What I mean here is that since there is supposed to be at least one mile between interstate exits, what instances are there exits less than a mile of each other? Here in Jackson, exits 99 (Meadowbrook Road) and 100 (Northside Drive--my exit to get to my house) on I-55 are half a mile apart. Also, in the downtown area, exits 96A (Pearl Street) and 96B (High Street) are about half a mile away (if not less) from each other. 96B and 96C (Fortification Street) are about a half from each other too. However, since they all are part of exit 96, I may not count that as a violation.
Further north on I-55 into Madison County, the Natchez Trace Parkway (105A) and the Ridgeland/Old Agency Road (105B) exits are probably about a quarter of a mile apart (though I'm estimating here). Again, possibly not a violation since they share the same exit number.
QuoteWhat I mean here is that since there is supposed to be at least one mile between interstate exits
Wait, what? Who/what exactly said that- I've never heard of such a rule. There are hundreds if not thousands of exits within a mile of each other- I can't imagine that's a violation of a standard. I'm also not sure why it would be better to have 96A/96B than 96/97- if such a standard is in play, I can't imagine why suffixed exits would be advocated while entirely different numbers would be discouraged (especially if they're entirely different interchanges like your I-55 Jackson example)- that essentially implies that exits have to be either really close together or more than a mile apart, which would be an.... interesting standard. Please enlighten me.
General FHWA policy is for freeway interchanges to be at least 1 mile apart in urban areas and 3 miles apart in rural areas. Of course, there are a gazillion exceptions to that, plus waivers can be granted if needed (i.e. you have two major routes intersecting the freeway at less than the desired distance).
I wouldn't exactly call it a "violation", because A) different standards at the beginning of Interstate construction, and B) waivers can and have been granted, and in the case of Interstates would have to be approved by FHWA to begin with.
When there are exits such as 96A and 96B doesn't it normally apply at cloverleafs where each off-ramp is called A and B?
As for numbering closely spaced interchanges couldn't a little cheating in the distances be allowed to free up a number. For example, there's an interchange at mile 95 and three close together at mile 97. Couldn't they be numbered 96, 97, 98 even though they aren't at their respective distances?
Quote from: Truvelo on June 22, 2010, 11:02:53 AM
When there are exits such as 96A and 96B doesn't it normally apply at cloverleafs where each off-ramp is called A and B?
It can also be used to denote two exits within a mile, the example nearest to me here in Sacramento being US 50 eastbound exits 8A (59th Street) and 8B (65th Street).
Interestingly, California ONLY uses lettering for a cloverleaf (or any multi-ramp interchange) when there are seperate ramps that pull off the freeway mainline, and not when there is a collector-distributor road or one ramp that splits into two. (i.e. Florin Road from Route 99 is Exits 293A and 293B, but Watt Avenue off of US 50 which utilizes a pair of collector/distributor lanes (one in each direction) is just Exit 11).
on I-95 in Mass, there is a collector/distributor road that is signed "exits 22-23-24" (or is it 23-24-25? I don't remember).
reason being, that c/d road is the old alignment!
Quote from: TheStranger on June 22, 2010, 11:16:51 AM
Quote from: Truvelo on June 22, 2010, 11:02:53 AM
When there are exits such as 96A and 96B doesn't it normally apply at cloverleafs where each off-ramp is called A and B?
It can also be used to denote two exits within a mile, the example nearest to me here in Sacramento being US 50 eastbound exits 8A (59th Street) and 8B (65th Street).
Or a lot more than two. The most extreme example I know of occurs in Kansas City.
http://maps.google.com/maps?ll=39.102624,-94.58117&spn=0.020015,0.028281&z=15
Edit: shortened URL.
Quote from: Jim on June 22, 2010, 11:33:27 AMThe most extreme example I know of occurs in Kansas City.
