Mile markers for concurrencies

[mcdonaat]

I noticed a while back that MacArthur Drive in Alexandria has "Exit 70" for LA 1, but the route is a concurrency of US 71/US 165/LA 28. Is there some rule that governs which highway is actually designated by the mileage?

Most traffic to the north uses US 165, while most traffic to the south uses US 71, so the true designation of a through route is null. The same can be questioned on LA 3225 just north of Pineville, aka the old US 71/167, where mile markers are in place, but following the mileage of the former route, whether the route was US 71 or US 167.

[roadfro]

Generally speaking, the mileposting (and distance-based exit numbering) follows the route of the highest order precedence. For example, in a hypothetical overlap between I-50 and US 55, the highway would use the mileposts of I-50. In the case of two equal-status routes overlapping, it's the lower number route that is dominant for mileposting--for the US 71 & US 165 overlap mentioned above, US 71 would typically be the route mileposted.

There are exceptions to this. For example, on the I-515/US 93/US 95 overlap through Las Vegas, it is US 95 that controls for mileposts and exit numbers--this is because US 95 is the through route on the freeway where US 93 turns off to follow I-15, and both highways existed on this alignment many years before I-515 was designated and signed. (An interesting note is that the same overlap is inventoried internally by NDOT as I-515, even though mileposted as US 95.)

[pianocello]

History and maintenance might also be a factor. For example, the multiplex between I-80 and I-294 in Chicagoland uses Tri-State mileage because it's maintained by the ISTHA. Also, the 69/96 multiplex near Lansing, MI uses 96 mileage because 96 was there for almost 25 years before 69 existed.

[Dr Frankenstein]

On the other hand, one could use "enhanced" mile markers to post the mileage of both routes. I think I've seen this before.

[Henry]

Generally speaking, the mileposting (and distance-based exit numbering) follows the route of the highest order precedence. For example, in a hypothetical overlap between I-50 and US 55, the highway would use the mileposts of I-50. In the case of two equal-status routes overlapping, it's the lower number route that is dominant for mileposting--for the US 71 & US 165 overlap mentioned above, US 71 would typically be the route mileposted.

There are exceptions to this. For example, on the I-515/US 93/US 95 overlap through Las Vegas, it is US 95 that controls for mileposts and exit numbers--this is because US 95 is the through route on the freeway where US 93 turns off to follow I-15, and both highways existed on this alignment many years before I-515 was designated and signed. (An interesting note is that the same overlap is inventoried internally by NDOT as I-515, even though mileposted as US 95.)

History and maintenance might also be a factor. For example, the multiplex between I-80 and I-294 in Chicagoland uses Tri-State mileage because it's maintained by the ISTHA. Also, the 69/96 multiplex near Lansing, MI uses 96 mileage because 96 was there for almost 25 years before 69 existed.

And there's also the I-40/I-85 multiplex in NC, which for many years had only I-85 signed on it because I-40 ended in Greensboro. Even when the I-40 extension was completed in 1989, the I-85 mileage and exit numbers were kept because I-85 was there first.

[bassoon1986]

Generally speaking, the mileposting (and distance-based exit numbering) follows the route of the highest order precedence. For example, in a hypothetical overlap between I-50 and US 55, the highway would use the mileposts of I-50. In the case of two equal-status routes overlapping, it's the lower number route that is dominant for mileposting--for the US 71 & US 165 overlap mentioned above, US 71 would typically be the route mileposted.

And that's the case here. That exit is number 70, exits for I-49 are 71A and B and exits for I-49 on the south end of town are 63. US 71 ends 63 miles south of there

[Special K]

In Iowa, the order of precedence of equal-level routes goes to the longer of the two.  For example, I-35 and I-80 join at West Des Moines and run concurrently around the west and north of the Des Moines metro.  Reference posts in this run follow I-80's numbering.

[hbelkins]

On the other hand, one could use "enhanced" mile markers to post the mileage of both routes. I think I've seen this before.

US 13 and US 50 at Salisbury, Md.

[Dr Frankenstein]

Yeah, that must be where I saw that, I was there in August.

[Henry]

On the other hand, one could use "enhanced" mile markers to post the mileage of both routes. I think I've seen this before.

US 13 and US 50 at Salisbury, Md.

Hmmm...I'd love to see a photo of that!

[hbelkins]

http://www.millenniumhwy.net/2010_SEPA_Day_2/Pages/602.html
http://www.millenniumhwy.net/2010_SEPA_Day_2/Pages/603.html

[Quillz]

I was wondering this, myself. There are a few concurrencies in California and it seems to follow the same general idea: preference given to the route of the higher magnitude, followed by lower number (in the event routes are equal magnitude).

However, what I'm not clear on is how suffixes are handled. For example, I believe Texas uses I-35's overall mileage on I-35E, while I-35W has its own mile markers. The former is a bit longer than the latter, and my guess, then, is I-35E existed first (at least on paper), or the longer route continues the mainline's mileage. Is this also the case in Minnesota? How is mileage going to be handled on the three splits of I-69? Seems to me that all suffixes should have their own mile markers, and the mainlines would simply pick up at a later point, as if there was a gap in the route. (Although this is only relevant to suffixes that would form loops.)

