Re: [Talk-us] Prima Facie Speed Limits

[Paul Johnson]

I think in previous situations where this has come up on this list and the
IRC networks was that explicit tagging plus explanatory note is better than
what the Germans are doing for zonal speeds.

On Tue, Sep 16, 2014 at 9:39 AM, Tod Fitch  wrote:

> On Sep 16, 2014, at 12:44 AM, Martin Koppenhoefer wrote:
> > PS: one remark to "California vehicle code 22352"
> > This apparently stands for all kind of prima facie limits in California,
> IMHO you could also use something more specific like "US:CA:school" where
> "US:CA" would be a short form for
> > "California vehicle code 22352" and "school" one of the cases described
> in this code (context). Would also be nice to document these here:
> http://wiki.openstreetmap.org/wiki/Key:source:maxspeed
> >
>
> On Sep 13, 2014, at 8:34 PM, Paul Johnson wrote:
> > Is it maxspeed:source or source:maxspeed?  Also, I'd rather see an
> explanation than a jumbled pseudokey, aka "default speed limit for unposted
> streets in California"
> >
>
> On Sun, Sep 14, 2014 at 6:52 AM, Tod Fitch  wrote:
> > The jumbled pseudokey value "us:ca:residential" was inspired by
> http://wiki.openstreetmap.org/wiki/Key:source:maxspeed used elsewhere in
> the world (e.g. "source:maxspeed=DE:urban"). But I would be happy with
> default speed limit for unposted streets in California", or a shorter
> string like "California vehicle code 22352".
>
> Which will it be? The wiki page for source:maxspeed
> http://wiki.openstreetmap.org/wiki/Key:source:maxspeed#Howto_tag says:
>
> > Howto tag
> >
> > See also: Speed limits
> >   • sign (where the speed limit is defined by a numeric sign.)
> >   • markings (where the speed limit is defined by painted road
> markings.)
> >   • : (where the speed limit is defined by a
> particular context, for example urban/rural/motorway/etc.)
>
> While neither Martin's nor Paul's suggestion exactly match the wiki,
> Martin's is closer.
>
> I don't have strong opinions but would like agreement between more than
> one other person and myself. :)
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Re: [Talk-us] Prima Facie Speed Limits

[Tod Fitch]

On Sep 16, 2014, at 12:44 AM, Martin Koppenhoefer wrote:
> PS: one remark to "California vehicle code 22352"
> This apparently stands for all kind of prima facie limits in California, IMHO 
> you could also use something more specific like "US:CA:school" where "US:CA" 
> would be a short form for 
> "California vehicle code 22352" and "school" one of the cases described in 
> this code (context). Would also be nice to document these here: 
> http://wiki.openstreetmap.org/wiki/Key:source:maxspeed
> 

On Sep 13, 2014, at 8:34 PM, Paul Johnson wrote:
> Is it maxspeed:source or source:maxspeed?  Also, I'd rather see an 
> explanation than a jumbled pseudokey, aka "default speed limit for unposted 
> streets in California"
> 

On Sun, Sep 14, 2014 at 6:52 AM, Tod Fitch  wrote:
> The jumbled pseudokey value "us:ca:residential" was inspired by 
> http://wiki.openstreetmap.org/wiki/Key:source:maxspeed used elsewhere in the 
> world (e.g. "source:maxspeed=DE:urban"). But I would be happy with default 
> speed limit for unposted streets in California", or a shorter string like 
> "California vehicle code 22352".

Which will it be? The wiki page for source:maxspeed 
http://wiki.openstreetmap.org/wiki/Key:source:maxspeed#Howto_tag says:

> Howto tag
> 
> See also: Speed limits
>   • sign (where the speed limit is defined by a numeric sign.)
>   • markings (where the speed limit is defined by painted road markings.)
>   • : (where the speed limit is defined by a 
> particular context, for example urban/rural/motorway/etc.)

While neither Martin's nor Paul's suggestion exactly match the wiki, Martin's 
is closer.

I don't have strong opinions but would like agreement between more than one 
other person and myself. :) 
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Re: [Talk-us] Prima Facie Speed Limits

[Martin Koppenhoefer]

2014-09-16 7:27 GMT+02:00 Greg Morgan :

> Woot! Woot!  If you are adding a speed limit to a node where a sign is
> located and if you add traffic_sign="maxspeed" along with your maxspeed="25
> mph", then JOSM will show you a cute little sign verses a blue dot.
> http://www.openstreetmap.org/node/147417922
>


I'm doing this and also adding traffic_sign=maxspeed to make clear that it
is a sign position. There is also an additional style for josm to display
the actual sign with the correct number (currently just for kph limits),
feel free to extend this for mph (eventually with the typical sign you have
over there):
http://josm.openstreetmap.de/wiki/Styles
http://josm.openstreetmap.de/josmfile?page=Styles/MaxspeedIcons&zip=1  (you
don't have to download it here to use it, you can activate this from inside
josm via preferences, styles)

cheers,
Martin

PS: one remark to "California vehicle code 22352"
This apparently stands for all kind of prima facie limits in California,
IMHO you could also use something more specific like "US:CA:school" where
"US:CA" would be a short form for
"California vehicle code 22352" and "school" one of the cases described in
this code (context). Would also be nice to document these here:
http://wiki.openstreetmap.org/wiki/Key:source:maxspeed
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Re: [Talk-us] Prima Facie Speed Limits

[Greg Morgan]

On Mon, Sep 15, 2014 at 12:37 PM, Tod Fitch  wrote:

>
> I've been off on other things so I haven't done more than make sure that
> the roads tagged with maxspeed=* that I have done in my area also have a
> source:maxspeed=sign. I think I am comfortable enough with this discussion
> thread that I will add maxspeed="25 mph" and source:maxspeed="California
> vehicle code 22352" to the unsigned residential roads I have surveyed.
>

Woot! Woot!  If you are adding a speed limit to a node where a sign is
located and if you add traffic_sign="maxspeed" along with your maxspeed="25
mph", then JOSM will show you a cute little sign verses a blue dot.
http://www.openstreetmap.org/node/147417922
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Re: [Talk-us] Prima Facie Speed Limits

[Tod Fitch]

On Sep 15, 2014, at 1:09 AM, Paul Johnson wrote:

> 
> On Sun, Sep 14, 2014 at 6:52 AM, Tod Fitch  wrote:
> maxspeed:source=* was a "thinko" (kind of like a typo but different part of 
> the body). :)
> 
> OK, probably, but it does sort nicely in JOSM.  Either way, feel free to fix 
> my mistagging on this...I've used maxpseed:source=* on a few counties now and 
> if I got the key backwards, feel free to fix.  I'm not going to argue over 
> extremely minor semantics like this.

