Interstate Interchange Puzzle

[CtrlAltDel]

A while ago, I was looking at the interchanges between (what I consider to be) the major interstates, and I made the following chart.



The problem is that I have forgotten what this is a chart of. Poking around, I see that a gray square indicates that there is no interchange between the routes in question. I also have surmised that C, P, and M, stand for complete, partial, and multiplex, and these letters most likely represents the type of interchange at the junctions in question.

I still, though, have no idea what Y and N stand for. I do know that it’s something I, as a road geek, cared enough about to make a chart, but past that, I got nothing. And so, I ask for your expertise to help figure it out. Any ideas you might have that are consistent with the Y’s and N’s as presented would be helpful.

[hotdogPi]

Y and N are almost certainly Yes and No.

Does "Y" correspond to where you have been (considering that the document is years old)?

[NE2]

65/90 isn't partial...

[inkyatari]

Adding Y and N equals 44.

Adding C, P and M also equal 44


Therefore I'd go with 1's answer of the Y and N meaning interchanges you've been to.

[sparker]

A while ago, I was looking at the interchanges between (what I consider to be) the major interstates, and I made the following chart.



The problem is that I have forgotten what this is a chart of. Poking around, I see that a gray square indicates that there is no interchange between the routes in question. I also have surmised that C, P, and M, stand for complete, partial, and multiplex, and these letters most likely represents the type of interchange at the junctions in question.

I still, though, have no idea what Y and N stand for. I do know that it's something I, as a road geek, cared enough about to make a chart, but past that, I got nothing. And so, I ask for your expertise to help figure it out. Any ideas you might have that are consistent with the Y's and N's as presented would be helpful.

Adding Y and N equals 44.

Adding C, P and M also equal 44


Therefore I'd go with 1's answer of the Y and N meaning interchanges you've been to.

Decent start -- now you can concentrate on classifying the interchanges by type (beyond simply complete or partial); here's something to get you going: S=stack (I-10/15)  C=simple cloverleaf (I-25/80)  T=trumpet (I-15/90 west)  D=direct otherwise (I-10/25) P= turnpike interchange involving toll barriers (I-80/90 Indiana).  You'll probably think of others as you look at them on maps or GE/GSV.  Have fun! 

[Pink Jazz]

I don't see why you don't consider I-85 major.  It isn't one of the longest Interstates, but is functionally important since it links many major cities in the Southeast.  I would consider it more important than I-25 since it is much more urban along its length and serves more major cities.  I-25 is not a route that most people would drive from end to end; I-85 on the other hand is the backbone of the Southeast.

[CtrlAltDel]

Y and N do indeed stand for the interchanges that I have traveled through (even if I didn’t use one of the ramps). Thank you everyone for that suggestion.

65/90 isn't partial...

You are correct. I will change my chart.

Decent start -- now you can concentrate on classifying the interchanges by type (beyond simply complete or partial); here's something to get you going: S=stack (I-10/15)  C=simple cloverleaf (I-25/80)  T=trumpet (I-15/90 west)  D=direct otherwise (I-10/25) P= turnpike interchange involving toll barriers (I-80/90 Indiana).  You'll probably think of others as you look at them on maps or GE/GSV.  Have fun! 

That does sound like fun. Perhaps I’ll post that chart later.

I don't see why you don't consider I-85 major.  It isn't one of the longest Interstates, but is functionally important since it links many major cities in the Southeast.  I would consider it more important than I-25 since it is much more urban along its length and serves more major cities.  I-25 is not a route that most people would drive from end to end; I-85 on the other hand is the backbone of the Southeast.

My criterion is indeed length. To count, in my reckoning, a north-south route has to be at least 800 miles long. It’s an arbitrary cut-off, I admit, but that’s about the length of the longer nonmajor north-south routes.

[hotdogPi]

My criterion is indeed length. To count, in my reckoning, a north-south route has to be at least 800 miles long. It's an arbitrary cut-off, I admit, but that's about the length of the longer nonmajor north-south routes.

I-81 is more than 800 miles long.

[OracleUsr]

95 to 40 isn't a full cloverleaf.

[US 89]

And 15 to 70 is a trumpet.

[CtrlAltDel]

My criterion is indeed length. To count, in my reckoning, a north-south route has to be at least 800 miles long. It’s an arbitrary cut-off, I admit, but that’s about the length of the longer nonmajor north-south routes.

I-81 is more than 800 miles long.

True, but it doesn't end in 5 (or 0). Just to clarify things, here are my official criteria:

To be considered a major interstate:
1. A route traveling north-south must
     A. Have a designation ending in 5 and
     B. Be at least 800 miles in length.
2. A route traveling east-west must
     A. Have a designation ending in 0
     B. Be at least 1500 miles in length.

There are a number of "good" routes that don't fit these criteria. I-94 and I-81 in particular would be major routes if I got rid of the 5/0 requirement. I-29 would also work, except for the 5/0 bit, if I lowered the length criteria to 750, that is, half the east-west length.

I want to insist that my way is not the only way to do these things. Here, I'm just explaining myself.

. . .

95 to 40 isn't a full cloverleaf.

And 15 to 70 is a trumpet.

In case there's any confusion, the C in my chart means "complete," not cloverleaf.