Re: [talk-au] maxspeed - best practice?

[Ian Sergeant]

Ben Johnson  wrote:

> On the subject of tagging "site unseen"... you brought up a  perfectly
> legit point about routers and efforts made in the past to  assist routing
> engines. I'm just trying to get a sense where our  community stands in
> relation to maxspeed tagging "site unseen", for  residential streets, and
> how we identify such tagging.

Just to be clear, I'm totally against speed limit guessing based on
highway=* type.  (site unseen maxspeed tagging).

I understand the motivations: that you don't have to change the
router, that it encourages corrections and more maxspeed info to be
added.

It is just that adding potentially millions of default maxspeed tags
to residential streets, rather than adding one line of code to a
router or exporter seems totally skewed to me, especially when in most
case the routing applications will work just fine on residential
streets (mostly non-through ways, after all) without this information.
 Most routers aren't (and shouldn't be) directing people to use
residential streets as through routes.  Routers presuming a too low
speed for residentials (the speed in AU is relatively high) usually
yields a satisfactory outcome even when the residential roads don't
have a tagged maxspeed.

Well intentioned default speed tagging may in fact have the opposite
effect, for example in the OSRM default configuration it will cause
routing to use residential roads tagged with maxspeed=50, rather than
taking a tertiary road with a lower default maxspeed.

My only concession to routers, would be that if you maxspeed tag a
residential street you should try and also tag the connecting ones if
possible, so that routing anomalies don't happen due to speed
presumptions.

Ian.

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Re: [talk-au] maxspeed - best practice?

[Mark Pulley]

Quoting Ben Johnson :

On the subject of tagging "site unseen"... you brought up a   
perfectly legit point about routers and efforts made in the past to   
assist routing engines. I'm just trying to get a sense where our   
community stands in relation to maxspeed tagging "site unseen", for   
residential streets, and how we identify such tagging.


Im thinking one of these might serve that purpose...

source:maxspeed=default
source:maxspeed=unconfirmed
source:maxspeed=fixme
source:maxspeed=presumed


rather than using source:maxspeed=fixme I'd prefer fixme=check  
maxspeed - maybe in combination with source:maxspeed=default or  
something similar.


Mark P.



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Re: [talk-au] maxspeed - best practice?

[John Henderson]

On 15/08/12 06:49, Ben Johnson wrote:

It's part of a traffic zone proposal. It derives values based on the
 country and type of zone. It looks like it can be an effective way
to define an entire set of tags that should apply consistently
across a group of ways (eg a method for all ways in a defined
"built-up" area to share a common set of key/values including
maxspeed, and other rules).

http://wiki.openstreetmap.org/wiki/Proposed_features/trafficzone#Examples





and bottom of

http://wiki.openstreetmap.org/wiki/OSM_tags_for_routing/Maxspeed#Implicit_maxspeeds_set_by_.22trafficzone.22_and_.22highway.22





I guess the danger with this again is presumptions!!!

Interesting.  But it's only a proposal at this stage.  For the time
being, I'd argue for adherence for the existing maxspeed tag value types
at http://wiki.openstreetmap.org/wiki/Key:maxspeed

John

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Re: [talk-au] maxspeed - best practice?

[Ben Johnson]

It's part of a traffic zone proposal. It derives values based on the country 
and type of zone. It looks like it can be an effective way to define an entire 
set of tags that should apply consistently across a group of ways (eg a method 
for all ways in a defined "built-up" area to share a common set of key/values 
including maxspeed, and other rules).

http://wiki.openstreetmap.org/wiki/Proposed_features/trafficzone#Examples

and bottom of 
http://wiki.openstreetmap.org/wiki/OSM_tags_for_routing/Maxspeed#Implicit_maxspeeds_set_by_.22trafficzone.22_and_.22highway.22

I guess the danger with this again is presumptions!!!

This may not be the best solution, but it ties in with the whole definition of 
"built-up" areas and the laws that are associated with them... and seems to be 
an elegant way to tag an area consistently.

BJ


Sent from my iPad

On 15/08/2012, at 2:51, John Henderson  wrote:

> On 15/08/12 02:26, Ben Johnson wrote:
>> I really like this, but I think your "source:maxspeed=AU:urban" below
>> is a typo. It would be simply
>> 
>> maxspeed=AU:urban
> 
> The problem is that "AU:urban" isn't numeric.  It isn't a speed at all.
> 
> John
> 
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Re: [talk-au] maxspeed - best practice?