Interesting. I happened upon source:maxspeed=* and found it in the wiki so went 
with it and there are over 455,000 uses of that tag. But there are over 22,000 
occurrences of maxspeed:source=* which is quite a high number too. Of those 
9,301 are maxspeed:source=default␣residential␣speed␣limit␣in␣Australia so it 
looks like the use is global and that taggers outside of the US are also 
dealing with default or prima facie speed limits.

My take on the opinions in this thread are:

1. maxspeed=* should have a speed value that is of use to a router or 
navigation aid. So a number (for KPH) or number with " MPH" suffix are greatly 
preferred over things like "maxspeed=unposted".

2. The only real way to get a maxspeed=* value is by survey. Even if the 
jurisdiction has a default speed limit for the type of road, any specific road 
may be signed to some other speed. And, in general, you can't see signs in 
satellite imagery. (Exception in California and perhaps elsewhere: Occasionally 
the speed limit is painted on the pavement and that can be seen in satellite 
imagery.)

3. A source:maxspeed=* tag should accompany any maxspeed=* tag indicating the 
authority. Usually that will be source:maxspeed=sign. Since this tag is for 
human documentation purposes and probably will not have a software based data 
consumer values can be something agreed to by the taggers in the area. For 
unsigned roads things like source:maxspeed=DE:urban seems to work for German 
taggers, but something like source:maxspeed="California vehicle code 22352" 
makes it easy for anyone to do a web search and determine the criteria. 
source:maxspeed=survey is fairly widely used but that does not say if the 
maxspeed was from a sign or a jurisdictional default so I would avoid using it.

4. There are unsigned roads where the jurisdictional boundaries are unclear and 
the jurisdictions in question have different default speed limits. So the 
actual speed limit is not clear to the tagger doing the survey. (Neither is it 
clear for drivers on that road which can lead to issues in enforcement but that 
is not on topic.) In that case the maxspeed=* value is unknown and the tag 
should not be used as it adds no value for the intended data consumers. But we 
want some way to show that the road has been surveyed and the speed is really 
unknown on the ground not just unknown in the OSM database. I think a fixme=* 
tag with explanation in the issue would handle that.

I've been off on other things so I haven't done more than make sure that the 
roads tagged with maxspeed=* that I have done in my area also have a 
source:maxspeed=sign. I think I am comfortable enough with this discussion 
thread that I will add maxspeed="25 mph" and source:maxspeed="California 
vehicle code 22352" to the unsigned residential roads I have surveyed.

Thanks for the input and discussion!
Tod


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Re: [Talk-us] Prima Facie Speed Limits

[Toby Murray]

On Mon, Sep 15, 2014 at 10:52 AM, Martin Koppenhoefer <
dieterdre...@gmail.com> wrote:

>
> 2014-09-15 16:59 GMT+02:00 Ed Hillsman :
>
>> I agree there is a need to have a way to deal with this. Where I have
>> checked a street, in both directions, for a posted speed limit and found
>> none, I tag the street as maxspeed=unposted, source:maxspeed=survey. This
>> makes it clear that the street has been checked in the field and found not
>> to have a posted speed limit.
>
>
>
> one problem I could see with that approach is that the information density
> in your 2 tags is very low (the "unposted" value doesn't say anything about
> the actual speed limit and the survey-value could be seen as implicit for
> this kind of tag). IMHO putting an actual limit into the maxspeed key is
> valueable, regardless whether this is signposted or an implicit limit,
> because this is the speed information that most drivers on that road will
> be interested in (typically).
>
>
I may have some locational bias on this because as far as I know, Kansas
does not have any default speed limits and it is fairly uncommon to see a
(paved) road without a speed limit sign somewhere along it.

So that being said, I'm a fan of putting a maxspeed= tag on
everything. Leaving it up to data consumers to interpret the thousands of
potential local defaults around the world doesn't seem like a good argument
to me. And yes, in urban areas a maxspeed tag is likely to be less useful
but most of our data consumers aren't going to have a historical, indexed
by time of day archive of user traces to extract realistic data from. And
as far as I am aware, there is no open repository of such information. So a
maxspeed tag is at least a good starting point. I don't see the data
maintenance being any different from most of our other data. If it is
actually used in applications (such as OsmAnd or on Garmin devices) then
any errors are going to be fairly visible to users which leads to feedback
and fixing of data.

Toby
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Re: [Talk-us] Prima Facie Speed Limits

[Martin Koppenhoefer]

2014-09-15 16:59 GMT+02:00 Ed Hillsman :

> I agree there is a need to have a way to deal with this. Where I have
> checked a street, in both directions, for a posted speed limit and found
> none, I tag the street as maxspeed=unposted, source:maxspeed=survey. This
> makes it clear that the street has been checked in the field and found not
> to have a posted speed limit.



one problem I could see with that approach is that the information density
in your 2 tags is very low (the "unposted" value doesn't say anything about
the actual speed limit and the survey-value could be seen as implicit for
this kind of tag). IMHO putting an actual limit into the maxspeed key is
valueable, regardless whether this is signposted or an implicit limit,
because this is the speed information that most drivers on that road will
be interested in (typically).

Cheers,
Martin
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[Talk-us] Prima Facie Speed Limits

[Ed Hillsman]

I agree there is a need to have a way to deal with this. Where I have checked a 
street, in both directions, for a posted speed limit and found none, I tag the 
street as maxspeed=unposted, source:maxspeed=survey. This makes it clear that 
the street has been checked in the field and found not to have a posted speed 
limit.

