Even numbered 3-digit interstates

[Konza]

Radial/circumferential is my preference, but there are still a few problems, like I-355 in Illinois, which I feel is a correct odd number contrary to my preference.

At the risk of this being a Fictional Highways thread, let's do a couple of things here:

• Let's build the Illinois 53 extension through Lake County and connect it to US 12 at the Cheddar Curtain.
  Let's extend I-355 south (Illiana Expressway or some mutation of it) and bend it east at least as far as I-65.
  Let's call the entire route I-355.
  

So we'd now have another beltway around most of the Chicago area, but it would never cross a mainline Interstate twice.

Theoretically, working from the north, it could start at I-43 near Lake Geneva
It would cross I-90 at Schaumburg and I-88 near Downers Grove
It would cross I-55 and I-80 where it currently intersects them.
And it would cross I-57 and terminate at I-65

From none of these seven routes could you exit onto this highway and have a reasonable expectation that you would be reunited with the route you just left.

That's why it is (and would be) properly signed as an odd first digit 3di.

[kphoger]

I-880 is technically a spur that ... connects to another interstate ...

If it connects two Interstates, then it isn't a spur.  That's not what "spur" means.

[Great Lakes Roads]

Okay, here we go with Indiana's three-digit interstates.

I-265: Currently connects I-64 and I-65 in the Louisville metro area and will be extended east to the Ohio River to form a 3/4 beltway around Louisville.
I-465: Beltway around Indianapolis.
I-865: Formerly a dogleg of Interstate 465, it was changed in 2002 to avoid the confusion. Connects I-65 in the northward direction (to/from Chicago) to I-465.
I-469: Partial beltway around the eastern side of Fort Wayne. Connects to I-69 on both ends.
I-275: Beltway around Cincinnati with I-275 serving three miles of Indiana which its parent route, I-75, does not go to.

No, we are not going to talk about I-164 which is now absorb into I-69.

[ilpt4u]

Okay, here we go with Indiana's three-digit interstates.

I-265: Currently connects I-64 and I-65 in the Louisville metro area and will be extended east to the Ohio River to form a 3/4 beltway around Louisville.
I-465: Beltway around Indianapolis.
I-865: Formerly a dogleg of Interstate 465, it was changed in 2002 to avoid the confusion. Connects I-65 in the northward direction (to/from Chicago) to I-465.
I-469: Partial beltway around the eastern side of Fort Wayne. Connects to I-69 on both ends.
I-275: Beltway around Cincinnati with I-275 serving three miles of Indiana which its parent route, I-75, does not go to.

No, we are not going to talk about I-164 which is now absorb into I-69.

AASHTO in the Spring 2019 session approved the Unified I-265 in IN/KY for the 3/4 bi-state Louisville Beltway. InDOT and KYTC haven't yet signed it, but it now is an approved designation

865 would have been a better 765, especially if a Western Extension to I-74 ever comes to pass imho, but probably too late on that

[ilpt4u]

From none of these seven routes could you exit onto this highway and have a reasonable expectation that you would be reunited with the route you just left.

That's why it is (and would be) properly signed as an odd first digit 3di.

So whats your take on the extended "candy cane"  or "j hook"  I-295 in Delaware/NJ/PA since the new I-95/PA Turnpike interchange and routing?

Traffic from either endpoint defaults onto I-95 South...there is no movement to (directly) utilize I-295 as an I-95 Bypass...used in combination with NJ I-195, yes.

Also is I-295 and I-95 in NJ the only place a Parent crosses its Child/Aux route with no Interchange? That would be the Logical place to put a full Interchange to utilize I-295 as a Bypass/Alternate to I-95...but it would also make shunpiking the southern NJ Turnpike much easier

[Konza]

From none of these seven routes could you exit onto this highway and have a reasonable expectation that you would be reunited with the route you just left.

That's why it is (and would be) properly signed as an odd first digit 3di.

So whats your take on the extended "candy cane"  or "j hook"  I-295 in Delaware/NJ/PA since the new I-95/PA Turnpike interchange and routing?

Traffic from either endpoint defaults onto I-95 South...there is no movement to (directly) utilize I-295 as an I-95 Bypass...used in combination with NJ I-195, yes.