[John Henderson]

On 15/08/12 02:26, Ben Johnson wrote:

I really like this, but I think your "source:maxspeed=AU:urban" below
is a typo. It would be simply

maxspeed=AU:urban


The problem is that "AU:urban" isn't numeric.  It isn't a speed at all.

John

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Re: [talk-au] maxspeed - best practice?

[Ben Johnson]

Hi John,

I really like this, but I think your "source:maxspeed=AU:urban" below is a 
typo. It would be simply 

maxspeed=AU:urban

Does anyone else have thoughts on this? Could this be our default (site-unseen) 
for residential streets - or is this an across-the-board solution and we 
combine it with a source:maxspeed tag of some form to determine whether 
site-unseen or surveyed.

John - as for the Wiki, I agree with you, a lot of Aussie stuff needs to be in 
the Wiki, and following global standards if they exist. A lot of useful stuff 
gets discussed in here, but I believe the bulk of contributors do not subscribe 
to talk-au. They probably don't know or care about list. They use JOSM / 
Potlatch presets as an editing guide - failing that, they fall back on the Wiki 
and the Help Centre for clarification.

I see a useful role for talk-au to be a melting pot for ideas and local 
policies that should be disseminated via the Australian sections of the 
Wiki but, who has the time and motivation to take on this task is another 
matter!!!

BJ


Sent from my iPad

On 14/08/2012, at 16:52, John Berkers  wrote:

> I was looking into this some time ago as well.  The standard in other parts 
> of the world, according to the wiki, for default speed limits is to tag like:
> 
> source:maxspeed=AU:urban
> 
> If there is a sign designating the speed limit, the wiki indicates it should 
> always be tagged
> 
> source:maxspeed=sign
> 
> If there are markings on the road:
> 
> source:maxspeed=markings
> 
> I know that, in Victoria at least, all areas other than urban/residential are 
> either sign-posted or have road markings.
> 
> My view is that, where possible, we should use a similar standard to what is 
> use around the world for this.  I don't think it is particularly helpful to 
> use a long, descriptive string like "default residential speed limit in 
> Australia" since it is intended for use primarily by a routing application a 
> map renderer.
> 
> Perhaps it is time to add Australia to the list of countries on:
> 
> http://wiki.openstreetmap.org/wiki/OSM_tags_for_routing/Maxspeed
> 
> Does anyone else have a point of view on this with respect to Australia?
> 
> Regards,
> 
> John Berkers
> 
> On Tue, Aug 14, 2012 at 3:30 PM, Ben Johnson  wrote:
> In regards to residential areas - I remember last year there was some talk 
> about the bot that added "50" with the (incorrect) "maxspeed:source" key = 
> "default residential speed limit in Australia"  and I think there was 
> consensus in the local community that this was a mistake.
> 
> With remapping some of my local areas, I'm now curious what's best practice 
> in Australia is for tagging maxspeed on residential streets. Specifically...
> 
> a) is it even necessary or desirable to explicitly define maxspeed for every 
> residential way - or should we just presume any highway=residential is 
> maxspeed=50, unless otherwise stated?
> 
> b) if presumptions do exist, should 50 zones on tertiary and unclassified 
> ways be explictly tagged ?
> 
> c) if tagging maxspeed on every street, in respect to source... does a simple 
> source:maxspeed=sign suffice for the "general area" or only for the specific 
> way on which the sign is placed?  I notice these residential 50 speed signs 
> are often on tertiary streets, or gateway points into general residential 
> areas.  Side-streets obviously share the 50 limit, but are mostly not 
> signposted. Do we need a new standard source value like 
> source:maxspeed=implied for the side streets ?
> 
> Sorry if I'm re-covering old ground - I'm just not sure where it was left... 
> if anywhere!
> 
> Thanks in advance.. BJ
> 
> 
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Re: [talk-au] maxspeed - best practice?

[Ben Johnson]

On 14/08/2012, at 16:44, Ian Sergeant  wrote:

> Hi,
> a) The thing is, if you don't tag maxspeed=50, then how do tell a residential 
> road that is known to be maxspeed=50, against one that is just un-surveyed, 
> and might be maxspeed=30,40 or 60?

Yes... always the exceptions that create the mountain of work!