When I lived in Florida, it was in an area where two municipalities and the 
unincorporated county had jurisdiction over the streets. One city defaulted to 
30 mph for unposted streets. The other, supposedly, defaulted to 25 mph, 
although despite repeated efforts I was never able to find the ordinance or 
regulation that set this. The unincorporated parts of the county defaulted to 
the state's default, which was 30 mph. The locations of the municipal 
boundaries were not accurate in OSM, so I felt uncomfortable tagging a street 
near a boundary with source:maxspeed=City_A_default etc.  So, I decided the 
best way to handle this was the scheme I described above. It records what's on 
the ground, and someone who wants to do something that needs a speed limit 
value can overlay an appropriate boundary or regulation or other default to 
fill in the values that are not clear on the ground.

I face a similar situation here in Albuquerque, where I map in the city 
(default of 25 mph), the county (defaults to the state's 30 mph), and Los 
Ranchos (whose default I haven't been able to ascertain definitively--although 
I haven't made a big effort). 

The maxspeed=unposted renders as an olive drab in 
http://www.itoworld.com/map/5, so this makes it easy for me to see at a glance 
which streets I've checked and which ones I haven't. And, if the larger OSM 
community agrees on a standard way to tag unposted streets, this tagging makes 
it easy and, I hope, unambiguous about which streets need to be retagged. The 
only streets that remain ambiguous then are those that have not been checked 
(which remain untagged for maxspeed), and those that have a different speed 
limit in each direction, with a long-ish stretch in between, leaving it unclear 
where the posted speed limit actually changes (for example, Coal and Lead in 
downtown Albuquerque, where transitions between two-way and one-way status 
compound the ambiguity). In these cases I do not tag the ambiguous section for 
maxspeed.

I guess I should mention that I'm interested in using speed limits (with other 
information) for bicycle routing.

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Re: [Talk-us] Prima Facie Speed Limits

[Martin Koppenhoefer]

I also suggest to add source:maxspeed=sign along with maxspeed=* to ways
with signposted maxspeed (especially when the sign posted speed equals the
default speed, because this will keep those speedlimits in place for the
case that the legislation changes and you'd want to update default speed
limits).

cheers,
Martin
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Re: [Talk-us] Prima Facie Speed Limits

[Paul Johnson]

Wait...
65: Highest posted speed limits in Oregon.
75: Highest speed authorized to ODOT for a posted speed limit (so far,
unused, any paved route using a speed limit higher than 65 MPH is
automatically wrong as of this writing)
88: Open desert/dune speed limit (never posted, rarely enforced)
99: Fastest speed allowed anywhere in Oregon without being potentially
charged as a felony (I narrowly avoided a felony doing 117 in the Oregon
Dunes when Oregon State Police by virtue of my sandrail lacking a speedo
and being from out of state, despite having a GPS I was pretty much
ignoring thanks to it waving around everywhere, until it was time to return
it; Don't Go Faster Than This unless you want to have somewhere between a
Bad Time and Prison Time).

On Mon, Sep 15, 2014 at 3:09 AM, Paul Johnson  wrote:

>
> On Sun, Sep 14, 2014 at 6:52 AM, Tod Fitch  wrote:
>
>> maxspeed:source=* was a "thinko" (kind of like a typo but different part
>> of the body). :)
>>
>
> OK, probably, but it does sort nicely in JOSM.  Either way, feel free to
> fix my mistagging on this...I've used maxpseed:source=* on a few counties
> now and if I got the key backwards, feel free to fix.  I'm not going to
> argue over extremely minor semantics like this.
>
> The jumbled pseudokey value "us:ca:residential" was inspired by
>> http://wiki.openstreetmap.org/wiki/Key:source:maxspeed used elsewhere in
>> the world (e.g. "source:maxspeed=DE:urban"). But I would be happy with
>> "default speed limit for unposted streets in California", or a shorter
>> string like "California vehicle code 22352".
>>
>
> I would actually rather cite the code in question, or when in doubt, the
> source signs.  I'll personally vouch for Oklahoma zone speeds (if they're
> 45 or, rarely 35, for county; or 25 for pretty much all of a minor town,
> assuming the state road leading into it has the appropriate stepdowns.)
>
> That said, all of Oregon could be tagged as the following, in MPH, if not
> otherwise tagged:
>
> 3: ODOT scales
> 5: ODOT rest areas and scales.
> 10: Longer ramps in ODOT rest areas and scales.
> 15: Alleyways.
> 15-50: Variable speed zones within urban Portland.
> 20: School zones when flashing or children present.
> 25: Residential ways.
> 30-45: Suburban arterials
> 45: Expressways (trunk) unless otherwise posted (rare, there may be some
> inaccurate NE2 trunks existing, but I know Salem Parkway and Bend Parkway
> are 45s)
> 50: ALL urban freeways except I 405 and I 5 near central Portland (which
> are variable 15-50)
> 55: Suburban freeways, almost all rural highways.
> 60: I5 in Salem (IIRC) and pretty close to nowhere else.
> 65: Extremely rural freeway.
>
> In any rate, maxspeed in Oregon can consider ODOT ORCA a valid source
> under Oregon's sunshine laws (which means, to the best of my understanding,
> every public way in Oregon should have a maxpseed based on the above or
> what is in ODOT ORCA.
> http://www.oregon.gov/ODOT/hwy/traffic-roadway/Pages/speed_zone_program.aspx
>  Anything outside the above chart probably should specifically tag the
> traffic signs involved, since 100% of speed limits on public roads are
> controlled by ODOT.
>
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Re: [Talk-us] Prima Facie Speed Limits

[Paul Johnson]

On Sun, Sep 14, 2014 at 6:52 AM, Tod Fitch  wrote:

> maxspeed:source=* was a "thinko" (kind of like a typo but different part
> of the body). :)
>

OK, probably, but it does sort nicely in JOSM.  Either way, feel free to
fix my mistagging on this...I've used maxpseed:source=* on a few counties
now and if I got the key backwards, feel free to fix.  I'm not going to
argue over extremely minor semantics like this.