Also is I-295 and I-95 in NJ the only place a Parent crosses its Child/Aux route with no Interchange? That would be the Logical place to put a full Interchange to utilize I-295 as a Bypass/Alternate to I-95...but it would also make shunpiking the southern NJ Turnpike much easier

It certainly appears that I-295 was always intended to be an alternate route from Delaware to northern New Jersey.  The connections at the north end are clumsy at best, and at least part of the route was built when I-95 was planned to follow a new terrain route north of Trenton.  The northern section is a loop around Trenton and might benefit from a different route number but connects with the parent route at both ends, even if you have to use I-195 to make the connection.

When you take the ramp onto I-295, you have a reasonable expectation that you will be routed back to the parent route.  I'd add that, in my I-355 example, if the beltway were to be extended east of I-65 to connect with I-80/90 in Indiana, I would support an even first digit 3di route number (I-X90?) for the section of the road between Schaumburg and that eastern connection.

[PHLBOS]

So whats your take on the extended "candy cane"  or "j hook"  I-295 in Delaware/NJ/PA since the new I-95/PA Turnpike interchange and routing?

Traffic from either endpoint defaults onto I-95 South...there is no movement to (directly) utilize I-295 as an I-95 Bypass...used in combination with NJ I-195, yes.

Also is I-295 and I-95 in NJ the only place a Parent crosses its Child/Aux route with no Interchange? That would be the Logical place to put a full Interchange to utilize I-295 as a Bypass/Alternate to I-95...but it would also make shunpiking the southern NJ Turnpike much easier.

It certainly appears that I-295 was always intended to be an alternate route from Delaware to northern New Jersey.  The connections at the north end are clumsy at best, and at least part of the route was built when I-95 was planned to follow a new terrain route north of Trenton.  The northern section is a loop around Trenton and might benefit from a different route number but connects with the parent route at both ends, even if you have to use I-195 to make the connection.

Regarding I-295 in the Delaware Valley, there's a couple things to keep in mind.

1.  As you previously mentioned, the northern end of I-295 in NJ was originally where the Somerset Freeway (I-95 north of Trenton) would've been constructed.

2.  There are still long-term plans to add the remaining missing moves at the I-95/276/295 interchange in Bristol, PA.  Once the I-295 to I-95 northbound and the I-95 southbound to I-295 ramps are built; one can theoretically go from I-295 northbound/westbound to I-95 northbound and/or go from I-95 southbound to I-295 eastbound/southbound... although such a move would not be desirable for long-distance traffic.

When you take the ramp onto I-295, you have a reasonable expectation that you will be routed back to the parent route.

I-276 in PA says otherwise.

[Mergingtraffic]

I still read it as, as long as an 3di meets an interstate at both ends it should be an even 3di.

CT has I-395 which connects I-95 at it southern end and I-290/I-90 at it's northern end in MA.  I think I-290 should replace I-395. It's not a spur, it connects two different interstates.

[hotdogPi]

I still read it as, as long as an 3di meets an interstate at both ends it should be an even 3di.

CT has I-395 which connects I-95 at it southern end and I-290/I-90 at it's northern end in MA.  I think I-290 should replace I-395. It's not a spur, it connects two different interstates.

What would it be a loop around?

[kurumi]

I still read it as, as long as an 3di meets an interstate at both ends it should be an even 3di.

CT has I-395 which connects I-95 at it southern end and I-290/I-90 at it's northern end in MA.  I think I-290 should replace I-395. It's not a spur, it connects two different interstates.

It looked like it was going to be part of I-290 (in official statements and newspaper articles) until a few weeks before it was designated as I-395: https://www.kurumi.com/roads/ct/i290.html

[cjk374]

Ideally, an even number should be used when the roadway is linking two interstate highways, whether it be the same interstate highway at either end (I.E. a beltway, bypass, etc.), or another interstate highway (I.E. a connector).

The 2nd half of this statement applies to I-220 in Jackson, MS. Connects I-20 on the west side of Jackson (Clinton, MS) to I-55 on the north side of Jackson (near Ridgeland).

[Revive 755]

I still read it as, as long as an 3di meets an interstate at both ends it should be an even 3di.

