Changeset: 51597115
complex stop in one direction solved
Closed by Verdy_p
Tags
changesets_count | 6459 |
---|---|
created_by | iD 2.4.1 |
host | http://www.openstreetmap.org/edit |
imagery_used | LPI NSW Imagery |
locale | fr |
Discussion
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Comment from aharvey
I wouldn't exactly call it solved, as turning a road which has no physical separation between the directions into a dual way road creates issues which weren't there when mapped with a single way. But I guess now we have the stop mapped. +1
In OSM we almost need a way on the road centre line representing the physical road which is tagged as a painted solid line, painted dotted line, raised barrier (which can be driven over in an emergency), plastic poles or fence, along with other details about the road line name, classification.
And then separate set of ways representing the road network for routing with ways for different directions and lanes like it's been mapped in this changeset.
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Comment from aharvey
PS. I fixed up some of the turn:lane tags in https://www.openstreetmap.org/changeset/51802074
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Comment from Verdy_p
I'd like to know what are the "issues created" that this does not solve, given that there is effectively a separation (and separators are themselves mapped, notably the traffic islands).
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Comment from Verdy_p
Emergency situations may as well take any ways in forbidden directions, could use footways, enter private areas and even pass through unpaved areas (gardens...)
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Comment from aharvey
Sorry if I sounded negative, I really do appreciate you taking the time to work through this.
Two issues are:
1. You can turn across a solid white line (which is what's separating these two lanes to the south west of the intersection) to enter or leave a property. Mapped as a single way a router can direct you to a destination on either side of the street via either direction of travel on the road. Mapped out as dual way the router must direct you to your destination via only one of those ways (since normally dual carriage ways mean there is a physical separation which you can't cross).
I guess if physical separators (barrier=fence, traffic_island, raised curb, etc) are mapped out in theory routers could try to use that to distinguish dual ways with a physical separation and those with none, but I can see that getting quite messy and to get right.
2. It makes it much harder if not impossible to measure total road length from the OSM database as this single road is no longer the road center-line but instead the center-lane-line. This is less of a concern as it's a problem with the accepted way to map physically separate ways as dual ways, so not really specific to this case. -
Comment from Verdy_p
Point 1 is false. You can't cross the solid line evenwhen exiting a private property. The one way must still be respected and you'll have to go to the next crossing where this will be possible.
Point 2 is not relevant at all. The center line is not better than measuring on the center of any lane, and the effect disappears rapidly with the various curves to the left or right. The variation is also affected by the precision of polygonal lines used to approximate the real curves. Any total length distance will not be measured to the centimetric precision where this has a significant effect only on short distances, but where the center line is not relevant at all and the actual lane will be much more precise ! You can have better precision just by adjusting the polygonal lines to better appromixate the curves, but most ways still have too sharp segments zigzagging between the leftside and right side of the roads, including over sidewalk and their exact length is not represented.
Here you'll note that I took the time to imporve the curves to reduce this effect and this cannot be worse than the previous approximation of the "centerline"But the presence of trafic islands and other separators cannot be ignored: it even helps drivers to be notified earlier of when to take the correct lane: they'll be notified sooner if they know that lanes are separated long before the actual crossing and this is expected. So I don't see the point of where this could really cause any problem to separate these lanes early where they are effectively marked or barred.
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Comment from aharvey
1. Not in this jurisdiction. http://www.rms.nsw.gov.au/roads/safety-rules/road-rules/road-markings.html "Drivers are permitted to cross a single dividing line enter or leave a road".
2. I'm not talking about measuring distance for a route, this is irrespective of navigation. It's purely the fact that we no longer have a centre line representation of this non-physically separated road. Which is a loss, but you're right that practically there is not much impact.
Ways (16)
- Mowbray Road (520146351), v1
- Mowbray Road (520146352), v1
- Mowbray Road (520146353), v1
- Mowbray Road (520146354), v1
- Mowbray Road (520146355), v1
- Mowbray Road (520146356), v1
- 520146357, v1
- Mowbray Road (520146358), v1
- Mowbray Road (181927328), v5
- Mowbray Road (181927327), v9
- 518743601, v2
- Hampden Road (173242380), v10
- Mowbray Road (181927329), v5
- Mowbray Road (181927326), v14
- Mowbray Road (181927325), v4
- Orchard Road (455812236), v2
Relations (3)
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