The jumbled pseudokey value "us:ca:residential" was inspired by
> http://wiki.openstreetmap.org/wiki/Key:source:maxspeed used elsewhere in
> the world (e.g. "source:maxspeed=DE:urban"). But I would be happy with
> "default speed limit for unposted streets in California", or a shorter
> string like "California vehicle code 22352".
>

I would actually rather cite the code in question, or when in doubt, the
source signs.  I'll personally vouch for Oklahoma zone speeds (if they're
45 or, rarely 35, for county; or 25 for pretty much all of a minor town,
assuming the state road leading into it has the appropriate stepdowns.)

That said, all of Oregon could be tagged as the following, in MPH, if not
otherwise tagged:

3: ODOT scales
5: ODOT rest areas and scales.
10: Longer ramps in ODOT rest areas and scales.
15: Alleyways.
15-50: Variable speed zones within urban Portland.
20: School zones when flashing or children present.
25: Residential ways.
30-45: Suburban arterials
45: Expressways (trunk) unless otherwise posted (rare, there may be some
inaccurate NE2 trunks existing, but I know Salem Parkway and Bend Parkway
are 45s)
50: ALL urban freeways except I 405 and I 5 near central Portland (which
are variable 15-50)
55: Suburban freeways, almost all rural highways.
60: I5 in Salem (IIRC) and pretty close to nowhere else.
65: Extremely rural freeway.

In any rate, maxspeed in Oregon can consider ODOT ORCA a valid source under
Oregon's sunshine laws (which means, to the best of my understanding, every
public way in Oregon should have a maxpseed based on the above or what is
in ODOT ORCA.
http://www.oregon.gov/ODOT/hwy/traffic-roadway/Pages/speed_zone_program.aspx
 Anything outside the above chart probably should specifically tag the
traffic signs involved, since 100% of speed limits on public roads are
controlled by ODOT.
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Re: [Talk-us] Prima Facie Speed Limits

[Tod Fitch]

maxspeed:source=* was a "thinko" (kind of like a typo but different part of the 
body). :)

The jumbled pseudokey value "us:ca:residential" was inspired by 
http://wiki.openstreetmap.org/wiki/Key:source:maxspeed used elsewhere in the 
world (e.g. "source:maxspeed=DE:urban"). But I would be happy with "default 
speed limit for unposted streets in California", or a shorter string like 
"California vehicle code 22352".


On Sep 13, 2014, at 9:34 PM, Paul Johnson wrote:

> On Mon, Sep 8, 2014 at 4:27 PM, Tod Fitch  wrote:
> Thus far I've only applied the maxspeed tag to roads with a posted speed 
> limit. But here in California most residential roads are not posted, instead 
> there is a state wide prima facie limit: 
> http://www.dmv.ca.gov/pubs/vctop/d11/vc22352.htm
> I am considering tagging the unsigned speed limit on residential roads in my 
> area and am thinking of tagging the authority of the speed with 
> "source:maxspeed=US:CA:residential" based on an extension of the type of 
> things I see at http://wiki.openstreetmap.org/wiki/Key:source:maxspeed
> 
> Is it maxspeed:source or source:maxspeed?  Also, I'd rather see an 
> explanation than a jumbled pseudokey, aka "default speed limit for unposted 
> streets in California"
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Re: [Talk-us] Prima Facie Speed Limits

[Martin Koppenhoefer]

> Il giorno 14/set/2014, alle ore 06:34, Paul Johnson  ha 
> scritto:
> 
> Is it maxspeed:source or source:maxspeed?


"invented" as source:maxspeed and also most used

cheers,
Martin
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Re: [Talk-us] Prima Facie Speed Limits

[Paul Johnson]

I should also add that in the US, it depends wildly on where you are.  In
Oregon, for example, all speed limits on all public roads, regardless of
what government authority actually owns and operates the road, are set by
the Oregon Department of Transportation, period.  Yes, everything from a
parking aisle in a government parking lot, to a service alley in a
neighborhood up to the largest freeway, set by ODOT.

On the other end of the spectrum (as far as I'm aware), you have Oklahoma,
which OklaDOT has overriding authority, but delegates speed limits to local
counties, who generally in turn delegate to local towns and cities, and
generally don't run into problems as long as everyone's in agreement on
what a reasonable speed limit for the local community and highway
conditions are, particularly when it concerns state highways (since
everything state highway and up OklaDOT definitely has control over, and
they greatly prefer to step down the speed in 10 MPH increments to meet the
local town's expectations).

There's a few places where this doesn't always work out, but it's probably
as likely an overlooked stolen sign than deliberate malice on local
jurisdictions parts (such as entering Ramona, OK on County Road W3350 from
the west, the speed limit drops from 45 to 25 with no warning from as long
as I've been aware of the road to as recently as July, but there is
evidence that the sign is just plain missing as there's a few empty posts
heading into town on that rarely used road).
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Re: [Talk-us] Prima Facie Speed Limits

[Paul Johnson]

On Mon, Sep 8, 2014 at 4:55 PM, Greg Morgan  wrote:

>
> I wonder if 15 mph in a school zone and 25 mph in a residential area are
> some sort of federal standard?  The source tag might be useful but not much
> different than other states.
>

Not as far as I'm aware.  Oregon's school zones are always 20.  Oklahoma's
all over the place:  I've seen everything from 5 to 55, though the mode
seems to be 25.  Residential streets also have some spread, many small
towns are somewhere in the 10-20 range, with most of the big cities and
larger towns going with 25.  The mode, however, is 45, since the vast
majority of roads are not posted, and the default speed limit in most
counties, is 45 ("Entering Wagoner County / County Wide Speed Limit 45 MPH
unless otherwise posted") unless a more local jurisdiction overrides it
("SPEED LIMIT 25 unless otherwise posted within Cleveland," "SPEED LIMIT 25
on all residential streets unless otherwise posted in Bartlesville") and a
lot of smaller towns just plain don't bother with more than street names
and only enough stop signs to keep people from blindly running into the
highway through town (except maybe a two-way yield or two, most likely
where Chuck scratched up Billy's new pickup back in '98).
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Re: [Talk-us] Prima Facie Speed Limits