Those exits on the northern section are too closely spaced. The weaving sections are just tiny and is it really necessary to have access to so many surface streets? Closing some of them would reduce the exit numbers by a few letters :cool:
Quote from: TheStranger on June 22, 2010, 11:16:51 AM
Interestingly, California ONLY uses lettering for a cloverleaf (or any multi-ramp interchange) when there are seperate ramps that pull off the freeway mainline, and not when there is a collector-distributor road or one ramp that splits into two. (i.e. Florin Road from Route 99 is Exits 293A and 293B, but Watt Avenue off of US 50 which utilizes a pair of collector/distributor lanes (one in each direction) is just Exit 11).
That's fairly SOP around the US for C/D ramps on cloverleafs. Outside of California, we've used that system for decades. Nice to see California finally caught up with the rest of us.
What's even more interesing is the use of a single unsuffixed number for one direction with C/D lanes and the suffixes used for the direction without C/D lanes. Example: I-55 and US-12/20/45 in Illinois. Nbd is Exits 279 A&B while Sbd is Exit 279 due to the C/D lane.
Quote from: corco on June 22, 2010, 02:52:43 AM
QuoteWhat I mean here is that since there is supposed to be at least one mile between interstate exits
Wait, what? Who/what exactly said that- I've never heard of such a rule. There are hundreds if not thousands of exits within a mile of each other- I can't imagine that's a violation of a standard. I'm also not sure why it would be better to have 96A/96B than 96/97- if such a standard is in play, I can't imagine why suffixed exits would be advocated while entirely different numbers would be discouraged (especially if they're entirely different interchanges like your I-55 Jackson example)- that essentially implies that exits have to be either really close together or more than a mile apart, which would be an.... interesting standard. Please enlighten me.
Mississippi, like most other states, numbers its interstate exits in accordance to mileage (like a mile marker) rather than sequential order (which very few states do now). Since the three downtown exits fall within the 96-mile range, that could explain why those exits are labeled A, B and C.
Quote from: froggie on June 22, 2010, 07:22:35 AM
I wouldn't exactly call it a "violation", because A) different standards at the beginning of Interstate construction, and B) waivers can and have been granted, and in the case of Interstates would have to be approved by FHWA to begin with.
I only used "violation" for lack of a better term.
Quote from: Brandon on June 22, 2010, 12:50:38 PM
That's fairly SOP around the US for C/D ramps on cloverleafs. Outside of California, we've used that system for decades. Nice to see California finally caught up with the rest of us.
California exit numbering practices seem extend that to ANY single-ramp exit though (not just cloverleafs with C/D), regardless of how many auxiliary ramps come out. This results in signage like the following, where both the ramp from 5/99 to 80 east AND 80 west receive "Exit 522" designations -
https://www.aaroads.com/california/images005/i-005_sb_exit_522_02.jpg
Wouldn't this be designated as an A/B situation in other states?
In Oklahoma, here is how suffixes are handled with C/D roads:
For cloverleaves with C/D roads, one exit number is assigned (e.g. Exit 109 for Main Street in Norman). This exit number is on the gore signage where the C/D road departs from the mainline (often in a narrow vertical format). Gore signage at each of the ramps simply states the destination (e.g. "Main Street/Westbound").
For multiple interchanges connected by C/D roads but otherwise unrelated, one suffix will be assigned for each interchange (e.g. Exits 108AB in Norman). No gore signage is placed where the C/D road departs from the mainline. Exit tabs read "EXITS 108A-B". Gore signage at each of the ramps is the typical exit number setup.
Quote from: TheStranger on June 22, 2010, 01:04:41 PM
Wouldn't this be designated as an A/B situation in other states?
Not in New York. I-81 has a couple of exceptions, but one is the result of a reconfigured interchange, and the other results from separate exits being connected by a C/D road.
New York uses N-S and E-W suffixes (as opposed to A-B) in cases where more than one ramp serves the same "Exit". I don't recall seeing that practice in any other state but I don't know if it's unique to New York.
