose, but "sequential" is the official term.

I honestly had no idea what milepost numbering was until I read about it online (hey, when you're from Connecticut, how much exposure do you get to it?). I did notice that some freeways in New Jersey skipped numbers, and I did notice that the places numbers were skipped were places that the exits were further apart, but I never made the connection that the numbers were actually proportionally distance-based. I had always just assumed that numbers were skipped when the exits were further apart to allow for the potential for future exits to be added in that space.
I also thought it was just another weird thing New Jersey did (New Jersey does a lot of weird things...). Looking at other states in Rand McNally atlases, I assumed that when numbers appeared to be skipped it was because not every exit was actually shown due to lack of space.

Then I read about it and all of a sudden it all made sense, and I thought "hey, that's pretty cool! What an interesting idea! Why isn't it done around here?".

[vdeane]

Similar here.  I always assumed ON 401 was an oddity and that sequential was the norm before finding the road community on the internet.

[Michael in Philly]

before I discovered, thanks to the Internet, that there were people besides me who cared about this sort of thing, and that there was therefore terminology, my term for "sequential" numbering was "consecutive."  Not sure one word's better than the other.  Any thoughts?

"Consecutive" works, I suppose, but "sequential" is the official term.

I honestly had no idea what milepost numbering was until I read about it online (hey, when you're from Connecticut, how much exposure do you get to it?). I did notice that some freeways in New Jersey skipped numbers, and I did notice that the places numbers were skipped were places that the exits were further apart, but I never made the connection that the numbers were actually proportionally distance-based. I had always just assumed that numbers were skipped when the exits were further apart to allow for the potential for future exits to be added in that space.
I also thought it was just another weird thing New Jersey did (New Jersey does a lot of weird things...). Looking at other states in Rand McNally atlases, I assumed that when numbers appeared to be skipped it was because not every exit was actually shown due to lack of space.

Then I read about it and all of a sudden it all made sense, and I thought "hey, that's pretty cool! What an interesting idea! Why isn't it done around here?".

I, by contrast, got the connection from the start, thanks to being exposed at an early age to the Garden State Parkway.  What a difference 50 miles makes....

[jwolfer]

When I was a kid in the 70s and 80s we drove between Pt Pleasant, NJ and Jacksonville FL 1-3 times a year. i always liked the Carolinas because they had sequential exits at least going South your could tell how many miles to the next state real easily. Going North you had to know the mileage to be sure.  Early on Virginia has sequential numbers w a different sequece for the Richmond-Petersburg Turnpike( that was changed in the early 80s(?)) That was confusing for a little road geek kid... coud you imagine the mind-numbed average American with that.

[mightyace]

I learned the difference early on.

Probably because we made several visits to my mom's family in Wisconsin.

At the time, you had Pennsylvania, the Ohio Turnpike and Indiana Toll Road as sequential.  But, the free roads in Ohio, Indiana, Illinois and Wisconsin were mileage based.  Plus a trip in 1972 to South Dakota via Wisconsin and Minnesota.

Though, we mainly went through Illinois on the Tri-State Tollway which, to this day, has no exit numbers.

[Michael in Philly]

When I was a kid in the 70s and 80s we drove between Pt Pleasant, NJ and Jacksonville FL 1-3 times a year. i always liked the Carolinas because they had sequential exits at least going South your could tell how many miles to the next state real easily. Going North you had to know the mileage to be sure.  Early on Virginia has sequential numbers w a different sequece for the Richmond-Petersburg Turnpike( that was changed in the early 80s(?)) That was confusing for a little road geek kid... coud you imagine the mind-numbed average American with that.

I don't know about the Richmond-Petersburg Turnpike specifically, but I believe Virginia didn't switch to mileage-based exits on Interstates in general until the early '90s.

[OracleUsr]

When I was a kid in the 70s and 80s we drove between Pt Pleasant, NJ and Jacksonville FL 1-3 times a year. i always liked the Carolinas because they had sequential exits at least going South your could tell how many miles to the next state real easily. Going North you had to know the mileage to be sure.  Early on Virginia has sequential numbers w a different sequece for the Richmond-Petersburg Turnpike( that was changed in the early 80s(?)) That was confusing for a little road geek kid... coud you imagine the mind-numbed average American with that.

I don't know about the Richmond-Petersburg Turnpike specifically, but I believe Virginia didn't switch to mileage-based exits on Interstates in general until the early '90s.

1991, IIRC.  At the same time, the R-P Turnpike was decommissioned.

[MDOTFanFB]

Both, but the state I currently live in uses mileage base.

[connroadgeek]

I prefer sequential. Perhaps just used to it in CT where the longest stretch of highway without an exit is not even 5 miles. Most of the time it's only a mile and often times less than that to the next exit. Besides, the whole distance to the next exit thing based on mileage based numbering only works if you're familiar with the highway and know what the next number is. If I'm on mile marker and exit 173, and I'm from out of town, how do I know whether the next exit is 172, 165 or 140?

[Kacie Jane]

True, but the point typically isn't to know how far it is to the next exit, but how far it is to your exit.

Information about a random intermediate exit is fairly useless, unless of course you're driving with a small child with a smaller bladder, and you need to know whether or not he can make it to the next public restroom, or if it's "side of the road" time.