[Paul Johnson]

On Mon, Sep 8, 2014 at 4:27 PM, Tod Fitch  wrote:

> Thus far I've only applied the maxspeed tag to roads with a posted speed
> limit. But here in California most residential roads are not posted,
> instead there is a state wide prima facie limit:
> http://www.dmv.ca.gov/pubs/vctop/d11/vc22352.htm

I am considering tagging the unsigned speed limit on residential roads in
> my area and am thinking of tagging the authority of the speed with
> "source:maxspeed=US:CA:residential" based on an extension of the type of
> things I see at http://wiki.openstreetmap.org/wiki/Key:source:maxspeed


Is it maxspeed:source or source:maxspeed?  Also, I'd rather see an
explanation than a jumbled pseudokey, aka "default speed limit for unposted
streets in California"
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Re: [Talk-us] Prima Facie Speed Limits

[stevea]

Hello Kerry and Greg:

Even though I'm "just" a lay person in this regard, I'm rather 
familiar with the MUTCD (though not at the level of detail of a 
traffic engineer or a professional urban transportation planner).


Any "federal standard" about stop signs being red and eight sided and 
intersections being marked in consistent ways happens because of a 
well-understood scenario, envisioned by the authors of our federal 
Constitution:  states develop such things in an experimental way, 
some solutions are found to be more successful than others, and hence 
emerge, then other states pick up on working solutions and they 
implement them as well.  Sometimes (as with traffic engineering, the 
MUTCD and Interstate Highways), formal standards bodies (like AASHTO) 
craft such statewide standards into something which "resembles" a 
federal standard, but in fact are more like a broad understanding: 
states together coming to agreement independent of the federal 
government.  AASHTO, after all, is a non-profit of professionals, and 
while it is based in Washington, DC, it is not part of the federal 
government.


I say this to underscore my original point:  the distinction between 
what is federal (only those "enumerated powers" specified in the 
Constitution), and what is state (everything else).  Much about this 
continues to be confused in the public mind, (a failure of good 
civics in our public schools?) but the basic facts of this haven't 
changed in over 200 years.  I don't want to get overtly political, 
but it does seem to bear repeating in this context.  Oh, and states 
accepting federal dollars doesn't "override" state's rights, states 
simply give away certain sovereign rights in exchange for the 
dollars.  They don't have to, but that IS the bargain.


In short, states are responsible for traffic laws.  There is some 
overlap between state and federal which has been deliberately crafted 
(Interstate Highways, ICE-TEA funding, MPOs usurping local control 
via federal $...), but the fact of state/local control over 
transportation infrastructure, law and funding remains essentially 
true, until something explicit (e.g. acceptance of federal $) changes 
it.


I don't know what the answers might be regarding prima facie speed 
limits in OSM.  It doesn't seem totally incorrect to put these in, 
but again, I find speed limits in OSM most useful when they designate 
where a sign explicitly specifies what speed limits are where.  "Data 
consumers" (ETA algorithms...) may or may not use such data.  The 
"better" ones might pay attention to them, then use them or ignore 
them based upon even MORE intelligence.  Yet again:  conscientious 
attention to both structured data and code (logic) is warranted.


SteveA
California


Signage standards are contained in the MUTCD (Manual on Uniform 
Traffic Control Devices).  These are standards, not absolute 
requirements, but you will find them followed pretty closely because 
traffic engineers don't like having to explain why they have not 
complied with standards.  Several states have their own version of 
the MUTCD, usually with either a few additions to the MUTCD or even 
by reducing the options of signage.


Kerry Irons

From: Greg Morgan [mailto:dr.kludge...@gmail.com]
Sent: Wednesday, September 10, 2014 9:22 AM
To: stevea
Cc: talk-us@openstreetmap.org
Subject: Re: [Talk-us] Prima Facie Speed Limits


I wonder if 15 mph in a school zone and 25 mph in a residential area 
are some sort of federal standard?  The source tag might be useful 
but not much different than other states.


On Tue, Sep 9, 2014 at 10:31 AM, stevea 
<<mailto:stevea...@softworkers.com>stevea...@softworkers.com> wrote:
The federal government doesn't have anything to say about speed 
limits (in states), as the US Constitution leaves such things to the 
states.


I was thinking more like a stop sign is red and eight sided.  A 
traffic engineer told me that there is a federal standard governing 
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Re: [Talk-us] Prima Facie Speed Limits

[Martin Koppenhoefer]

> Il giorno 10/set/2014, alle ore 20:15, Tod Fitch  ha 
> scritto:
> 
> The more I think about it, tagging each way is a bit like "(incorrect) 
> tagging for the router", basically creating a maintenance headache and 
> cluttering the OSM database with stuff the current router and navigation 
> guidance can use without being changed.


from my experience here, adding the maxspeed source (implicit from setting/ 
explicit from sign) really improves the maintenance situation. Also mapping 
sign positions helps a lot.

cheers,
Martin
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Re: [Talk-us] Prima Facie Speed Limits

[Richard Welty]

On 9/10/14 2:15 PM, Tod Fitch wrote:
> The more I think about it, tagging each way is a bit like "(incorrect) 
> tagging for the router", basically creating a maintenance headache and 
> cluttering the OSM database with stuff the current router and navigation 
> guidance can use without being changed.
>
> But the rule is really for a whole jurisdiction and could be covered with a 
> handful of tags, one for each highway class on the area or relation that 
> describes the administrative area. That would allow for cases like 
> Burlington, Vermont having prima facie limits even if Vermont doesn't (as was 
> mentioned earlier in this thread). And it would allow easy updates if/when 
> that administrative unit changes its laws, only a handful of tags all on one 
> object versus changing potentially thousands of highway objects.
>
the tradeoff is added complexity for the data consumers
who  now have to process the boundary to determine maxspeed.

secondarily, we still need to tag the ways in some manner
(e.g. maxspeed=admin_default or something) so that it's
clear that someone actually was paying attention, because
otherwise (as i think Martin pointed out) the absence of the
tag could mean two different things.

richard

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Re: [Talk-us] Prima Facie Speed Limits

[Tod Fitch]

On Sep 10, 2014, at 10:49 AM, Richard Welty wrote:

> actually one of the most powerful motivators behind
> the widespread adaption of the MUTCD is liability.
> if states and municipalities show they are operating
> in accordance with the MUTCD then they can avoid
> a world of hurt in court. it's why the recent addition
> of a number of bicycle facilities to the MUTCD is a
> big deal, as it makes them suddenly ok for many
> jurisdictions where they weren't before.
> 
> richard

Back to topic: What is the feeling of those on this list about the relative 
merits of marking each way with "maxspeed=*" and 
"source:maxspeed=US:ST:highwayclass" (or some equivalent) versus tagging the 
administrative area(s) with the prima facie speed limits for each class?