New York's I-90 east of Albany has an Exit 11E and 11W, with separate ramps, for the interchange with US 9 and 20 when approaching eastbound:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fwww.teresco.org%2Fpics%2Fsigns%2F20071005%2Fexit11w.jpg&hash=6348d5abc1b5b8d7791734f91f1a6b155f28b49b)
but just a single ramp for Exit 11 when approaching westbound.
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fwww.teresco.org%2Fpics%2Fsigns%2F20071007%2Fexit11.jpg&hash=3e384a64a4bde7ace1e215cae21dcd18b09a0022)
Quote from: TheStranger on June 22, 2010, 01:04:41 PM
Quote from: Brandon on June 22, 2010, 12:50:38 PM
That's fairly SOP around the US for C/D ramps on cloverleafs. Outside of California, we've used that system for decades. Nice to see California finally caught up with the rest of us.
California exit numbering practices seem extend that to ANY single-ramp exit though (not just cloverleafs with C/D), regardless of how many auxiliary ramps come out. This results in signage like the following, where both the ramp from 5/99 to 80 east AND 80 west receive "Exit 522" designations -
https://www.aaroads.com/california/images005/i-005_sb_exit_522_02.jpg
Wouldn't this be designated as an A/B situation in other states?
Nope. In Illinois, if it is a single ramp leaving the mainline, it gets one exit number. For example, the exit for I-355 from I-55 (both directions) splits into ramps for Nbd and Sbd I-355 after leaving the mainline. Thus, it gets a single unsuffixed exit number, in this case Exit 269.
EDIT: In fact, I've no idea why California chose two signs for that exit when one would do. And for goodness sakes, just put the tab above the sign. It looks better.
Quote from: golden eagle on June 22, 2010, 01:20:23 AM
What I mean here is that since there is supposed to be at least one mile between interstate exits, what instances are there exits less than a mile of each other? ...
I think you've confused policy with guidelines. I believe it is AASHTO's
A Policy on Geometric Design of Highways and Streets (aka the "Green Book") that recommends spacing of at least one mile between interchange ramps, and two miles between a system (freeway-to-freeway) interchange and other service (local) interchanges. This is obviously a guideline, as there are probably way too many examples of interchanges being closer than one mile to list--many of which likely date to before the 1-mile spacing recommendation was adopted.
However, the Green Book is generally developed with significant input from FHWA, the state DOTs, and various research agencies, so the Green Book is generally regarded as the Bible of U.S. street and highway design. Most public agencies and DOTs either adopt the Green Book as their design standard or base their own design guidelines substantially from it. In the case of closely-spaced interchanges, to deviate from the recommendations of the Green Book, engineers would likely have to document a rationale for this or otherwise design some mitigating measure to deal with weaving/merging issues (C/D roads, braided ramps, etc.).
Quote from: Truvelo on June 22, 2010, 11:02:53 AM
As for numbering closely spaced interchanges couldn't a little cheating in the distances be allowed to free up a number. For example, there's an interchange at mile 95 and three close together at mile 97. Couldn't they be numbered 96, 97, 98 even though they aren't at their respective distances?
Nevada DOT has done this on occasion. The best example is I-80 in Reno/Sparks. Due to the close spacing of interchanges east of Wells Avenue, the US 395 interchange and all exits in Sparks are actually numbered sequentially. The result ends up being that Exit 21 (the last exit in the urban area) is roughly three or four miles from Exit 22 (the first exit outside the urban area). Part of the reason I think this was done was to avoid labeling the major interchange at US 395 as Exit 14B, when it's clearly a separate entity from the minor service interchange of Wells Avenue (Exit 14, 14A if sequential).
Quote from: TheStranger on June 22, 2010, 01:04:41 PM
California exit numbering practices seem extend that to ANY single-ramp exit though (not just cloverleafs with C/D), regardless of how many auxiliary ramps come out. This results in signage like the following, where both the ramp from 5/99 to 80 east AND 80 west receive "Exit 522" designations -
https://www.aaroads.com/california/images005/i-005_sb_exit_522_02.jpg
Wouldn't this be designated as an A/B situation in other states?
