[OSM-talk] Obvious turn restrictions
osm at inbox.org
Fri Jul 8 22:24:23 BST 2011
On Fri, Jul 8, 2011 at 1:04 PM, Ed Avis <eda at waniasset.com> wrote:
> Nathan Edgars II <neroute2 <at> gmail.com> writes:
>>North Elk Vale has been split into three ways with four relations on
>>each side of the overpass. And for what? To prevent a router from
>>telling you to turn right in the wrong part of the intersection?
> I think the essential problem is that you need to split a way into several bits
> to add these restrictions. It would be better if the schema for restrictions
> didn't require you to break ways in two. For example it might take a 'from' and
> 'to' way, an intersection node and an optional direction such as 'northbound'
> to disambiguate. That is slightly unclean in a strict geodata sense but
> perhaps better than the death by a thousand cuts we currently suffer when
> modelling complex junctions with the need to split a way at each point there is
> a junction node with some kind of restriction.
> That's just one idea. Another would be a 'lightweight' turn restriction schema,
> supplementing but not replacing the existing one, where properties can be tagged
> on the node itself ('no_turn', 'no_right_turn_northbound') avoiding the need
> for relations at all.
> Or perhaps editors just need better support for editing ways as a group to cope
> with the reality that things tend to get chopped into smaller and smaller bits
> as the map improves.
I think the latter is probably the most likely solution. Something
like that using relations wouldn't be too hard to do.
Also it's a solution which solves a lot of other problems, as there
are *lots* of reasons ways already get split (e.g. bridges), and lots
more to come as more information is added to the db (speed limits,
number of lanes, etc.).
More information about the talk