The more I think about it, tagging each way is a bit like "(incorrect) tagging 
for the router", basically creating a maintenance headache and cluttering the 
OSM database with stuff the current router and navigation guidance can use 
without being changed.

But the rule is really for a whole jurisdiction and could be covered with a 
handful of tags, one for each highway class on the area or relation that 
describes the administrative area. That would allow for cases like Burlington, 
Vermont having prima facie limits even if Vermont doesn't (as was mentioned 
earlier in this thread). And it would allow easy updates if/when that 
administrative unit changes its laws, only a handful of tags all on one object 
versus changing potentially thousands of highway objects.

Thanks!
Tod
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Re: [Talk-us] Prima Facie Speed Limits

[Richard Welty]

On 9/10/14 9:42 AM, Greg Morgan wrote:
>
> Thanks.  I could not remember the name of the manual.  Although states
> have rights, federal $$dollars$$ and the restrictions attached can
> have a way overriding states rights.
actually one of the most powerful motivators behind
the widespread adaption of the MUTCD is liability.
if states and municipalities show they are operating
in accordance with the MUTCD then they can avoid
a world of hurt in court. it's why the recent addition
of a number of bicycle facilities to the MUTCD is a
big deal, as it makes them suddenly ok for many
jurisdictions where they weren't before.

richard

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Re: [Talk-us] Prima Facie Speed Limits

[Kerry Irons]

Signage standards are contained in the MUTCD (Manual on Uniform Traffic Control 
Devices).  These are standards, not absolute requirements, but you will find 
them followed pretty closely because traffic engineers don’t like having to 
explain why they have not complied with standards.  Several states have their 
own version of the MUTCD, usually with either a few additions to the MUTCD or 
even by reducing the options of signage.

 

 

Kerry Irons

 

From: Greg Morgan [mailto:dr.kludge...@gmail.com] 
Sent: Wednesday, September 10, 2014 9:22 AM
To: stevea
Cc: talk-us@openstreetmap.org
Subject: Re: [Talk-us] Prima Facie Speed Limits

 

 

 

On Tue, Sep 9, 2014 at 10:31 AM, stevea  wrote:

I wonder if 15 mph in a school zone and 25 mph in a residential area are some 
sort of federal standard?  The source tag might be useful but not much 
different than other states.

 

The federal government doesn't have anything to say about speed limits (in 
states), as the US Constitution leaves such things to the states.  

 

I was thinking more like a stop sign is red and eight sided.  A traffic 
engineer told me that there is a federal standard governing how intersections 
are marked, etc.

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Re: [Talk-us] Prima Facie Speed Limits

[Greg Morgan]

On Wed, Sep 10, 2014 at 6:35 AM, Harald Kliems  wrote:

>
> On Wed, Sep 10, 2014 at 3:21 PM, Greg Morgan 
> wrote:
>
>>
>>
>> I was thinking more like a stop sign is red and eight sided.  A traffic
>> engineer told me that there is a federal standard governing how
>> intersections are marked, etc.
>>
>
> You're probably thinking of the Manual on Uniform Traffic Control Devices
> (MUTCD) http://mutcd.fhwa.dot.gov/
>
> Not quite sure how it is relevant to the max speed discussion, though.
>
>  Harald.
>

Harald,

Thanks.  I could not remember the name of the manual.  Although states have
rights, federal $$dollars$$ and the restrictions attached can have a way
overriding states rights.

Gerg
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Re: [Talk-us] Prima Facie Speed Limits

[Harald Kliems]

On Wed, Sep 10, 2014 at 3:21 PM, Greg Morgan  wrote:

>
>
> I was thinking more like a stop sign is red and eight sided.  A traffic
> engineer told me that there is a federal standard governing how
> intersections are marked, etc.
>

You're probably thinking of the Manual on Uniform Traffic Control Devices
(MUTCD) http://mutcd.fhwa.dot.gov/

Not quite sure how it is relevant to the max speed discussion, though.

 Harald.

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Re: [Talk-us] Prima Facie Speed Limits

[Greg Morgan]

On Tue, Sep 9, 2014 at 10:31 AM, stevea  wrote:

>   I wonder if 15 mph in a school zone and 25 mph in a residential area
> are some sort of federal standard?  The source tag might be useful but not
> much different than other states.
>
>
> The federal government doesn't have anything to say about speed limits (in
> states), as the US Constitution leaves such things to the states.
>

I was thinking more like a stop sign is red and eight sided.  A traffic
engineer told me that there is a federal standard governing how
intersections are marked, etc.
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Re: [Talk-us] Prima Facie Speed Limits

[Martin Koppenhoefer]

2014-09-09 17:47 GMT+02:00 Martijn van Exel :

> I'm of the opinion that wherever the speed limit is just the default for
> that road class, it should not need to be posted at all. Any data user can
> then infer limits.



I don't know how this is handled in the US, but in Europe you will
definitely need explicit speed limits because there is no road class in OSM
that represents the needed properties. In Germany and Italy (and likely in
many other countries as well) for instance there is a distinction between
"inside settlement" and "outside settlement". Now not all residential roads
are inside a closed settlement, and not every settlement is considered a
settlement for the purpose of this law. The actual limits get set by the
city_limit signs, which do not correspond to actual settlement boundaries
but are put where the traffic planners think you should slow down (i.e.
even if we mapped places in osm in all instances as areas, this place area
would not correspond to the area with "urban" city limit).