> c) source:maxspeed=sign is clearly correct if there is a sign. If you've 
> surveyed around an area, and there isn't a sign, personally I'd tag 
> source:maxspeed=survey.  The alternative here, would be 
> source:maxspeed=default or some such, but given our history of tagging "site 
> unseen".   It  I think this is best avoided. Same goes for source=implied for 
> the same reason.  If you've visited and determined the speed limit, it is a 
> survey.   maxspeed=local_knowledge if you drive around the residential 
> streets in your area all the time, and you just know they are all 50km/h.

That's a tidy differentiation between sign, survey and local_knowledge.  I've 
sometimes struggled with the differences. From now on I'll refer back to this!  
We need to get this onto the wiki.

On the subject of tagging "site unseen"... you brought up a perfectly legit 
point about routers and efforts made in the past to assist routing engines. I'm 
just trying to get a sense where our community stands in relation to maxspeed 
tagging "site unseen", for residential streets, and how we identify such 
tagging.

Im thinking one of these might serve that purpose...

source:maxspeed=default
source:maxspeed=unconfirmed
source:maxspeed=fixme
source:maxspeed=presumed

It would be a stop-gap measure to assist routing engines, and we can later use 
such tagging to flag areas needing proper survey. And then there's the aspect 
that once something is surveyed, it needs periodic review ... but that's a 
whole new consideration.


> Just an aside,  a simple case study in presumptions.  Probably the most 
> popular OSM open source router is OSRM.  The speedprofiles for that project 
> you can see here
> 
> https://github.com/DennisOSRM/Project-OSRM/blob/master/speedprofile.ini

Thanks. I knew this existed somewhere... but had no idea it was using 25! 
Clearly there's too many exceptions and unknowns - even if the profile was on a 
country-by-country basis, we have layers of government authorities wanting to 
set their own rules and it's forever changing.

BJ




> 
> I believe OSRM will use a maxspeed on a street if it finds one, so once you 
> start marking maxspeeds it makes sense to mark others around them, otherwise 
> a maxspeed=40 road will become a preferred road over other residentials and 
> secondaries.
> 
> I'm sure the motivation for tagging all residentials as maxspeed=50 was 
> partly an attempt to address this issue. 
> 
> Of course, there is a good argument for this being fixed in OSRM, or in 
> post-processing the AU data, etc.
> 
> Ian.
> 
> On 14 August 2012 15:30, Ben Johnson  wrote:
> In regards to residential areas - I remember last year there was some talk 
> about the bot that added "50" with the (incorrect) "maxspeed:source" key = 
> "default residential speed limit in Australia"  and I think there was 
> consensus in the local community that this was a mistake.
> 
> With remapping some of my local areas, I'm now curious what's best practice 
> in Australia is for tagging maxspeed on residential streets. Specifically...
> 
> a) is it even necessary or desirable to explicitly define maxspeed for every 
> residential way - or should we just presume any highway=residential is 
> maxspeed=50, unless otherwise stated?
> 
> b) if presumptions do exist, should 50 zones on tertiary and unclassified 
> ways be explictly tagged ?
> 
> c) if tagging maxspeed on every street, in respect to source... does a simple 
> source:maxspeed=sign suffice for the "general area" or only for the specific 
> way on which the sign is placed?  I notice these residential 50 speed signs 
> are often on tertiary streets, or gateway points into general residential 
> areas.  Side-streets obviously share the 50 limit, but are mostly not 
> signposted. Do we need a new standard source value like 
> source:maxspeed=implied for the side streets ?
> 
> Sorry if I'm re-covering old ground - I'm just not sure where it was left... 
> if anywhere!
> 
> Thanks in advance.. BJ
> 
> 
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Re: [talk-au] maxspeed - best practice?

[Leon Kernan]

Most software will make assumptions about the max speed based on road type
if it's not specified (for better or worse).
Having it recorded is still the best way if known though.

Also today, Vicroads has announced that speed zones will be changing
around Victoria again. Getting rid of 70's and 90's this time.
Keeping up with the changes is a full time job.