CT has I-395 which connects I-95 at it southern end and I-290/I-90 at it's northern end in MA.  I think I-290 should replace I-395. It's not a spur, it connects two different interstates.

What would it be a loop around?

The State of Rhode Island - although this would call for making it I-695 or I-895.

Or going further into fictional territory - make it a reroute of I-495, with existing I-495 south of existing I-290 becoming I-395.

[TEG24601]

This could easily be fixed by removing the prefix digit, and instead use a suffix digit indicating direction, with 5 and 0 being reserved for beltways, but not partial loops.


This would make the new I-880, I-802.  I-680 in Omaha would become, in theory, I-809.

[Flint1979]

but it's also almost perfectly a straight line (which means odd).

Counterpoint: I-475 (GA) is nearly a straight line, but wouldn't make any sense at all with an odd first digit.

That highway connects to I-75 on both ends. And it is the route to take for long distance travel.

[triplemultiplex]

This would make the new I-880, I-802.  I-680 in Omaha would become, in theory, I-809.

I have mused that this would be a reasonable convention for numbering auxillary routes of an interstate 100, 200, 300, etc.

There could be an I-104 in Florida that's a spur, but then there could be an I-104 in some other state that's a loop.

The rationale would be to free up unique numbers in the eastern third of the country for mainline interstates.  It would have to be an O.G. part of the system though; you're not going to come in today and do it. But it makes for some fun fictional musings.

I pick angling interstate corridors that get out of the grid and slot in one of these 100 interstates.  Like a combined I-81/I-78 corridor from eastern TN to NYC.  Make it I-100.  That frees 78 and either 81 or 83 because they become one corridor from Baltimore to Canada.  Now I've got two numbers I can plug in elsewhere.

[Flint1979]

I think that I 196 is numbered the way it is because it was originally the spur route to Muskegon and I-96 was supposed to go to Benton Harbor so with the number swap it ended up where it is now

[kurumi]

This could easily be fixed by removing the prefix digit, and instead use a suffix digit indicating direction, with 5 and 0 being reserved for beltways, but not partial loops.

This would make the new I-880, I-802.  I-680 in Omaha would become, in theory, I-809.

In California, the x80s could follow the same convention and not conflict with state routes e.g. CA 180. But... I-5. Its auxiliary routes would be either "2-digit" routes (51, 52, etc.) or a weird leading zero convention (051, 052). And a bunch of state routes are in the way.

[Eth]

But... I-5. Its auxiliary routes would be either "2-digit" routes (51, 52, etc.) or a weird leading zero convention (051, 052). And a bunch of state routes are in the way.

You could go with 501, 502, etc., though I guess that has the minor drawback that I-8 and I-80 would have to share the same pool.

[TheGrassGuy]

Hmmm, let's see how it is for I-95.
I-195 in ME connects to I-95 at one end
I-395 in ME connects to I-95 at one end
I-195 in NJ connects to I-295 at one end
I-395 in MD connects to I-95 at one end
I-795 in MD connects to I-695 at one end
I-395 in DC-VA connects to I-95/495 at one end
I-195 in VA connects to I-95 at one end
I-795 in NC connects to I-95 at one end
I-195 in FL connects to I-95 at one end
I-395 in FL connects to I-95 at one end

I-295 in ME connects to I-95 at both ends
I-495 in ME connects I-95 and I-295
I-295 in MA and RI connects to I-95 at both ends
I-495 in MA connects to I-95 at both ends
I-695 in NY connects I-95 and I-295
I-295 in NJ, PA, and DE connects to I-95 at both ends (even before the golden spike)
I-495 in DE connects to I-95 at both ends
I-295 in MD and VA connects I-95/495 and I-695
I-495 in MD, DC, and VA is a beltway
I-695 in MD is a beltway
I-895 in MD connects to I-95 at both ends
I-695 in DC connects I-395 and I-295
I-295 in VA connects I-95 and I-64
I-295 in FL is a beltway

I-195 in MA and RI connects I-95 and I-495
I-395 in CT and MA connects I-95 and I-90/I-290
I-195 in MD connects to I-95 in the middle, but neither of its termini are at interstates
I-595 in MD connects to I-95/495 in the middle, but neither of its termini are at interstates
I-595 in FL connects to I-95 in the middle, but neither of its termini are at interstates

I-295 in NY connects to I-95 at one end (though not if it were built as planned)
I-495 in NY connects to I-295 in the middle, but neither of its termini are at interstates

[Beltway]

I-595 in MD connects to I-95/495 in the middle, but neither of its termini are at interstates

MD I-595 (unposted) follows US-50 and connects I-495/I-95 to MD-70.

