[Talk-us] Fwd: Separate relations for each direction of US & State highways.

Wed Nov 20 22:48:35 UTC 2013

Hi all,

Kristen meant to sent this to the list but her emails keep bouncing,
which seems to have something to do with our Telenav mail servers.
See below for her input on the directions topic, she did some
interesting research into how various routing engines and mappers have
dealt with this in the past.

Best
Martijn

---------- Forwarded message ----------
From: Kam, Kristen -(p) <kristenk at telenav.com>
Date: Wed, Nov 20, 2013 at 3:41 PM
Subject: RE: [Talk-us] Separate relations for each direction of US &
State highways.
To: "Van Exel, Martijn" <martijnv at telenav.com>, James Mast
<rickmastfan67 at hotmail.com>
Cc: talk-us <talk-us at openstreetmap.org>, "Zontine, Chris -(p)"
<chrisz at telenav.com>, "Lemberg, Vladimir" <vladimirl at telenav.com>,
"Yu, Haifeng (Chris)" <haifengy at telenav.com>, "Martijn van Exel
(m at rtijn.org)" <m at rtijn.org>

James+Community,

I am the editor you called out in your e-mail on Monday. This is my
response. Please note although I can receive messages posted on the
talk-us mailing list, I cannot post to this list at this time. I am
running into technical difficulties and I am working with Ian Dees to
resolve them. For now, Martijn will just forward this message to the
list.

A fellow Telenav OSM editor and I have been making edits as an effort
to solve the problem of the lack of cardinal direction information on
highway route relations within the United States. Our reasoning is
that the lack of cardinal directions for highway routes affects the
guidance/routing quality. As you mentioned in your November 17, 2013
message to the talk-us mailing list, you would like routers to
properly tell the direction of the highway folks would need to turn
onto. It can be safe to say that you and I agree that this is a
problem that would need to be solved.

We took a look at the attributes of the existing highway route
relations within the United States. We found that individuals employed
one of the two following methods in adding cardinal direction
information:

For route relations entirely comprised of ways representing one
direction of the highway route, the route relation had a direction=*
tag value of north/south/east/west.  The case of the values varied,
but individuals set cardinal direction values to the direction tag of
the relation.
For route relations that are comprised of ways representing both
directions of a highway (dual carriageway) or bi-directional road
segments, individual editors set the member role to a cardinal
direction the way represented. We reviewed the OSM wiki page
(http://wiki.openstreetmap.org/wiki/Relation:route) on route relations
and found these values were consistent with the cardinal direction
Member roles values listed on said wiki page.

When looking at the data in more detail, we found a preponderance of
relations that were edited to use the member role method cited above
more than the direction=* tag method.  Since both methods were
employed to handle the setting of cardinal direction information to
highway route relations, we decided to incorporate both methods in our
editing routine. Depending on the situation, of course. We considered
splitting existing to smaller relations based on their direction--as
discussed in the talk-us mailing list--but we adopted the member
role/direction=* tag method because it is less expensive (who wants to
create more relations?), less complicated, and consistent with the
existing editing practices we observed.

A handful of route relations not edited by us that are consistent with
our editing routine include:

http://www.openstreetmap.org/browse/relation/215687 (user StellanL)
http://www.openstreetmap.org/browse/relation/228529 (user ToeBee)
http://www.openstreetmap.org/browse/relation/156379 (user dchiles)
http://www.openstreetmap.org/browse/relation/155931 (user NE2)
http://www.openstreetmap.org/browse/relation/335542 (user NE2)

You have mentioned for the need to incorporate cardinal direction
information into existing routers. That got me thinking, “Are there
existing routing engines that use existing cardinal direction
information?”  I took a look at the OSRM and the Mapquest Open routing
engines. Both use OSM data as the base map and for routing/guidance.
The reason why I only tested both is due to the fact that I do not own
a smart phone (brick phone for the win!).  Please take a look at the
cases, which are listed in a word document that is attached to the
following Evernote:

https://www.evernote.com/shard/s366/sh/8bad0862-ace2-4085-bebd-2b9f986a915e/7ecb2153773925234db05370c5cb6ea8

To summarize my investigation: The OSRM routing engine does not
provide highway direction information into their guidance.  However,
the Mapquest Open routing engine appears to incorporate cardinal
direction member role values for interstate or state highways route
relations, that are ENTIRELY comprised of motorways, into their
routing/guidance.