No. Even though the south-to-east ramp crosses over I-80 on the same bridge as the mainline I-5 south lanes (separated by a curb island), both directions exit at the same exit gore (Exit 522) and split in half downstream of the exit gore.
Perhaps if this was a C/D setup in some other states, you might get a situation where the main exit is labeled Exit 522, then the ramp to I-80 West would be 522A and the ramp to I-80 East would be 522B. For this exact ramp configuration, most other states would likely combine these two BGSs into one sign panel.
Quote from: Jim on June 22, 2010, 03:30:39 PM
New York uses N-S and E-W suffixes (as opposed to A-B) in cases where more than one ramp serves the same "Exit". I don't recall seeing that practice in any other state but I don't know if it's unique to New York.
As far as I can recall, this is primarily a New York thing (although it may have been used in other areas previously).
Using direction letters (N, S, E, W) as a suffix for exit numbers is prohibited in the national MUTCD.
Quote from: Brandon on June 22, 2010, 03:50:22 PM
EDIT: In fact, I've no idea why California chose two signs for that exit when one would do.
CalTrans SOP is to replace previously-existing signage with reflective replacements that use the same exact text and sign height/width whenever possible, as opposed to installing a new sign with different formatting, new legends, and a wider area to accomodate more of the gantry space.
Quote from: Truvelo on June 22, 2010, 12:00:16 PM
Quote from: Jim on June 22, 2010, 11:33:27 AMThe most extreme example I know of occurs in Kansas City.
Those exits on the northern section are too closely spaced. The weaving sections are just tiny and is it really necessary to have access to so many surface streets? Closing some of them would reduce the exit numbers by a few letters :cool:
It's very unique. Closing some of them would be a sad day ;)
I-4, in the Deltona-Orange City-DeBary triad, used to have Exits 53-CA and 53-CB at present-day Exit 111. Old Exit 53 (now Exit 108) was for Dirksen Drive and the only other road, Enterprise Road, crosses I-4 at an angle with not much room for an interchange on the east side. I could understand it if they were 53-AA and 53-AB, but I don't understand the logic of using the "C" unless it was to differentiate the "A" and "B" "sub-suffixes".
Tennessee is inconsistent in signing collector-distributor roads and ramps. I need go no further than the I-65/TN 840 junction for an example.
Here's the sign for TN 840 on I-65 north:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Ffarm3.static.flickr.com%2F2722%2F4282648637_f2a6ebe52f_m.jpg&hash=749828642f7e9b9499d5f4f2bc828d05ba5c445d)
This is a "distributor" road only but the ramps to TN 840 East (A) and West (B) are clearly labeled on the mainline.
The empty space will, most likely, be filled with Memphis when 840 is finished.
Here's the sign at the gore point: (It could be called the Al Gore [Sr.] point as I-65 in Tennessee is the The Albert Arnold Gore Sr. Memorial Highway (http://en.wikipedia.org/wiki/Interstate_65_in_Tennessee). :sombrero:)
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Ffarm3.static.flickr.com%2F2688%2F4317670960_47d0fa8a91_o.jpg&hash=82787493baa7831cbf0052ee88b696d3682d80ab)
Here the I-65 exit is listed as Exit 31 without any suffixes.
However when you have to pick north or south:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Ffarm3.static.flickr.com%2F2781%2F4317671446_b8a96fb618_b.jpg&hash=d74fba1eb82ecdad98369bd0747a6c64cbeeca93)
Exits 31A and 31B appear.
All photos here appear in the TN Road Photos collection on Flickr. (http://www.flickr.com/photos/mightyace/sets/72157615512333764/)
^ It doesn't make sense to me for the ramp to have separate suffixes when it simply divides in half. It'd be one thing if it was a C/D road, where one ramp branches followed by another with other movements merging in between them. In essence, there is no Exit 31B in this example.
QuoteMississippi, like most other states, numbers its interstate exits in accordance to mileage (like a mile marker) rather than sequential order (which very few states do now). Since the three downtown exits fall within the 96-mile range, that could explain why those exits are labeled A, B and C.
