[Talk-us] Complex intersection mapping

[Martin Koppenhoefer]

2013/10/15 Minh Nguyen <minh at nguyen.cincinnati.oh.us>

> ** Example A **
>
> Ryans Way and Sycamore Grove Ln. meet Fields Ertel Rd. at the same
> intersection. Fields Ertel is undivided. Ryans Way is briefly divided at
> the subdivision entrance, a very common configuration in newer
> subdivisions, but Sycamore Grove is not.
>
> I mapped the intersection as a single point:
>
> <http://nguyen.cincinnati.oh.**us/minh/osm/talk-us/braided_**
> intersections/ryans_before.png<http://nguyen.cincinnati.oh.us/minh/osm/talk-us/braided_intersections/ryans_before.png>
> **>
>
> Your colleague redrew it as a two-point intersection, dividing the very
> tip of Sycamore Grove (to the south):
>
> <http://nguyen.cincinnati.oh.**us/minh/osm/talk-us/braided_**
> intersections/ryans_after.png<http://nguyen.cincinnati.oh.us/minh/osm/talk-us/braided_intersections/ryans_after.png>
> >
>
> I prefer the former approach, because the latter shows a false traffic
> island on the south side of the intersection. Imagine a pedantic navigation
> tool that tells a driver coming from Sycamore Grove to "keep/bear right and
> immediately turn left".
>


+1, before is better, after is "false" according to current conventions.



>
> ** Example B **
>
> A divided Main St. intersects a divided Remick Blvd. Like everyone else
> here -- and unlike the "before" example Martijn provided -- I prefer a
> four-point intersection. But just to the east, Remick and a service road
> both become undivided at the same intersection. I mapped it as a single
> point:
>
> <http://nguyen.cincinnati.oh.**us/minh/osm/talk-us/braided_**
> intersections/remick_before.**png<http://nguyen.cincinnati.oh.us/minh/osm/talk-us/braided_intersections/remick_before.png>
> >
>
> Your colleague redrew it as a four-point intersection, this time with two
> triangles:
>
> <http://nguyen.cincinnati.oh.**us/minh/osm/talk-us/braided_**
> intersections/remick_after.png<http://nguyen.cincinnati.oh.us/minh/osm/talk-us/braided_intersections/remick_after.png>
> **>
>



again before is better and after is problematic for the reasons you
described. The problem introduced in the after versions  is btw. the same
problem also existent in the after picture that Martijn showed in his
initial post (a single carriageway discharging into a dual carriageway
should not become itself a dual carriageway, in the original posting this
was the way coming from the east/right).

cheers,
Martin
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