Re: dirt roads (Nathan Van Der Meulen)

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Re: dirt roads (Nathan Van Der Meulen)

Nathan Van Der Meulen
Ah dirt roads how difficult you are!  Firstly, just because a road is dirt (unsealed/unpaved) doesn't make it any less important than many others.  David, while the Plenty Hwy may be considered a 'track' by some (I have travelled the whole length of it quite recently and we passed a few Falcons and Commodores), it is in fact a NT state highway, as is the Sandover Hwy and Tanami Rd (Routes 12, 14 and 5 respectively) and should therefore, going by wiki guidelines, be classified as highway=primary.  Likewise the Birdsville, Strzelecki and Oodnadatta Tracks are all SA D roads and should all be highway=tertiary (Birdsville used to have a national classification).  These just need to have their additional tags like surface=unpaved, 4wd_only=yes (or recommended) etc.

I'm currently involved in a project using OSM data for map rendering and we're currently going over the issue of how to render dirt roads/tracks, what should classify as a dirt road or track and how to populate the outback with a few roads.  Currently we see highway=track as 4wd only tracks that don't serve a true connection purpose - these would be the real backwater tracks in the outback, or the majority of 4wd tracks on the east coast.  highway=unclassified are any sealed or unsealed roads that can't be classified as residential - such as 2wd forest drives (if you know the area, the Watagan Forest Drive is an example).  From there up it follows the wiki - and it doesn't matter if the road is 1 land or 8, 2wd or 4wd etc.  A 4wd track on the east coast can be a highway in the centre.  For our render, we use a different colour (brown) for all roads tagged unpaved, and are trying to get a dashed line for all roads tagged 4wd_only

Cheers
Nathan


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Today's Topics:

  1. dirt roads ([hidden email])
  2. Re: dirt roads (Matt White)
  3. Re: dirt roads (John Henderson)


----------------------------------------------------------------------

Message: 1
Date: Sun, 21 Oct 2012 11:33:21 +1030
From: [hidden email]
To: [hidden email]
Subject: [talk-au] dirt roads
Message-ID:
    <[hidden email]>
Content-Type: text/plain; charset="utf-8"


Hi Folks, recent I have been going over parts of OSM mapped some time
ago, following up on the infamous redaction. One thing that jumps out
at me is the inconsistent tagging of dirt roads. Even, I must say,
ones I have done myself but over a several year time span.

So I started to write some notes for myself and thought that maybe I
should add them to
http://wiki.openstreetmap.org/wiki/Australian_Roads_Tagging? I don't
think this is inconsistent with whats there now, just more detailed.
However, I do suggest that we need consider what the rendering engines
do with our data and I know that is a bit naughty. But, in this case,
I'd suggest to do otherwise is negligent as it can have quite serious
safety issues.

So, would people like to comment on what I say here ? If we can reach
consensus, I'll graft some of it onto the OSM wiki.

Unmade roads

These are typically forestry and remote tracks, while they may have
been cut initially by a bulldozer they are not regularly maintained
and, importantly, are not domed and don't have good run off gutters on
the side. Such roads might or might not be single lane, 4x4 only,
might be dry weather etc. Be careful about deciding on such
restrictions, some people are often surprised at how well a carefully
driven conventional vehicle can use these tracks. Highway=track will
typically render to a dashed line.
highway=track
surface=unpaved
lanes=[1; 2]
4x4_only=[recommended; yes]
source=survey

Made but unsealed roads.

Many rural roads fit here. There is no asphalt but the roads are
'made' and regularly maintained by, eg, the local council. These roads
often have a gravel base, always have dome shape, the middle is
somewhat higher than the sides and there is some sort of gutter at the
edge. The gutter will usually have "run offs" to drain water away from
the road. Such roads are almost never 4x4_only nor dry weather only.
highway=[unclassified; tertiary, secondary]
surface=unpaved
lanes=[1; 2]
source=survey

Use of the highway tag on dirt roads.

While the selection of tags should not be defined by how current
rendering engines display, we cannot ignore the final outcome. In
Australia, a lot of dirt roads are quite important and sometimes its
necessary to compromise a little to achieve a useful result. So the
correct highway tag may be determined by a combination of the purpose
of the road and its condition. Tracks are often rendered as dashed
lines and most people would understand that means some care may well
be needed. Unclassified would indicate a purely local function and is
typically rendered as two thin black lines with white between.
Tertiary? roads usually are rendered with two black lines and a
coloured fill and many people (incorrectly) interpret that as meaning
a sealed road, so maybe mappers should ensure they apply that tag only
to dirt roads that are reasonably well maintained. Secondary roads are
shown as wider and a different colour than tertiary and are definitely
presented as viable routes for people passing through the area. Some
care needs be exercised if a dirt road is to be classified as
'secondary'.

