JPN: E58 main route

[yakra]

E58
a) The branch from exit 1-1 to exit 1 is the end section of the Okinawa Expwy.  Is it a branch or just a long exit? Exit 1 is at the end of it.  The Naha Airport Road was appended to E58 at junction 1-1 in 2000.  Exit 1 was probably the original southern end of E58.

Just going on the exit numbering here, maybe could the shorter leg be considered part of the mainline route, and the other one, despite being longer, could be considered a branch to go in a separate file?
What if anything does JPN's DOT-equivalent have to say on the topic?
Do they use some form of km-posting?

Should these exits be A1(N506) etc?
Or should N506 possibly reference E58?

[nezinscot]

KM posts are common on expressways.  I checked and KM 0 is at the point where Exit 1 meets P82.  The extension to the airport has a different numbering scheme - KM 0 is at the toll both where it joins the older E58 route.

I like your suggestion to make the shorter leg part of E58 and make the airport extension E58Something.   Should I make the change?  No user lists have references to E58.

[yakra]

Should I make the change?

For my part, I don't know enough about the ins & outs of Japan to know whether that's appropriate.

[michih]

KM posts are common on expressways.  I checked and KM 0 is at the point where Exit 1 meets P82.  The extension to the airport has a different numbering scheme - KM 0 is at the toll both where it joins the older E58 route.

I like your suggestion to make the shorter leg part of E58 and make the airport extension E58Something.   Should I make the change?  No user lists have references to E58.

Go for it if si404 - who drafted the system - is fine with it.

I think it is a rare case where an update entry is not required. Not because there is no traveler yet but because it is only a technically TM change which is not relevant for historic reason.

[si404]

Just going on the exit numbering here, maybe could the shorter leg be considered part of the mainline route, and the other one, despite being longer, could be considered a branch to go in a separate file?

I had it the other way around because we're meant to go with the longer legs as part of the mainline.

Though I can't seem to find that in the manual - was that a Tim rule that I've just assumed is something more formal?

Go for it if si404 - who drafted the system - is fine with it.

You don't need my permission (and, if anything, if you think I drafted the system wrong here, then my opinion isn't worth much). Though sure, it's nice to be asked and worth getting an explanation for why its like that to inform the decision.

I'm happy about the proposed change if there's a consensus. There's almost certainly others in Japan that could have similar treatment too.

[michih]

Go for it if si404 - who drafted the system - is fine with it.

You don't need my permission (and, if anything, if you think I drafted the system wrong here, then my opinion isn't worth much). Though sure, it's nice to be asked and worth getting an explanation for why its like that to inform the decision.

It was meant: Don't jump the gun but wait for a response from si404 who drafted the system and might have done it on purpose and might explain why. And might remember similar cases.

[yakra]

The only time I remember route length coming into play in CHM was, if there are 2+ separate pieces of a same-numbered (or named) route, then the longest one is the "main" piece, without an abbrev.
I don't believe the idea of 2 routes branching apart, with ambiguity over which branch would be part of the "main" piece, came into play; I don't think it had been conceived of back then.
I wanna say this is something that's still not explicitly addressed now -- and probably shouldn't be; most likely best handled on a case-by-case basis.

[michih]

Nothing was changed so far. Is there consensus to change it or do we want to keep it as-is and mark this topic solved?

I have no strong feeling on it but tend to keep it as-is.

@nezinscot @yakra et al

[nezinscot]

My preference would be to move the airport extension into E58Nah?? and have E58 extend along the current E58Shu.  The airport extension is N506, so making this change would make E58Nah and N506 fully concurrent.  But I'm also fine with leaving it like it is.

[neroute2]

Do km posts follow the E routes per se, or the named expressways that the E routes follow (often having multiples)? As a U.S. example, if the New Jersey Turnpike south of exit 6 were signed as part of an unbannered bypass of I-95, that wouldn't automatically make it main I-95, despite mileposts being continuous from Deepwater to Fort Lee.

[nezinscot]

The km posts are usually based on the individual highways , so any E road made from multiple existing expressways will have multiple km post sets, but only one set visible at a time.

E58Shu km 0 is at the Naha IC and the numbering ascends to the north end of E58 in Kyoda. 
The Airport Toll Road piece of E58 has km 0 at the Nishihara JCT when it meets E58Shu. Numbering ascends to the south.