It doesn't go west of I-495/I-95.

[TheGrassGuy]

I-595 in MD connects to I-95/495 in the middle, but neither of its termini are at interstates

MD I-595 (unposted) follows US-50 and connects I-495/I-95 to MD-70.

It doesn't go west of I-495/I-95.

Source, please? I know that the western terminus of the John Hanson Hwy is at the Baltimore-Washington Pkwy, but that's not an interstate.

[Beltway]

I-595 in MD connects to I-95/495 in the middle, but neither of its termini are at interstates

MD I-595 (unposted) follows US-50 and connects I-495/I-95 to MD-70.
It doesn't go west of I-495/I-95.

Source, please? I know that the western terminus of the John Hanson Hwy is at the Baltimore-Washington Pkwy, but that's not an interstate.

I-595 in Maryland is the longest unsigned route within the Interstate Highway System.  Aligned entirely along U.S. 50 (John Hanson Highway) and partially along U.S. 301, the I-595 designation applies to the freeway between I-95/495 (Capital Beltway) and Maryland 70 at Annapolis.
https://www.interstate-guide.com/i-595-md/

Interstate 595 lines 19.97 miles of the U.S. 50 freeway (John Hanson Highway) between the Capital Beltway (Interstates 95 & 495) and the interchange with Maryland 70 (Rowe Boulevard) at Annapolis.  This stretch of U.S. 50 was designated as an Interstate in 1989.
https://www.aaroads.com/guides/i-595-md/

The segment of US-50 from I-495 to Annapolis was approved for Interstate construction as I-68.
US-50 from I-495/I-95 to MD-70 was reconstructed to six-lane Interstate standards from 1990 to 1995.  All the interchanges were reconstructed also, including the new full semi-directional interchange between US-50 and the Capital Beltway (I-95/I-495).
When the National Freeway in Western Maryland was completed in 1991, it was given the I-68 designation, and US-50 (I-495 Capital Beltway to MD-70 Roscoe Rowe Blvd.) was authorized to receive the I-595 designation, an Interstate spur from I-95 to Annapolis.
http://www.roadstothefuture.com/I595_MD.html

The US-50 freeway west of the Beltway has not had an Interstate designation.

[PHLBOS]

I-495 in MA connects to I-95 at both ends

Prior to the southern extension opening circa 1982, such was true.  Since then, the southern end of I-495 in MA is at I-195/MA 25.

[X99]

865 would have been a better 765, especially if a Western Extension to I-74 ever comes to pass imho, but probably too late on that

I proposed that once on a Fictional Highways thread and most of the responses said it would be redundant.

[JMoses24]

It could go either way for 880. It's circumferential, not radial, with regard to Omaha (which means even), but it's also almost perfectly a straight line (which means odd).

There is a tendency for even digit numbered routes to connect back to their parent but out here in California that trend is non-existent.   A good example is the I-80 family of highways in California:

-  I-280 doesn't even connect to it's parent but does by proxy to I-880 and I-680
-  I-480 connected to it's parent but didn't loop back to it.
-  Likewise I-680 and I-880 touch their parent route I-80 but definitely aren't loops. 

Interestingly though I-405 and I-805 do loop to/from I-5 whereas none of the odd number child routes do.  I-215 does loop to I-15 but that route was intended to be I-15E.

And I-215 goes way out of its way in doing so, curving easterly on CA 60. If you want a more straightforward route back to I-15 out of Riverside, you'd use 91 to meet 15 in Corona.

As for I-605, if it didn't connect to the 405 on the south to return to I-5, that would need to be 705 or 305.

Hell, I-105 doesn't connect to its parent route at all except by using I-605 north to I-5. It was originally meant to but Caltrans figured the 5 couldn't handle it, not to mention the prevalent NIMBY's of the time revolted against it.