In summary, the point I am trying to make is that we’re not
re-inventing the wheel in terms of relation tagging conventions or
setting member roles values of existing relations’ members.  Merely,
we are incorporating existing practices into our routine. The cases
cited in the Evernote demonstrates that other OSM data consumers’ are
making the mapping practice observations we have been making. And they
are incorporating this information into the construction of their
OSM-driven products.

That’s pretty much it. I look forward to your and other talk-us
subscribers’ response.

Best,

Kristen

---

OSM Profile → http://www.openstreetmap.org/user/KristenK

-----Original Message-----
From: mvexel at gmail.com [mailto:mvexel at gmail.com] On Behalf Of Martijn van Exel
Sent: Wednesday, November 20, 2013 11:32 AM
To: James Mast
Cc: talk-us; Kam, Kristen -(p); Zontine, Chris -(p); Lemberg,
Vladimir; Yu, Haifeng (Chris)
Subject: Re: [Talk-us] Separate relations for each direction of US &
State highways.

Hey all,

Reading through this I see that most are in favor of avoiding dividing
relations more than necessary: no separate relations for directions,
especially not if the geometry is the same for both.

That leaves the question of how to tag cardinal directions? As I said
before, I think the role tag is suitable for this. It's already used
pretty widely (with around 100k ways having a cardinal direction as
the role tag in a relation), documented
(https://wiki.openstreetmap.org/wiki/Route#Members) and it replaces
the forward / backward role values that are not particularly useful or
meaningful.
I created a stub of a wiki page that we could use to describe the
preferred tagging in more detail:
http://wiki.openstreetmap.org/wiki/Highway_Directions_In_The_United_States.
(The current content is geared towards using the member role tag, but
this can be changed depending on the outcome of this discussion.)

Here at Telenav we can commit to doing much of the work completing the
cardinal direction tagging, and we're eager to get started, but I do
want to ensure that we're following best practices.

On Tue, Nov 19, 2013 at 8:38 AM, Martijn van Exel <martijnv at telenav.com> wrote:
> James,
>
> This does warrant an explanation for sure. Kristen is one of my
> colleagues here at Telenav and we discussed best editing practices for
> cardinal direction information here internally. The plan was to take
> the discussion to this list before proceeding on any kind of scale. I
> managed this poorly and this did not happen yet. For this I apologize!
> I have made sure that we take a step back and have this discussion
> first before proceeding.
>
> Back to the topic at hand. We discussed options for adding cardinal
> direction information to route relations. We considered but dismissed
> splitting route relations at direction breaks and adding direction= to
> each relation - to my mind, this would make for a contrived relation
> hierarchy for a relatively simple information element. The remaining
> viable alternative to my mind is then to edit the role tag to reflect
> cardinal direction. This makes sense to me for a number of reasons:
> leveraging a tag that already exists and does not contain particularly
> useful / relevant values (forward / backward); the practice is already
> documented and pretty widely used, and lastly, it's transparent and
> explicit.
>
> More generally on relation maintenance, I think we may need some
> better tools to monitor / repair broken relations. I know there are a
> few tools out there (I link to some of them on the relation pages) but
> I am wondering if we would benefit from some kind of automated
> relation integrity checking? If so what would that ideally look like?
> If there's interest, will see what we could do here to build
> something.
>
> Looking forward to hearing your thoughts.
> Martijn
>
> On Mon, Nov 18, 2013 at 11:41 PM, James Mast <rickmastfan67 at hotmail.com> wrote:
>> Well, one of the main reasons I brought this up is because I've
>> noticed another user changing some relations from "forward/backward"
>> to "west/east"/"south/north" without discussing this here on talk-us.
>> That user would happen to be KristenK.  This user has been doing this
>> since the 11th at least all across the US.  Maybe a block is needed
>> so he can explain here on talk-us why he's doing all these mass
>> edits? (or was this a challenge on Battle Grid that I wasn't aware
>> of?)  Only reason I just noticed this was because a recent change of
>> his edits finally triggered in one of my RSS feed watch areas (US-30 WV relation).
>>
>> Another reason is for those rare US highways that change posted
>> cardinal directions within one state (US-98 is posted both
>> North/South and East/West in Florida), or change at state borders
>> (US-35 and US-52 do this several times).  We need to figure out a way
>> to account for this so that the routers give the person the correct
>> info.  As we do know, diagonal routes can be a major pain in this area.
>>
>> -James (rickmastfan67)
>>
>> _______________________________________________
>> Talk-us mailing list
>> Talk-us at openstreetmap.org
>> https://lists.openstreetmap.org/listinfo/talk-us
>>
>
>
>
> --
> --
> 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

--
--
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

-- 
--
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