Concurrencies with mainline interstates (1 and 2 digit interstates) and 3 digit

[ND6677]

I am curious about what are all the concurrencies with mainline interstates and 3 digit interstates. I am also wondering about all the concurrencies with a parent and child interstate route.

All I know is:
I-495 and I-95 in the DC area
I-580 and I-80 in California
I-287 and I-87 in New York
I-435 and I-29 in Kansas City
I-680 and I-29 in the Omaha area (Now gone)

[TheStranger]

I-75 and I-640 in Knoxville
I-74 and I-275 near Cincinnati
I-74 and I-465 in Indianapolis
I-69 and I-465 (future) in Indianapolis
I-294 and I-80 near Calumet, Illinois

[JayhawkCO]

I think this is a complete list. Parent/Child multiplexes bolded:

I-80/I-580 in California
I-95/I-495 in DC, Maryland, and Virginia
I-74/I-280 in Illinois
I-80/I-294 in Illinois
I-74/I-465 in Indiana
I-83/I-695 in Maryland
I-96/I-275 in Michigan
I-35E/I-694 in Minnesota
I-94/I-694 in Minnesota
I-29/I-435 in Missouri
I-87/I-287 in New York
I-26/I-240 in North Carolina (not official, but de facto)
I-73/I-840 in North Carolina
I-87/I-440 in North Carolina
I-74/I-275 in Ohio
I-84/I-380 in Pennsylvania
I-75/I-640 in Tennessee
I-35/I-410 in Texas
I-41/I-894 in Wisconsin
I-43/I-894 in Wisconsin

[Mapmikey]

It's I-73 and I-840 in Greensboro

[JayhawkCO]

It's I-73 and I-840 in Greensboro

Thanks. Fixed the typo.

[Jim]

For those who want to poke around with Interstate concurrencies, you can load up METAL's "intersection-only" graph of all US interstates generated from Travel Mapping data with this link:

https://courses.teresco.org/metal/hdx/?load=usai-system-intonly.tmg&gv=jan2024&av=none

then press "Visualize".  Pan and zoom around, and you'll see different colors, which represent the number of routes in the dataset (in this case, restricted only to US Interstates) that are concurrent along each segment.  Click on a segment to see what those routes are.  Most are 2di to 2di, so not relevant to this thread, but you should be able to find all of ones mentioned here.

Note: the intersection-only graphs are generated a few times a year, most recently in January 2024, so this graph is based on TM data from January.  The intersection-only graphs only include junctions with other routes in the system and endpoints, so they're a lot smaller than the full graphs, but perfect for this kind of thing.  HDX wouldn't be capable of loading the full 18,000+ vertex interstate graph on most browsers.

[froggie]

Missed from Jayhawk's list:  I-83/I-695 near Baltimore.

[JayhawkCO]

Missed from Jayhawk's list:  I-83/I-695 near Baltimore.

Added. Thanks. I missed it since they don't have an exit as a concurrent route (other than to split again).

[Henry]

Although they don't exactly share the same alignment, I-85 and I-285 near the Atlanta airport certainly qualify. The former uses the inner carriageways, and the later uses the outer ones.

[CtrlAltDel]

For those who want to poke around with Interstate concurrencies, you can load up METAL's "intersection-only" graph of all US interstates generated from Travel Mapping data with this link:

https://courses.teresco.org/metal/hdx/?load=usai-system-intonly.tmg&gv=jan2024&av=none

This is absolutely amazing. Thanks for posting about it.

Is there perchance something similar for US routes as well?

ETA: On a lark, I replaced "usai" in the web address with "usaus" and that seems to have worked.

[JayhawkCO]

Although they don't exactly share the same alignment, I-85 and I-285 near the Atlanta airport certainly qualify. The former uses the inner carriageways, and the later uses the outer ones.

Eh. If they don't use the same lanes, then they're not the same highway to me. Frontage roads aren't part of a highway even though they're parallel.

[froggie]

^ In that vein, and I missed this earlier, you also have I-35E/I-694 in Minnesota.

[Jim]

This is absolutely amazing. Thanks for posting about it.

Is there perchance something similar for US routes as well?

Glad you like it.  Use the "New Graph" button and you can load all kinds of stuff this way.  The HDX viewer (more accurately, the Leaflet map it uses) gets overwhelmed and either doesn't load or gets ridiculously slow over maybe about 7,000 vertices and edges.  You can see a lot more systems and regions by picking the intersection-only graphs, which are the smaller ones with the same names when you are using Advanced Search and choose a graph archive set (like January 2024).  All this reminds me I'm way overdue for a new archive set.

[SEWIGuy]

I think this is a complete list. Parent/Child multiplexes bolded:

I-80/I-580 in California
I-95/I-495 in DC, Maryland, and Virginia
I-80/I-294 in Illinois
I-74/I-465 in Indiana
I-83/I-695 in Maryland
I-96/I-275 in Michigan
I-94/I-694 in Minnesota
I-29/I-435 in Missouri
I-87/I-287 in New York
I-26/I-240 in North Carolina (not official, but de facto)
I-73/I-840 in North Carolina
I-87/I-440 in North Carolina
I-74/I-275 in Ohio
I-84/I-380 in Pennsylvania
I-75/I-640 in Tennessee
I-35/I-410 in Texas
I-41/I-894 in Wisconsin
I-43/I-894 in Wisconsin

I-74/I-280 in Illinois

[JayhawkCO]

I think this is a complete list. Parent/Child multiplexes bolded:

I-80/I-580 in California
I-95/I-495 in DC, Maryland, and Virginia
I-80/I-294 in Illinois
I-74/I-465 in Indiana
I-83/I-695 in Maryland
I-96/I-275 in Michigan
I-94/I-694 in Minnesota
I-29/I-435 in Missouri
I-87/I-287 in New York
I-26/I-240 in North Carolina (not official, but de facto)
I-73/I-840 in North Carolina
I-87/I-440 in North Carolina
I-74/I-275 in Ohio
I-84/I-380 in Pennsylvania
I-75/I-640 in Tennessee
I-35/I-410 in Texas
I-41/I-894 in Wisconsin
I-43/I-894 in Wisconsin

I-74/I-280 in Illinois

Missed from Jayhawk's list:  I-83/I-695 near Baltimore.

Added. Thanks. I missed it since they don't have an exit as a concurrent route (other than to split again).

Ditto. Thanks.

[freebrickproductions]

I-40 and I-240 and also I-69* and I-240 in Memphis, TN.

(*In the future, at least.)

[JayhawkCO]

I-40 and I-240 and also I-69* and I-240 in Memphis, TN.

(*In the future, at least.)

I-40/I-240 is similar to the I-49/I-470 one I had posted and deleted. It's more of a long-distance interchange than it is a concurrency.

[Great Lakes Roads]

Soon-to-be-added onto the list: I-69/I-465 and I-69/I-74/I-465 in Indianapolis

[bugo]

I-44/240 in OKC
Future I-42/I-244 in Tulsa