I get that part- what I don't get is why three completely different interchanges that are so close to each other they have to share the same exit number wouldn't count as "violations" but two interchanges just far enough apart that they have different exit numbers would. If there's ramps shared, I get why that works, but in the Jackson example 96 A, B, and C don't share a single ramp- they're completely independent of each other.
Quote from: Jim on June 22, 2010, 03:30:39 PM
New York uses N-S and E-W suffixes (as opposed to A-B) in cases where more than one ramp serves the same "Exit". I don't recall seeing that practice in any other state but I don't know if it's unique to New York.
Not all of New York. The Rochester and Buffalo areas use A/B.
I-90 & I-94 in Chicago has a ramp for every street in the downtown area, with left entrances and right exits just north of I-290.
Quote from: deanej on June 23, 2010, 12:35:32 PM
Quote from: Jim on June 22, 2010, 03:30:39 PM
New York uses N-S and E-W suffixes (as opposed to A-B) in cases where more than one ramp serves the same "Exit". I don't recall seeing that practice in any other state but I don't know if it's unique to New York.
Not all of New York. The Rochester and Buffalo areas use A/B.
I've seen a couple of E/W designations still alive & well on the mainline Thruway (specifically exits for NY 33 and Walden AVE).
There is an Exit 0 from Kentucky to Indiana on I-65.
Quote from: citrustaco on July 30, 2010, 01:20:26 PM
There is an Exit 0 from Kentucky to Indiana on I-65.
Yeah, the exit to downtown Jeffersonville. But there's no violation. :no:
ETA: And before people try to spout off more Exit 0s here, it's already been done (https://www.aaroads.com/forum/index.php?topic=1672.0). :p
Another Indiana example, currently there are two Exit 22s on I-69, one in Gibson County near I-64 on the new stretch of I-69 and one in Madison County in the central part on the traditional part of I-69. However, this should be rectified soon as INDOT is petitioning to AASHTO to get the I-69 route in Southern Indiana approved so they can change the exit numbers further north. Exit 0 at I-465 will become Exit 184 and what is now Exit 22 will be Exit 206.
Thanks for the heads up on I-69 and renumbering.
What are they using as the new zero mile marker? If it's anything other than the future Ohio River crossing, they're just going to have to renumber the exits again...
Quote from: Jim on June 22, 2010, 03:30:39 PM
New York uses N-S and E-W suffixes (as opposed to A-B) in cases where more than one ramp serves the same "Exit". I don't recall seeing that practice in any other state but I don't know if it's unique to New York.
Mississippi used to do this before they switched to mileage based exit numbers
Quote from: citrustaco on July 30, 2010, 01:20:26 PM
There is an Exit 0 from Kentucky to Indiana on I-65.
This is common in Alabama.
Quote from: Jim on June 22, 2010, 03:30:39 PM
New York uses N-S and E-W suffixes (as opposed to A-B) in cases where more than one ramp serves the same "Exit". I don't recall seeing that practice in any other state but I don't know if it's unique to New York.
I recall seeing some of these in Connecticut.
Quote from: Jim on June 22, 2010, 03:30:39 PM
New York uses N-S and E-W suffixes (as opposed to A-B) in cases where more than one ramp serves the same "Exit". I don't recall seeing that practice in any other state but I don't know if it's unique to New York.
PA has also done this.
And here's an example: I-80 WB Exit #212W (http://maps.google.com/?ie=UTF8&ll=41.049081,-76.836276&spn=0.008415,0.01929&z=16&layer=c&cbll=41.049152,-76.836388&panoid=jD-L_GpNvcSHh1y6Rukeng&cbp=12,265.77,,0,11.31)
Yet, the EB side uses A&B.
