Interchanges between freeways in which both freeways' exit numbers differ by one

[KCRoadFan]

For me, this is post number 470, which makes it appropriate for me to make a thread inspired by the freeway of the same number in my metro area.

To be precise: in Independence, MO, just east of KC, the interchange between I-70 and I-470 is marked as Exit 15 (A-B) on I-70 and Exit 16 (B-C) on I-470. That made me wonder: where else throughout the country might there be interchanges between two freeways, in which the exit numbers on both freeways are consecutive (that is, the exit number on one freeway is one greater or less than the exit number on the other freeway)?

[SkyPesos]

I-80 (exit 68) at its eastern terminus with I-95 (exit 69).

And keeping the 470 theme, though no exit number is listed, I-470 in WV meets I-70 (exit 5A) at milepost 4.

[Bruce]

I-90 (exit 10) at I-405 (exit 11) in Bellevue, WA fits the bill.

[jmacswimmer]

I-97 (exit 14) & MD 100 (exit 13) just southeast of BWI.  When arrivals are on runway 33L (which is most of the time during ideal weather), you get a great view of this interchange roughly 10 seconds before touchdown so long as you're sitting on the right side of the plane.

[NWI_Irish96]

I-65 at I-265 in Jeffersonville/Clarksville is Exit 6 for I-65 and Exit 7 for I-265.

[GaryA]

Differs by 2, but the way it ended up seems like it could be confusing.

In Moorpark, CA, the freeway changes from NB CA 23 to EB CA 118 (both routes exit to the same surface street, and split up a little later).  This is exit 20 on CA 23, and exit 18 on CA 118.

So the exit numbers, if you start on NB CA 23 and continue on the freeway, are 17, 19, 20A/B (route number switch), 19A, 19B, 22.  If you start on WB CA 118 and stay on the freeway, you see 22, 19B, 19A, 18B/A (route number switch), 19, 17.

I'm not sure how label TOTSO interchanges *should* be labelled, here it looks like they are calling both the ramp and the freeway "exits", so northbound the ramp is Exit 20A and the freeway is Exit 20B.

[jp the roadgeek]

Used to be that I-90 (Mass Pike) and I-291 were Exit 6 on both roads, but exit renumbering changed that for I-90.


I-80 and I-287 in NJ are off by 2 (43 and 41, respectively).  When CT is renumbered, I-84 and CT 8 will be off by 2 (32 and 30), as will I-91 and CT 9 (27 and 29)

If the I-80 eastern termini had numbers, I-95 would be 68, while I-80 is Exit 69 on 95.

[WNYroadgeek]

The only New York example I can think of: (Free) I-90 (Exit 6A) and I-787 (Exit 5) in Albany.

[ran4sh]

Differs by 2, but the way it ended up seems like it could be confusing.

In Moorpark, CA, the freeway changes from NB CA 23 to EB CA 118 (both routes exit to the same surface street, and split up a little later).  This is exit 20 on CA 23, and exit 18 on CA 118.

So the exit numbers, if you start on NB CA 23 and continue on the freeway, are 17, 19, 20A/B (route number switch), 19A, 19B, 22.  If you start on WB CA 118 and stay on the freeway, you see 22, 19B, 19A, 18B/A (route number switch), 19, 17.

I'm not sure how label TOTSO interchanges *should* be labelled, here it looks like they are calling both the ramp and the freeway "exits", so northbound the ramp is Exit 20A and the freeway is Exit 20B.

The MUTCD doesn't go into detail, but it seems that what they call for is to ignore the engineering definition of "exit" and use the route designations as the determination of an "exit". In your case that would mean not assigning an exit number to the exit ramps that the route follows, but instead assigning an exit number to the freeway mainline because it changes route number despite being engineered as the thru route.

[PurdueBill]

Exit 17 on OH 8 is for I-271; exit 18 on 271 is for OH 8. 

[Dirt Roads]

Differs by 2, but the way it ended up seems like it could be confusing.

In Moorpark, CA, the freeway changes from NB CA 23 to EB CA 118 (both routes exit to the same surface street, and split up a little later).  This is exit 20 on CA 23, and exit 18 on CA 118.

So the exit numbers, if you start on NB CA 23 and continue on the freeway, are 17, 19, 20A/B (route number switch), 19A, 19B, 22.  If you start on WB CA 118 and stay on the freeway, you see 22, 19B, 19A, 18B/A (route number switch), 19, 17.

I'm not sure how label TOTSO interchanges *should* be labelled, here it looks like they are calling both the ramp and the freeway "exits", so northbound the ramp is Exit 20A and the freeway is Exit 20B.

The MUTCD doesn't go into detail, but it seems that what they call for is to ignore the engineering definition of "exit" and use the route designations as the determination of an "exit". In your case that would mean not assigning an exit number to the exit ramps that the route follows, but instead assigning an exit number to the freeway mainline because it changes route number despite being engineered as the thru route.

NCDOT does that here in North Carolina, and it is now prevalent on many of the Interstates.  I-40 Eastbound in Raleigh is Exit 301 off of the Beltline, with the through route being I-440 Westbound and I-87 Northbound.  There are also the two examples on I-40 both east and west of Greensboro, after the route was moved back onto the original Death Valley route after the southern part of the Greensboro Urban Loop was designed to be the through route.  (I still like to use I-40 through Death Valley in the off-peak, even though the southern Loop is only a few miles longer and sometimes faster).  Pretty sure there are many more examples here.

[Dirt Roads]

Before I forget: Exit 6 on I-195 in New Jersey, Exit 7A on the New Jersey Turnpike.

[jp the roadgeek]

The LIE and Cross Island Parkway.  I-495 Exit 31 N/S and Cross Island Exit 30 E/W

[Roadsguy]

The interchange between I-70 and PA Turnpike 43/Mon Fayette Expressway in southwest Pennsylvania is Exit 36 on PA 43 and Exit 37 on I-70. This is, to my knowledge, the only example in Pennsylvania. It wasn't even difficult to check every freeway-to-freeway interchange with numbered exits on more than one road, since PennDOT doesn't number exits on most non-Interstates.

[Dirt Roads]

The interchange between I-70 and PA Turnpike 43/Mon Fayette Expressway in southwest Pennsylvania is Exit 36 on PA 43 and Exit 37 on I-70. This is, to my knowledge, the only example in Pennsylvania. It wasn't even difficult to check every freeway-to-freeway interchange with numbered exits on more than one road, since PennDOT doesn't number exits on most non-Interstates.

Under the almost category, is the one in Allentown that doesn't exist.  On the Northeast Extension (I-476), Old Exit 33 is near MM 56 and on I-78, Old Exit 15 is near MM 51.  Then there is New Exit 53 (PA-308 Split) on I-78.  But the two freeways cross each other where the mile markers are even closer to each other.