On Tue, Aug 14, 2012 at 4:44 PM, Ian Sergeant  wrote:

> Hi,
>
> a) The thing is, if you don't tag maxspeed=50, then how do tell a
> residential road that is known to be maxspeed=50, against one that is just
> un-surveyed, and might be maxspeed=30,40 or 60?
>
> c) source:maxspeed=sign is clearly correct if there is a sign. If you've
> surveyed around an area, and there isn't a sign, personally I'd tag
> source:maxspeed=survey.  The alternative here, would be
> source:maxspeed=default or some such, but given our history of tagging
> "site unseen".   It  I think this is best avoided. Same goes for
> source=implied for the same reason.  If you've visited and determined the
> speed limit, it is a survey.   maxspeed=local_knowledge if you drive around
> the residential streets in your area all the time, and you just know they
> are all 50km/h.
>
> Just an aside,  a simple case study in presumptions.  Probably the most
> popular OSM open source router is OSRM.  The speedprofiles for that project
> you can see here
>
> https://github.com/DennisOSRM/Project-OSRM/blob/master/speedprofile.ini
>
> I believe OSRM will use a maxspeed on a street if it finds one, so once
> you start marking maxspeeds it makes sense to mark others around them,
> otherwise a maxspeed=40 road will become a preferred road over other
> residentials and secondaries.
>
> I'm sure the motivation for tagging all residentials as maxspeed=50 was
> partly an attempt to address this issue.
>
> Of course, there is a good argument for this being fixed in OSRM, or in
> post-processing the AU data, etc.
>
> Ian.
>
>
> On 14 August 2012 15:30, Ben Johnson  wrote:
>
>> In regards to residential areas - I remember last year there was some
>> talk about the bot that added "50" with the (incorrect) "maxspeed:source"
>> key = "default residential speed limit in Australia"  and I think there was
>> consensus in the local community that this was a mistake.
>>
>> With remapping some of my local areas, I'm now curious what's best
>> practice in Australia is for tagging maxspeed on residential streets.
>> Specifically...
>>
>> a) is it even necessary or desirable to explicitly define maxspeed for
>> every residential way - or should we just presume any highway=residential
>> is maxspeed=50, unless otherwise stated?
>>
>> b) if presumptions do exist, should 50 zones on tertiary and unclassified
>> ways be explictly tagged ?
>>
>> c) if tagging maxspeed on every street, in respect to source... does a
>> simple source:maxspeed=sign suffice for the "general area" or only for the
>> specific way on which the sign is placed?  I notice these residential 50
>> speed signs are often on tertiary streets, or gateway points into general
>> residential areas.  Side-streets obviously share the 50 limit, but are
>> mostly not signposted. Do we need a new standard source value like
>> source:maxspeed=implied for the side streets ?
>>
>> Sorry if I'm re-covering old ground - I'm just not sure where it was
>> left... if anywhere!
>>
>> Thanks in advance.. BJ
>>
>>
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>
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Re: [talk-au] maxspeed - best practice?

[Ian Sergeant]

On 14 August 2012 19:37, Michael James  wrote:


> 2. Guidelines for highway=residential and highway=unclassified
> The guidelines http://wiki.openstreetmap.org/wiki/Key:highway
> give the direction that if houses are on the side of a minor road then
> it should be tagged residential however on the edges of towns and cities
> you can have such streets as per OSM's definition but they will fail to
> fulfill the definition as given in Australian law for an Urban Road and
> thus not have a default of 50kph
>
>
As you point out, there isn't a 1-to-1 correspondence between
highway=residential and the default 50km/h speed limit.  Therefore, we
can't rely on an automated rule, and therefore we have to tag maxspeed to
have an accurate database of speeds.


> tag if signed
> maxspeedsource=sign
>
> tag if not signed and satisfies the definition
> maxspeedsource=built_up_area
>
>
Please use:

source:maxspeed=

as is the convention.

Thanks,
Ian.
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Re: [talk-au] maxspeed - best practice?

[Michael James]

On 08/14/2012 03:30 PM, Ben Johnson wrote:
> In regards to residential areas - I remember last year there was some
> talk about the bot that added "50" with the (incorrect)
> "maxspeed:source" key = "default residential speed limit in Australia" 
> and I think there was consensus in the local community that this was a
> mistake.
> 
> With remapping some of my local areas, I'm now curious what's best
> practice in Australia is for tagging maxspeed on residential streets.
> Specifically...
> 
> a) is it even necessary or desirable to explicitly define maxspeed for
> every residential way - or should we just presume any
> highway=residential is maxspeed=50, unless otherwise stated?