All I've seen is "A,B,C, etc" I think it would be interesting to see an "E,W,N, or S" one. But I don't think that's gonna happen any time soon. ;)
Quote from: tdindy88 on July 30, 2010, 03:43:53 PM
Another Indiana example, currently there are two Exit 22s on I-69, one in Gibson County near I-64 on the new stretch of I-69 and one in Madison County in the central part on the traditional part of I-69. However, this should be rectified soon as INDOT is petitioning to AASHTO to get the I-69 route in Southern Indiana approved so they can change the exit numbers further north. Exit 0 at I-465 will become Exit 184 and what is now Exit 22 will be Exit 206.
Because of the I-74 concurrency with I-465, I-74 in Indiana has two of the following exit numbers: exit 4, exit 8, and exit 52. Depending on how the new US 136/Crawfordsville Rd exit is numbered, there could also be two exit 15s. A similar situation with I-69 where it overlaps I-465 may permanently create duplicate exit numbers there as well.
Quote from: BigMatt on July 31, 2010, 01:45:09 AM
All I've seen is "A,B,C, etc" I think it would be interesting to see an "E,W,N, or S" one. But I don't think that's gonna happen any time soon. ;)
Dunno about all four, but there are definitely a couple cases with three:
- The Wilbur Cross Parkway (CT 15) northbound has exits 68W-N-E (http://maps.google.com/?ie=UTF8&hq=&hnear=New+York&ll=41.51817,-72.774564&spn=0.003912,0.007231&z=17&layer=c&cbll=41.518105,-72.77464&panoid=lkQckhR7xQQbtF1uBa1Mnw&cbp=12,44.67,,0,0.46)for I-691, I-91, and CT 66 (respectively)
- The Belt Parkway westbound has exits 17N-W (http://maps.google.com/?ie=UTF8&hq=&hnear=New+York&ll=40.665348,-73.828919&spn=0.003963,0.007231&z=17&layer=c&cbll=40.665358,-73.829036&panoid=65aWDcelQRlwSRtF7-1VcQ&cbp=12,278.55,,0,-5.28)-S (http://maps.google.com/?ie=UTF8&hq=&hnear=New+York&ll=40.666683,-73.835753&spn=0.003963,0.007231&z=17&layer=c&cbll=40.666739,-73.836025&panoid=ZGrVAh0iF1FK0NXbDhqzCg&cbp=12,298.18,,0,-22.37) for Cross Bay Boulevard north/south and NY 27 (North Conduit Avenue) west.
I believe that the exit numbers on interstate multiplexes should use the mileage of the lowered number interestate.
If that is correct, when I-39 was extended over I-90 and I-90/94 in Wisconsin, WIDOT didn't change the interstate exit numbers to reflect I-39's mileage. They still use I-90s numbers.
Quote from: SEWIGuy on August 02, 2010, 12:25:42 PM
I believe that the exit numbers on interstate multiplexes should use the mileage of the lowered number interestate.
If that is correct, when I-39 was extended over I-90 and I-90/94 in Wisconsin, WIDOT didn't change the interstate exit numbers to reflect I-39's mileage. They still use I-90s numbers.
Yes, they still use I-90's numbers (why change?). I-39 also uses US-51's numbers north of Portage.
Quote from: Brandon on August 02, 2010, 12:42:22 PM
Quote from: SEWIGuy on August 02, 2010, 12:25:42 PM
I believe that the exit numbers on interstate multiplexes should use the mileage of the lowered number interestate.
If that is correct, when I-39 was extended over I-90 and I-90/94 in Wisconsin, WIDOT didn't change the interstate exit numbers to reflect I-39's mileage. They still use I-90s numbers.
Yes, they still use I-90's numbers (why change?). I-39 also uses US-51's numbers north of Portage.
and "South" (WIS 78's #s were an extension southward of US 51's numbers) to I-90.
Quote from: SEWIGuy on August 02, 2010, 12:25:42 PM
I believe that the exit numbers on interstate multiplexes should use the mileage of the lowered number interestate.
If that is correct, when I-39 was extended over I-90 and I-90/94 in Wisconsin, WIDOT didn't change the interstate exit numbers to reflect I-39's mileage. They still use I-90s numbers.