[noelbotevera]

PA does enhanced mile markers (like what hbelkins posted), but screws them up. Near I-81, where the multiplex ends, you start getting mile 199.1. It has a US 22 shield. At mile 199.2, there's now a US 322 shield. It switches shields up until mile 200, when you figure out that that was US 22's mileage. US 22 was well before US 322, meaning that the mile markers were kept for US 22.

[PHLBOS]

In Burlington, MA along I-95/US 3; US 3 mile markers (including both old & new MM 71) are posted along the CD road at the US 3 North/Middlesex Turnpike (Exits 32A-B) interchange.

[TheHighwayMan3561]

However, what I'm not clear on is how suffixes are handled. For example, I believe Texas uses I-35's overall mileage on I-35E, while I-35W has its own mile markers. The former is a bit longer than the latter, and my guess, then, is I-35E existed first (at least on paper), or the longer route continues the mainline's mileage. Is this also the case in Minnesota?

Our I-35E carries the exit numbers and legislative route number for I-35, but I-35W is slightly longer than I-35E.

I'm not sure how Minnesota determines their identical-precedence overlaps, although I think the route maintaining the mainline generally gets the precedence. By that I mean if for example an east-west highway intersects a north-south highway and the east-west highway turns to join the N/S route on its N/S alignment, the N/S route gets the precedence.

[halork]

From another thread...

Saw this out in eastern Colorado... I don't think this is a good idea.  Just pick one.

[peterj920]

Wis 441 in the Appleton area received mile markers years ago, but the exits weren't numbered.  US 10 runs concurrent with Wis 441 for about 5 miles and 2 years ago decided to give US 10 mile markers.  Along that 5 mile stretch, there are mile markers for both US 10 and Wis 441, and the 6 exits along that stretch have US 10 exit numbers.  Past US 10, WISDOT opted not to give exit numbers for the remaining exits along Wis 441 despite having mile markers.

[bzakharin]

I was wondering about I-295's mile markers on and around the Delaware Memorial Bridge. They are "DRBA" numbers and not either NJ or Delaware. It looks like I-295's NJ mile 0 is north of Exit 1 with NJ Turnpike's mile 0 a bit further south almost directly at exit 1 (that one is actually posted) even though presumably the Turnpike has already ended by then. This is immediately followed by a "DRBA 5.16" sign. The "DRBA Mile 0.0" sign is north of the exit for I-495 in Delaware followed immediately by Delaware's "Mile 1" sign. Are there other places where the toll bridge authority has its own mile markers separate from the states on either side, and mile 0 for the state not being at the state line?

[Quillz]

From another thread...

Saw this out in eastern Colorado... I don't think this is a good idea.  Just pick one.

Actually, i don't think that's a bad idea. Though it could get excessive with more than two con currencies.

[PHLBOS]

From another thread...

Saw this out in eastern Colorado... I don't think this is a good idea.  Just pick one.

Actually, i don't think that's a bad idea. Though it could get excessive with more than two con currencies.

Such could work for the I-95 portion of the NJ Turnpike.

[mapman1071]

Generally speaking, the mileposting (and distance-based exit numbering) follows the route of the highest order precedence. For example, in a hypothetical overlap between I-50 and US 55, the highway would use the mileposts of I-50. In the case of two equal-status routes overlapping, it's the lower number route that is dominant for mileposting--for the US 71 & US 165 overlap mentioned above, US 71 would typically be the route mileposted.

There are exceptions to this. For example, on the I-515/US 93/US 95 overlap through Las Vegas, it is US 95 that controls for mileposts and exit numbers--this is because US 95 is the through route on the freeway where US 93 turns off to follow I-15, and both highways existed on this alignment many years before I-515 was designated and signed. (An interesting note is that the same overlap is inventoried internally by NDOT as I-515, even though mileposted as US 95.)

How will this work If I-515 is used as I-11.

[jeffandnicole]

From another thread...

Saw this out in eastern Colorado... I don't think this is a good idea.  Just pick one.

Actually, i don't think that's a bad idea. Though it could get excessive with more than two con currencies.

Per the 2009 MUTCD:

Section 2H.05 Reference Location Signs (D10-1 through D10-3) and Intermediate Reference Location Signs (D10-1a through D10-3a)

Support:
09 The distance numbering shall be continuous for each route within a State, except where overlaps occur (see Section 2E.31). Where routes overlap, reference location sign continuity shall be established for only one of the routes. If one of the overlapping routes is an Interstate route, that route shall be selected for continuity of distance numbering.

Especially in referencing an accident or incident, you just want one number available.  Multiple numbers invite confusion. 

[Quillz]

I see the MUTCD left it up to the states to decide which route gets the mileage markers when they are of equal stature. Anyone know any states that deviate from the lower number getting preference?

[pianocello]

I see the MUTCD left it up to the states to decide which route gets the mileage markers when they are of equal stature. Anyone know any states that deviate from the lower number getting preference?

Indiana does on their Interstates, but that's just circumstantial. I only know of 3 Interstate concurrencies:

80/94 crosses the state line together, so mileage is identical until the split
80/90 uses Toll Road mileage, which I'm sure would be the case even if I-90 wasn't signed on the entire length.
74/465 uses 465's mileage, which is probably just for continuity with the rest of the beltway.

Not sure what they do with US routes.

EDIT: Just remembered the short 65/70 multiplex, which uses I-65's numbers. This post is bunk.

[The Nature Boy]

If I were in charge of a state DOT, I would give preference to the more heavily traveled interstate as Virginia does I-95/64 in Richmond.