Besides this, there is another issue: when a key in osm is missing, you
will not know if it is missing (here maxspeed), you will not know if it is
missing or if the default should apply.

Both are IMHO strong arguments to map also "default" (i.e. implicit, not
sign-posted) speed limits, while the dataconsumers (e.g. routers), will of
course need default values for road classes, especially for the cases of
missing maxspeed information.

cheers,
Martin
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Re: [Talk-us] Prima Facie Speed Limits

[Martijn van Exel]

Thanks for clarifying, Tod. For ETA the congested urban use case is much
more challenging to get right, and much more likely to rely on an dynamic
ETA estimate. If you're on a multi-hour trip, you're more likely to have
scoped out your travel time before you leave and planned accordingly, and
if that estimate is off by perhaps 30 minutes, that's usually not the end
of the world. For many phone navigation apps, the commuting use case is
front and center, because the route people take to and from work will
depend a lot on live traffic conditions. (Remember Waze's slogan -
outsmarting traffic together, or something). So it's really navigation and
ETA going hand in hand to deliver the user the optimal way to work or home.

On Tue, Sep 9, 2014 at 3:00 PM, Tod Fitch  wrote:

> Yes, a "pretty small use case" at somewhere around 10,000,000 trips per
> year on I-5 through the central valley of California. Or 9,000,000 trips
> per year each way on I-8 across the desert to the Arizona border.
>
> On your daily commute, you may not need help navigating so much as you
> want accurate real time information about which routes are moving well
> compared to others. For me, trip planning and using a navigation device is
> not for local driving (I mostly use OsmAnd for local driving to help me
> find errors in OSM data) as much as for getting me to places I don't go on
> a daily basis. You could say it is a pretty small use case as most people
> don't drive to or through unfamiliar places everyday, but it is probably
> the biggest use case for a nav system there is.
>
> Cheers,
> Tod
>
> On Sep 9, 2014, at 1:17 PM, Martijn van Exel wrote:
>
> Agreed - that's a pretty small use case, relatively, though.
>
> On Tue, Sep 9, 2014 at 1:38 PM, Tod Fitch  wrote:
>
>> Historical and live speed profiles are pretty much required for trip
>> planning in congested urban areas, but for those of us who drive close to
>> the speed limit and make long trips on relatively uncrowded rural freeways,
>> travel time estimates based on posted (or prima facie) speeds are a good
>> approximation to reality. I travel between northern California and southern
>> Arizona a lot. The distance is about 1,300 kilometers and only a small
>> fraction of that is congested urban freeways (especially if I decide, as I
>> usually do, to avoid Los Angeles). OsmAnd with its knowledge of actual
>> posted speed limits (many entered by me) does a very good job at predicting
>> my arrival time.
>>
>>
>
>
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Re: [Talk-us] Prima Facie Speed Limits

[Tod Fitch]

Yes, a "pretty small use case" at somewhere around 10,000,000 trips per year on 
I-5 through the central valley of California. Or 9,000,000 trips per year each 
way on I-8 across the desert to the Arizona border.

On your daily commute, you may not need help navigating so much as you want 
accurate real time information about which routes are moving well compared to 
others. For me, trip planning and using a navigation device is not for local 
driving (I mostly use OsmAnd for local driving to help me find errors in OSM 
data) as much as for getting me to places I don't go on a daily basis. You 
could say it is a pretty small use case as most people don't drive to or 
through unfamiliar places everyday, but it is probably the biggest use case for 
a nav system there is.

Cheers,
Tod

On Sep 9, 2014, at 1:17 PM, Martijn van Exel wrote:

> Agreed - that's a pretty small use case, relatively, though.
> 
> On Tue, Sep 9, 2014 at 1:38 PM, Tod Fitch  wrote:
> Historical and live speed profiles are pretty much required for trip planning 
> in congested urban areas, but for those of us who drive close to the speed 
> limit and make long trips on relatively uncrowded rural freeways, travel time 
> estimates based on posted (or prima facie) speeds are a good approximation to 
> reality. I travel between northern California and southern Arizona a lot. The 
> distance is about 1,300 kilometers and only a small fraction of that is 
> congested urban freeways (especially if I decide, as I usually do, to avoid 
> Los Angeles). OsmAnd with its knowledge of actual posted speed limits (many 
> entered by me) does a very good job at predicting my arrival time.
> 
> 

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Re: [Talk-us] Prima Facie Speed Limits

[Martijn van Exel]

Agreed - that's a pretty small use case, relatively, though.

On Tue, Sep 9, 2014 at 1:38 PM, Tod Fitch  wrote:

> Historical and live speed profiles are pretty much required for trip
> planning in congested urban areas, but for those of us who drive close to
> the speed limit and make long trips on relatively uncrowded rural freeways,
> travel time estimates based on posted (or prima facie) speeds are a good
> approximation to reality. I travel between northern California and southern
> Arizona a lot. The distance is about 1,300 kilometers and only a small
> fraction of that is congested urban freeways (especially if I decide, as I
> usually do, to avoid Los Angeles). OsmAnd with its knowledge of actual
> posted speed limits (many entered by me) does a very good job at predicting
> my arrival time.
>
> On Sep 9, 2014, at 11:48 AM, Martijn van Exel wrote:
>
> > There's a functional difference between speed limits and the actual
> speed driven. For ETA prediction, speed limit data is not all that useful -
> detailed historical and live speed profiles are. That is not data that is
> in OSM (or should be). The speed limits are mostly useful for alerting
> drivers they may be driving too fast. For a system like that to be feasible
> you will need comprehensive posted speed limit coverage, which OSM
> currently does not have.
> >
> > Martijn
> >
>
>
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Re: [Talk-us] Prima Facie Speed Limits

[Tod Fitch]

Historical and live speed profiles are pretty much required for trip planning 
in congested urban areas, but for those of us who drive close to the speed 
limit and make long trips on relatively uncrowded rural freeways, travel time 
estimates based on posted (or prima facie) speeds are a good approximation to 
reality. I travel between northern California and southern Arizona a lot. The 
distance is about 1,300 kilometers and only a small fraction of that is 
congested urban freeways (especially if I decide, as I usually do, to avoid Los 
Angeles). OsmAnd with its knowledge of actual posted speed limits (many entered 
by me) does a very good job at predicting my arrival time.