What are we singling out highway=residential?

This is where I want to enter the debate as the whole thinking before
was just wrong as far as what the legislation actually says and what the
map uses as tags for roads.

1. The law :-
25 Speed limit elsewhere
(1) If a speed limit sign does not apply to a length of road and the
length of road is not in a speed limited area, school zone or shared
zone, the speed limit applying to a driver for the length of road is the
default speed limit.
(2) The default speed limit applying to a driver for a length of
road is—
(a) for a road in a built-up area—50km/h; or
(b) for a road that is not in a built-up area—100km/h.

Dictionary entry :-
built-up area, in relation to a length of road, means an area in
which either of the following is present for a distance of at
least 500m or, if the length of road is shorter than 500m, for
the whole road—
(a) buildings, not over 100m apart, on land next to the road;
(b) street lights not over 100m apart.

Note that there is no mention of the word residential in the law

2. Guidelines for highway=residential and highway=unclassified
The guidelines http://wiki.openstreetmap.org/wiki/Key:highway
give the direction that if houses are on the side of a minor road then
it should be tagged residential however on the edges of towns and cities
you can have such streets as per OSM's definition but they will fail to
fulfill the definition as given in Australian law for an Urban Road and
thus not have a default of 50kph

So when should it be tagged ?

In my opinion you should only tag ways that are either signed posted and
you tag it with the figure given and appropriate source ref

Alternatively if you have observed that a street satisfies the
definition given in the road rules for the default to apply then tag it
as such and give the source as built_up_area

tag if signed
maxspeedsource=sign

tag if not signed and satisfies the definition
maxspeedsource=built_up_area

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Re: [talk-au] maxspeed - best practice?

[Ian Sergeant]

Hi,

a) The thing is, if you don't tag maxspeed=50, then how do tell a
residential road that is known to be maxspeed=50, against one that is just
un-surveyed, and might be maxspeed=30,40 or 60?

c) source:maxspeed=sign is clearly correct if there is a sign. If you've
surveyed around an area, and there isn't a sign, personally I'd tag
source:maxspeed=survey.  The alternative here, would be
source:maxspeed=default or some such, but given our history of tagging
"site unseen".   It  I think this is best avoided. Same goes for
source=implied for the same reason.  If you've visited and determined the
speed limit, it is a survey.   maxspeed=local_knowledge if you drive around
the residential streets in your area all the time, and you just know they
are all 50km/h.

Just an aside,  a simple case study in presumptions.  Probably the most
popular OSM open source router is OSRM.  The speedprofiles for that project
you can see here

https://github.com/DennisOSRM/Project-OSRM/blob/master/speedprofile.ini

I believe OSRM will use a maxspeed on a street if it finds one, so once you
start marking maxspeeds it makes sense to mark others around them,
otherwise a maxspeed=40 road will become a preferred road over other
residentials and secondaries.

I'm sure the motivation for tagging all residentials as maxspeed=50 was
partly an attempt to address this issue.

Of course, there is a good argument for this being fixed in OSRM, or in
post-processing the AU data, etc.

Ian.

On 14 August 2012 15:30, Ben Johnson  wrote:

> In regards to residential areas - I remember last year there was some talk
> about the bot that added "50" with the (incorrect) "maxspeed:source" key =
> "default residential speed limit in Australia"  and I think there was
> consensus in the local community that this was a mistake.
>
> With remapping some of my local areas, I'm now curious what's best
> practice in Australia is for tagging maxspeed on residential streets.
> Specifically...
>
> a) is it even necessary or desirable to explicitly define maxspeed for
> every residential way - or should we just presume any highway=residential
> is maxspeed=50, unless otherwise stated?
>
> b) if presumptions do exist, should 50 zones on tertiary and unclassified
> ways be explictly tagged ?
>
> c) if tagging maxspeed on every street, in respect to source... does a
> simple source:maxspeed=sign suffice for the "general area" or only for the
> specific way on which the sign is placed?  I notice these residential 50
> speed signs are often on tertiary streets, or gateway points into general
> residential areas.  Side-streets obviously share the 50 limit, but are
> mostly not signposted. Do we need a new standard source value like
> source:maxspeed=implied for the side streets ?
>
> Sorry if I'm re-covering old ground - I'm just not sure where it was
> left... if anywhere!
>
> Thanks in advance.. BJ
>
>
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