Discussion

Sometimes its hard to balance the description of a road against its
purpose. A good example might be the Plenty Highway. This road is
probably a track from a road condition perspective, rarely maintained,
sections of sand, corrugations and ruts. However, its pretty long and
a major link between some (admittedly small) communities. As a 'track'
it would not show up on a map until you zoom in way past where you can
get any idea of where it starts and ends. At time of writing, its
highway=primary (and, I might note, incomplete), that's possibly
dangerously misleading. Conventional vehicles routinely use it but I'd
probably give it a 4x4_only=recommended tag. However, none of the
mainstream rendering engines observe that tag, it is no real
protection for a visiting tourist.

Similarly, even on the east coast, its not unusual to see dirt roads
defined as 'tertiary' or even 'secondary'. Thats probably quite
correct from a purpose view but a lot of (especially city based)
drivers get quite nervous when they find themselves on a dirt road. If
they have got there by following a OSM map showing a road with
coloured fill, maybe they have a case ? Most printed maps here in
Australia show unsealed roads without a coloured fill.?

And this does, of course, highlight the need to survey roads.

David

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Message: 2
Date: Sun, 21 Oct 2012 12:33:24 +1100
From: Matt White <[hidden email]>
To: [hidden email]
Subject: Re: [talk-au] dirt roads
Message-ID: <[hidden email]>
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"

A couple of quick comments:

There is a 4wd tag already in use -  4wd_only:yes|recommended (with no
being a pointless value)
http://wiki.openstreetmap.org/wiki/Tag:4wd_only%3Dyes There's about 1000
instances of this tag in use in Australia.

There was a proposal kicking around ages ago that was trying to define
some improved classification for unpaved roads (as unpaved roads come in
all sorts of varieties). I think the discussion got pretty acrimonious
and petty, but the thought was there. There are roads I've been on where
the surface would be OK for a normal car, but the road is a series of
sharp humps that would easily ground a standard clearance vehicle.

Seasonal closure is another area where I don't think the tagging is
complete/useful. The current tag is dry_weather_only=yes or
access=dry_weather_only, which is valid for any road that is impassable
in the wet due to surface condition or creek/river crossings, but there
are also tracks with explicit closures (usually mid may to the first
weekend in September or October) - generally marked as 'SSC' in the
VicMap series of maps. Don't have a solution, but it something that
might need working on as there are a lot of SSC roads in Victoria and NSW

Anyway, I'm all for improved tagging of dirt roads - it's my favourite
kind of mapping (usually cos it turns out to involve a couple of days of
camping and getting out into the bush

Matt

On 21/10/2012 12:03 PM, [hidden email] wrote:

>
> Hi Folks, recent I have been going over parts of OSM mapped some time
> ago, following up on the infamous redaction. One thing that jumps out
> at me is the inconsistent tagging of dirt roads. Even, I must say,
> ones I have done myself but over a several year time span.
>
> So I started to write some notes for myself and thought that maybe I
> should add them to
> http://wiki.openstreetmap.org/wiki/Australian_Roads_Tagging  I don't
> think this is inconsistent with whats there now, just more detailed.
> However, I do suggest that we need consider what the rendering engines
> do with our data and I know that is a bit naughty. But, in this case,
> I'd suggest to do otherwise is negligent as it can have quite serious
> safety issues.
>
> So, would people like to comment on what I say here ? If we can reach
> consensus, I'll graft some of it onto the OSM wiki.
>
> Unmade roads
>
> These are typically forestry and remote tracks, while they may have
> been cut initially by a bulldozer they are not regularly maintained
> and, importantly, are not domed and don't have good run off gutters on
> the side. Such roads might or might not be single lane, 4x4 only,
> might be dry weather etc. Be careful about deciding on such
> restrictions, some people are often surprised at how well a carefully
> driven conventional vehicle can use these tracks. Highway=track will
> typically render to a dashed line.
> highway=track
> surface=unpaved
> lanes=[1; 2]
> 4x4_only=[recommended; yes]
> source=survey
>
> Made but unsealed roads.
>
> Many rural roads fit here. There is no asphalt but the roads are
> 'made' and regularly maintained by, eg, the local council. These roads
> often have a gravel base, always have dome shape, the middle is
> somewhat higher than the sides and there is some sort of gutter at the
> edge. The gutter will usually have "run offs" to drain water away from
> the road. Such roads are almost never 4x4_only nor dry weather only.
> highway=[unclassified; tertiary, secondary]
> surface=unpaved
> lanes=[1; 2]
> source=survey
>
> Use of the highway tag on dirt roads.
>
> While the selection of tags should not be defined by how current
> rendering engines display, we cannot ignore the final outcome. In
> Australia, a lot of dirt roads are quite important and sometimes its
> necessary to compromise a little to achieve a useful result. So the
> correct highway tag may be determined by a combination of the purpose
> of the road and its condition. Tracks are often rendered as dashed
> lines and most people would understand that means some care may well
> be needed. Unclassified would indicate a purely local function and is
> typically rendered as two thin black lines with white between
> Tertiary  roads usually are rendered with two black lines and a
> coloured fill and many people (incorrectly) interpret that as meaning
> a sealed road, so maybe mappers should ensure they apply that tag only
> to dirt roads that are reasonably well maintained. Secondary roads are
> shown as wider and a different colour than tertiary and are definitely
> presented as viable routes for people passing through the area. Some
> care needs be exercised if a dirt road is to be classified as 'secondary'.
>
>
> Discussion
>
> Sometimes its hard to balance the description of a road against its
> purpose. A good example might be the Plenty Highway. This road is
> probably a track from a road condition perspective, rarely maintained,
> sections of sand, corrugations and ruts. However, its pretty long and
> a major link between some (admittedly small) communities. As a 'track'
> it would not show up on a map until you zoom in way past where you can
> get any idea of where it starts and ends. At time of writing, its
> highway=primary (and, I might note, incomplete), that's possibly
> dangerously misleading. Conventional vehicles routinely use it but I'd
> probably give it a 4x4_only=recommended tag. However, none of the
> mainstream rendering engines observe that tag, it is no real
> protection for a visiting tourist.
>
> Similarly, even on the east coast, its not unusual to see dirt roads
> defined as 'tertiary' or even 'secondary'. Thats probably quite
> correct from a purpose view but a lot of (especially city based)
> drivers get quite nervous when they find themselves on a dirt road. If
> they have got there by following a OSM map showing a road with
> coloured fill, maybe they have a case ? Most printed maps here in
> Australia show unsealed roads without a coloured fill.
>
> And this does, of course, highlight the need to survey roads.
>
> David
>
>
> _______________________________________________
> Talk-au mailing list
> [hidden email]
> http://lists.openstreetmap.org/listinfo/talk-au

