CA: Interstate "dangling ends"

[oscar]

Following on the earlier discussion of dangling ends in Arizona, and the current discussion of Idaho 41's south end, we have some similar issues with the east end of I-105 in the Los Angeles metro, and the west end of I-780 in the outer reaches of the San Francisco metro. We went no-build in Arizona, and think that's probably the right result here too.

California's Postmile Query Tool online mapping, and FHWA online mapping of Interstate routes, indicate that route 105 extends east of I-605 to end at Studebaker Road, and that route 780 extends west of I-80 to end at Lemon Street. However, when I was there last year, I saw no signage confirming those results, totally unclear whether the routes extend past the intersecting Interstates. Neither Lemon St. nor Studebaker Rd. is a TM-mapped route, so no need to create graph connections with those routes.

An extra complication with I-105 is that the freeway east of I-605 is 24/7 HOV-restricted, limited to buses and carpools (including to and from a light-rail/bus/park-and-ride transit station). I traveled it anyway. No harm, no foul, no cop or camera, no ticket.

Anyway, unless we're treating Interstate dangling ends differently from state route dangling ends, I think we don't need to do anything here.

[neroute2]

Neither I-105 entrance from Hoxie Avenue is marked as carpools/buses only, so it's legal to clinch by looping.

[Duke87]

One way or another some changes are necessary here since current implementation is inconsistent.

For example:
- I-605 is mapped going to Huntington Drive when it is not explicitly signed as extending north of I-210
- I-295 (NY) is mapped as going to NY 25 when it is not explicitly signed as extending south of the Grand Central Parkway

If we're not mapping unsigned dangling ends on the interstate system, these (and possibly others, I have not poked around comprehensively) need snipping.

That said, I don't necessarily favor this. For state routes, we long ago decided that what is or isn't signed overrules what exists on paper. But we map interstates even when they aren't signed and have done so since the beginning, so the rules for interstates already are different. I would, for interstate highways and for interstate highways only, lean towards using the official definition over the signs on account of this.

[vdeane]

- I-295 (NY) is mapped as going to NY 25 when it is not explicitly signed as extending south of the Grand Central Parkway

Sure, it's not perfect, but I'd consider stuff like this as fairly indicitive as I-295 going to NY 25, especially given NY's precedent for not signing such things.  Sure, it's not the smoking gun we might like, but not every jurisdiction is Ontario (note that the street view is from the era when ON 417 ended very soon after that interchange and there was a discussion regarding whether to break 1PPI to match the signage).  The I-490 example isn't even the last interchange.

[oscar]

For state routes, we long ago decided that what is or isn't signed overrules what exists on paper. But we map interstates even when they aren't signed and have done so since the beginning, so the rules for interstates already are different. I would, for interstate highways and for interstate highways only, lean towards using the official definition over the signs on account of this.

Good point. I'm now leaning to extending I-105 and I-780 as described above. But I'll hold off for now, to let others weigh in.

[cl94]

780 is an interesting case. Like the NY examples linked above, the ending is ambiguous on the surface aside from a blade, but everything points to it beginning at Lemon (most importantly the Caltrans logs). I support inclusion.

105 is fun because yes, it requires some unusual movements to legally drive it as a single-occupant vehicle. But both the postmile tool and postmiles on the surface have it ending at Studebaker. I support inclusion. Note that, even if it were illegal to drive as an SOV, I'd be for including it because there is precedent for including normally-undrivable routes that meet the other standards for inclusion. See NC 172, NJ 68, and M-185. But unlike two of those, it is legal for civilians to travel 105 in a single shot by having a passenger or riding a bus.

[oscar]

https://github.com/TravelMapping/HighwayData/pull/5731
https://github.com/TravelMapping/HighwayData/pull/5733