[Talk-us] Complex intersection mapping

Sat Nov 9 16:31:55 UTC 2013

James,

Thanks for the feedback. This is of course not good. I will make sure
we will be more careful with both the lane counts and the relations
not getting broken! I apologize. Did you fix the relations? If not I
will.

The case you highlighted - I agree this one would be just fine as a
single node. The guidance I have been giving, based on previous
discussion in this thread, was to only 'dualize' the intersection when
the dual carriageway clearly continues past the intersection. Does
that make sense? I will make sure we adhere to that guideline and not
overcomplexify situations that don't require it from a ground trouth
perspective.

Martijn

On Fri, Nov 8, 2013 at 9:47 PM, James Mast <rickmastfan67 at hotmail.com> wrote:
> Martijn (and other telenav workers),
>
> I just happened to see some intersections in my area tweaked today.  If
> you're going to be changing the intersections, can you at least please
> update the lane count on said ways if it's already been added at the same
> time?  I mean, if a way is on one side 4 lanes, and you split it into two
> separate ways, odds are both of them are 2 lanes each.  Yet, the lane count
> on them is still "4", which can also play screwy with the routing engines.
>
> Also, can you please update any relations that are attached to the highways?
> I'm going to bring up Changeset 18789658 as an example, which is the
> intersection of US-22 Business, PA-48, & the Orange Belt in Monroeville, PA.
> The two numbered routes were "broken" today (amazingly the Orange Belt
> wasn't) with the change from a 1-point intersection to a 4-point
> intersection.  I personally think that a 1-point intersection was completely
> justified for this intersection because of only two directions being divided
> when exiting it.  Anyways, US-22 Business now has a gap because of the "new"
> ways for it, and PA-48 now doesn't end @ the intersection anymore because of
> the divided highway from the North being extended outside the main
> intersection.  And, to be honest, I'm also toying with the idea of reverting
> said changeset to repair the relations and make it a 1-point intersection
> again, but wanted to bring it up here on the list first before doing that to
> prevent an edit war.
>
> So, if you keep doing it that way, can you please keep the collateral damage
> to a minimum when it comes to lane counts and highway relations?  I would
> really appreciate it when stuff like that was already tagged correctly
> doesn't need to be fixed again. :)
>
>
> -James (rickmastfan67)
>
>
>> From: martijnv at telenav.com
>> Date: Mon, 14 Oct 2013 11:42:53 -0600
>> To: talk-us at openstreetmap.org
>> CC: stevec at telenav.com; kristenk at telenav.com; roberts at telenav.com;
>> chrisz at telenav.com
>> Subject: [Talk-us] Complex intersection mapping
>
>>
>> Hi all,
>>
>> Here at Telenav we have been looking at complex intersections and we
>> have set about editing some of these intersections in a way we feel
>> represents the situation on the ground better than their original
>> state, and because of that, works better for us. We have received some
>> feedback on our edits so we wanted to take a step back and see what we
>> (as the OSM community) think is the preferred way to map these
>> intersections.
>>
>> So what are we talking about? Intersections like this one, where one
>> or more dual carriageways come together at an at-grade intersection:
>>
>>
>> https://www.evernote.com/shard/s9/sh/6438c196-bb92-4f66-81dc-9b75186286ba/0e8f07ff527c6a85c0dec426b9b79f1e
>>
>> One of my colleagues at Telenav has remapped this intersection as follows:
>>
>>
>> https://www.evernote.com/shard/s9/sh/3491f1fe-6afa-4571-bc43-7cb31c9c2625/9dd47d1445fdcf03d3f0bbd93b8e0f92
>>
>> The main difference, and the source of some feedback we have received
>> over the past few days, is that the dual carriageway roads are
>> straightened out, creating multiple intersection nodes (4 in this
>> case) instead of the original single intersection node that connects
>> all the incoming and outgoing ways. That technique turns out to yield
>> more reliable and correct routing and guidance ('keep left, turn
>> right') through these intersections in our testing. But of course,
>> that cannot dictate how we map as a community, so let's discuss.
>>
>> Some of the feedback we have received about these edits points to a
>> statement on this wiki page:
>> https://wiki.openstreetmap.org/wiki/TIGER_fixup#Braided_streets: 'It
>> is a reasonable and well-used technique to bring the ways of dual
>> carriageways back to a single point at intersections to facilitate and
>> simplify the mapping of control devices and turn restrictions.' In my
>> mapping across the US, my personal experience has been that this
>> technique is in fact used, but the 'after' technique with straightened
>> out ways is actually much more common. I personally prefer that
>> technique as well - I think it is more pleasing to the eye, represents
>> what is on the ground better, and is and easier to read. So my feeling
>> was that this mapping practice would not be disputed. It turns out I
>> was wrong, so I want to see what the consensus is on mapping
>> intersections of this type - or perhaps there is none and we can work
>> together to get there?
>>
>> Thanks,
>> Martijn
>> --
>> Martijn van Exel
>> OSM data specialist
>> Telenav
>> http://www.osm.org/user/mvexel
>> http://wiki.openstreetmap.org/wiki/User:Mvexel
>> http://hdyc.neis-one.org/?mvexel
>>
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-- 
--
Martijn van Exel
OSM data specialist
Telenav
http://www.osm.org/user/mvexel
http://wiki.openstreetmap.org/wiki/User:Mvexel
http://hdyc.neis-one.org/?mvexel