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Message: 3
Date: Sun, 21 Oct 2012 13:11:07 +1100
From: John Henderson <[hidden email]>
To: [hidden email]
Subject: Re: [talk-au] dirt roads
Message-ID: <[hidden email]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

On 21/10/12 12:03, [hidden email] wrote:

> lanes=[1; 2]

I thing the "lanes" tag is best not used, unless there's more than two
marked lanes on a two-way road, or more than one lane on a one-way road.

This is the recommendation in the Australian tagging guidelines:
http://wiki.openstreetmap.org/wiki/Australian_Roads_Tagging#Number_of_lanes

I have two reasons for arguing this.

Firstly, it's something else that would need checking when doing OSM
maintenance (and quite unnecessarily).  And it's something else to get
wrong if it's used routinely.  It's easier for everybody if its used is
reserved for the special cases.

Secondly, as an active mapper, I often download the whole of Australia
every week for use as route-proving on my Garmin GPSs.  If every road in
Australia had a lanes tag, that'd be a lot more data to download.

> Similarly, even on the east coast, its not unusual to see dirt roads
> defined as 'tertiary' or even 'secondary'.

I think a lot of roads get "pumped up" to be more important than they
are.  The great majority of country roads should be "unclassified".
It's hard to make a judgement as to when a different tag should apply.
Is it a main connecting road between towns with a Post Office?  How many
cars per hour travel it?

Another example is the tagging of the Hume Highway as a motorway.  Most
of it isn't.  The Hume Freeway in Victoria is, but most of the NSW
section has normal side-road junctions, and is certainly not a motorway.
By tagging it as a motorway, we've destroyed this useful distinction.

John




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Re: dirt roads (Nathan Van Der Meulen)

David Bannon-2
 

Hi Nathan, rather than difficult, I'm surprised how in agreement every one is ! Thanks folks !  If it goes on like this, I'll post a summary in a few days.

> From:
"Nathan Van Der Meulen" <[hidden email]>


> Firstly, just because a road is dirt (unsealed/unpaved) doesn't make it any less important than many others.

Far from it, I live on a dirt road !

>  David, while the Plenty Hwy may be considered a 'track' by some ...pass a few Falcons and Commodores),
Yeah, when I was there a few years ago, we passed a commodore, he had a broken rear axle.

> it is in fact a NT state highway ....
Yep, you have it in one. Thats the problem of trying to define both the purpose and condition of the road using just one tag.

> ....These just need to have their additional tags like surface=unpaved, 4wd_only=yes (or recommended) etc.
Exactly! But we need to see those tags used.

> I'm currently involved in a project using OSM data for map rendering
Cool, is the outcome for public consumption ?

> highway=track as 4wd only tracks that don't serve a true connection purpose
Hmm, I don't see it that way. Be happy to if thats agreed widely but its not how I have been mapping. The wiki includes forest drives and file trails under 'track', most of which are not exclusively 4x4.

> For our render, we use a different colour (brown) for all roads tagged unpaved, and are trying to get a dashed line for all roads tagged 4wd_only
Great, really great. But will the standards you use there be of any interest to the people making the main stream render engines ? Thats the problem IMHO, we put in these cool tags, 4x4_only= and surface= but it does not show up on the maps most people see.
Do you plan to differentiate between 4x4_only=yes and 4x4_only=recommended ?

Thanks (everyone) for the constructive input.

David




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