Mississippi uses I-59's mileage when they're multiplexed with I-20 in the Meridian/Lauderdale County area.
^^^
Is there any rule for which set of exit numbers to use on a multiplex?
I've really never seen a pattern, but that doesn't mean there's no rule.
Quote from: mightyace on August 02, 2010, 11:07:27 PM
^^^
Is there any rule for which set of exit numbers to use on a multiplex?
I've really never seen a pattern, but that doesn't mean there's no rule.
In California, I THINK it's ordered in terms of route priority (Interstate - then US - then state) with the lower-numbered route first, though there are few instances where this is truly a factor (i.e. the Route 99 concurrencies in Sacramento, the 5/10 concurrency in East Los Angeles).
I had the impression that's how the FHWA prefers it, too.
I think it has to do with whatever route is the through route there. In the case of I-77 and I-81, they use I-81's exit numbers because I-77 leaves/joins the highway on both ends.
Quote from: rickmastfan67 on August 03, 2010, 07:20:11 PM
I think it has to do with whatever route is the through route there. In the case of I-77 and I-81, they use I-81's exit numbers because I-77 leaves/joins the highway on both ends.
But on I-35/40, I-35 numbers take precedence, when I-40 is the "through route".
Quote from: rickmastfan67 on August 03, 2010, 07:20:11 PM
I think it has to do with whatever route is the through route there. In the case of I-77 and I-81, they use I-81's exit numbers because I-77 leaves/joins the highway on both ends.
And sometimes it's which ever was there first. I-96/I-69 in Lansing, MI has I-96 milemarkers and exit numbers. I-69 came some 30 years later.
Quote from: TheStranger on August 03, 2010, 03:05:45 AM
In California, I THINK it's ordered in terms of route priority (Interstate - then US - then state) with the lower-numbered route first, though there are few instances where this is truly a factor (i.e. the Route 99 concurrencies in Sacramento, the 5/10 concurrency in East Los Angeles).
Actually, it's based upon the true route number on that particular segment. The state route definitions in California do not include route concurrencies, regardless of how the roadway may be signed.
Quote from: mapman on August 12, 2010, 12:33:23 AM
Quote from: TheStranger on August 03, 2010, 03:05:45 AM
In California, I THINK it's ordered in terms of route priority (Interstate - then US - then state) with the lower-numbered route first, though there are few instances where this is truly a factor (i.e. the Route 99 concurrencies in Sacramento, the 5/10 concurrency in East Los Angeles).
Actually, it's based upon the true route number on that particular segment. The state route definitions in California do not include route concurrencies, regardless of how the roadway may be signed.
On the surface, I'd agree - I do however recall the Calnexus website giving the explanation of route priority/lowest digit.
5/10, 99/5, Business 80/50/99, 580/80, 215/60, and 405/22 I think are the only significant freeway/freeway concurrencies left in California, at least at the present time.
Business 80 and US 50 represents the only example of two different routes sharing a set of exit numbers (from I-80 east to the Oak Park Interchange), with Business 80/hidden Route 51 continuing on with Exit 7 as well as US 50.
Quote from: JimNew York uses N-S and E-W suffixes (as opposed to A-B) in cases where more than one ramp serves the same "Exit". I don't recall seeing that practice in any other state but I don't know if it's unique to New York.
I know of 2 cases where this format is used in Vermont. One is on I-91 at I-89 (Exit 10N-S). The other is on I-89 at US 2 in Burlington (Exit 14E-W). Coincidentally, I believe these (and I-93 at I-91, but that's unnumbered) are the only multi-exit interchanges in the state, though that will change when the northeast quadrant of the Bennington bypass opens.
On a related note, the interchanges on both I-89 and I-93 at I-91 are unnumbered. I-89 would/should be Exit 1A-B regardless of whether a sequential-based or mile-based system is used. I-93 would/should be Exit 2A-B with a sequential-system and Exit 11A-B with a mile-based system.