Topologically identical networks

[Duke87]

It has occurred to me that when the I-86 designation is eventually extended, Binghamton, NY will have an interstate network that is topologically identical to that of Charleston, WV. As such:


For Charleston, Red = I-64, Blue = I-77, Green = I-79
For Binghamton, Red = (future) I-86, Blue = I-81, Green = I-88

The topology here is fairly simple but it does make me wonder... are there any more complex examples of where two networks are topologically identical?

Note that for the sake of topology, scale does not matter, and neither does curvature or exact direction. All that matters is that both networks, when simplified into a diagram like the one above, look the same.

[empirestate]

Probably not unrelated to their river systems being similar also.

How would Pittsburgh size up in this regard?


iPhone

[tcorlandoinsavannah]

Is this the type of scenario you're looking for?

Charleston, SC = Wilmington, NC (assuming the missing link of I-140 is completed)

Charleston - I-26 comes in from the NW.  I-526 branches off in either direction from its parent.  Each end terminates at US 17 on opposite sides of town.  The parent (I-26) continues toward the city center.
Wilmington - I-40 comes in from the NW.  I-140 branches off in either direction from its parent.  Each end will terminate at US 17 on opposite sides of town.  The parent (I-40) continues toward the city center.

Admittedly, this is not a very complex example, but is it the type of thing you're looking for?

[Duke87]

Is this the type of scenario you're looking for?

Charleston, SC = Wilmington, NC (assuming the missing link of I-140 is completed)

This is not a valid example because I-140 does not (and as far as I know will not) extend north of I-40. So Charleston has this topology:


And Wilmington has this topology:


If the freeway segment of US 17 north of I-40 were to have the I-140 designation extended along it, then it would be a valid example.

Also note: the fact that both ends of the spur route end at the same US highway is not important since the example is considering purely the topology of the interstates. Although, one could run this thought experiment with US highways, state highways, or transit systems, etc. Doesn't have to be interstates.



It does occur to me, though, that Charleston SC and Savannah GA both share the same topology - 26 and 526, 16 and 516. It's a simple example geometrically but it's cool how the numbers are so similar.

[hotdogPi]

Rotation is allowed, right?

Sioux Falls, SD (I-90, I-29, I-229)
Lawrence MA (I-93, I-495, MA 213)

[hbelkins]

You don't have Charleston, WV quite right. Even if you stretch Charleston to include Beckley, I-77 is the through (straight) route.

[tidecat]

Until I-22 is complete, Birmingham and Louisville are fairly similar:

I-65:I-65
I-64:I-20/59 & I-20
I-71:I-59
I-265:I-459

The only difference is that Louisville has an extra bypass route in I-264

[tcorlandoinsavannah]

It does occur to me, though, that Charleston SC and Savannah GA both share the same topology - 26 and 526, 16 and 516. It's a simple example geometrically but it's cool how the numbers are so similar.

I agree; I always found that interesting.  Also, both 3di's cross over the parent.
They're very similar towns in many ways (history, major ports, etc.).
In road terms, they're also both served by US 17 and bypassed by I-95.  And US 17 crosses the river shipping channels of each town on a high bridge.
Anyway....back to the topic.  I'll keep looking....

[tcorlandoinsavannah]

Until I-22 is complete, Birmingham and Louisville are fairly similar:

I-65:I-65
I-64:I-20/59 & I-20
I-71:I-59
I-265:I-459

The only difference is that Louisville has an extra bypass route in I-264

That looks pretty close to me.  Let's see how Duke87 calls it.

[vdeane]

Rochester and Albany, surprisingly enough, given that they have completely different geography otherwise.

I-87 <> I-/NY 390
I-787 <> I-/NY 590
I-90 <> I-490

NY 787 is even a divided highway with five at-grades and stop lights... just like NY 590 was from Titus to Culver before it was truncated.  Spooky.

[tcorlandoinsavannah]

Rochester and Albany, surprisingly enough, given that they have completely different geography otherwise.

I-87 <> I-/NY 390
I-787 <> I-/NY 590
I-90 <> I-490

NY 787 is even a divided highway with five at-grades and stop lights... just like NY 590 was from Titus to Culver before it was truncated.  Spooky.

I concur.  Well done.

[DandyDan]

If rotation were allowed, Fort Wayne, IN and Augusta, GA would be alike.

[vtk]

If rotation were allowed, Fort Wayne, IN and Augusta, GA would be alike.

Also Wheeling WV.

[Revive 755]

Until I-22 is complete, Birmingham and Louisville are fairly similar:

I-65:I-65
I-64:I-20/59 & I-20
I-71:I-59
I-265:I-459

The only difference is that Louisville has an extra bypass route in I-264

And the section of I-265 in Indiana between I-65 and I-64., which would require a connector between I-65 and I-20/I-59 in Alabama.

[tcorlandoinsavannah]

If rotation were allowed, Fort Wayne, IN and Augusta, GA would be alike.

Also Wheeling WV.

I'll agree with both of these.
The odd thing about Augusta, as far as I've been able to determine (Since I-520 doesn't appear in the 1955 Yellow Book), is that I-520 was not originally intended to link back to I-20 in SC (Otherwise, it should have been named I-220, since Augusta was the second capital of Georgia).  Anyway, I think that I-520's original purpose was to provide a direct link from Fort Gordon to the mainline interstate, then it eventually morphed into a loop around the metro area.  Most Augustans refer to it as the "Bobby Jones" anyway; they're not real good with numbers    .