On Sep 9, 2014, at 11:48 AM, Martijn van Exel wrote:

> There's a functional difference between speed limits and the actual speed 
> driven. For ETA prediction, speed limit data is not all that useful - 
> detailed historical and live speed profiles are. That is not data that is in 
> OSM (or should be). The speed limits are mostly useful for alerting drivers 
> they may be driving too fast. For a system like that to be feasible you will 
> need comprehensive posted speed limit coverage, which OSM currently does not 
> have.
> 
> Martijn
> 


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Re: [Talk-us] Prima Facie Speed Limits

[Martijn van Exel]

There's a functional difference between speed limits and the actual speed
driven. For ETA prediction, speed limit data is not all that useful -
detailed historical and live speed profiles are. That is not data that is
in OSM (or should be). The speed limits are mostly useful for alerting
drivers they may be driving too fast. For a system like that to be feasible
you will need comprehensive posted speed limit coverage, which OSM
currently does not have.

Martijn

On Tue, Sep 9, 2014 at 12:38 PM, Tod Fitch  wrote:

> On Sep 9, 2014, at 10:31 AM, stevea wrote:
>
> I wonder if 15 mph in a school zone and 25 mph in a residential area are
> some sort of federal standard?  The source tag might be useful but not much
> different than other states.
>
>
> The federal government doesn't have anything to say about speed limits (in
> states), as the US Constitution leaves such things to the states.  An
> exception is on federal land, such as national parks or BLM land, where
> specific parts of the US Code regarding speed limits DO apply.  This is why
> you can get a speeding or parking ticket at Yosemite, but you won't deal
> with California to fight it or pay the fine:  Yosemite is not part of
> California.  Surrounded by it, yes.  Part of it, no.
>
> My GPS (a still-tough Garmin 60 CSx) does an excellent job of calculating
> Estimated Time of Arrival (ETA) when routing.  It does so by assuming speed
> limits for all road segments in the current route and guesses I'll travel
> at those speeds.  This is done without assigning a speed limit to each and
> every road segment, instead implementing a simple table lookup (freeway:
> assume 65 MPH, residential:  assume 25 MPH...).  This is a highly efficient
> solution that keeps the data light and the calculation short and simple, so
> it quickly produces an accurate ETA result.
>
> Though I don't find incorrect (or offensive) the suggestion of tagging* prima
> facie* limits with the tagging syntax specified, I find speed limit
> tagging to be most useful where there are posted signs with a specific
> number.  That's just me, though.
>
> SteveA
> California
>
>
> The DVD map based nav system in my 10 year old car makes the same
> assumption about speeds based on its three classes of roads. It had wildly
> incorrect times until I configured it for California speeds. Now it does a
> reasonable job at estimating travel times on its selected route if I am in
> California. But typical rural speed freeway speeds vary considerably from
> state to state and for longer trips the times are still quite a bit off.
> Assumed values are not as good as actual values. (And my car nav system
> always tries for the slow way to the southern SF bay are apparently
> ignoring that CA 152 exists until I actually make the turn on to it from
> I-5 when it realizes that my way is both shorter and faster than the route
> it picked, so it has other problems.)
>
> A while back I suggested that prima facie speed limits tags be put the
> boundary area/relation for administrative areas. So the relation for
> California could specify something like "prima_facie:maxspeed:motorway=65
> MPH". This would be a simple to implement scheme with relatively few
> entries in OSM and be easy to update in the rare situation where the law
> changes. It could also allow for city or county rules to be specified.
> Routing algorithms could discover the appropriate assumed speeds for any
> class of road in an area buy looking at the enclosing administrative
> boundaries and the tags on those boundaries.
>
> But that suggestion was met with a pretty cold response by the tagging
> mail list. Instead a multitude of roads in Europe and elsewhere are being
> tagged with the prima facie speeds and having a source:maxspeed tag to
> explain it. My suggestion in this thread will contributed to that so I
> admit it is not my first choice.
>
> Tod
>
>
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Re: [Talk-us] Prima Facie Speed Limits

[Tod Fitch]

On Sep 9, 2014, at 10:31 AM, stevea wrote:

>>> I wonder if 15 mph in a school zone and 25 mph in a residential area are 
>>> some sort of federal standard?  The source tag might be useful but not much 
>>> different than other states.
> 
> The federal government doesn't have anything to say about speed limits (in 
> states), as the US Constitution leaves such things to the states.  An 
> exception is on federal land, such as national parks or BLM land, where 
> specific parts of the US Code regarding speed limits DO apply.  This is why 
> you can get a speeding or parking ticket at Yosemite, but you won't deal with 
> California to fight it or pay the fine:  Yosemite is not part of California.  
> Surrounded by it, yes.  Part of it, no.
> 
> My GPS (a still-tough Garmin 60 CSx) does an excellent job of calculating 
> Estimated Time of Arrival (ETA) when routing.  It does so by assuming speed 
> limits for all road segments in the current route and guesses I'll travel at 
> those speeds.  This is done without assigning a speed limit to each and every 
> road segment, instead implementing a simple table lookup (freeway:  assume 65 
> MPH, residential:  assume 25 MPH...).  This is a highly efficient solution 
> that keeps the data light and the calculation short and simple, so it quickly 
> produces an accurate ETA result.
> 
> Though I don't find incorrect (or offensive) the suggestion of tagging prima 
> facie limits with the tagging syntax specified, I find speed limit tagging to 
> be most useful where there are posted signs with a specific number.  That's 
> just me, though.
> 
> SteveA
> California

The DVD map based nav system in my 10 year old car makes the same assumption 
about speeds based on its three classes of roads. It had wildly incorrect times 
until I configured it for California speeds. Now it does a reasonable job at 
estimating travel times on its selected route if I am in California. But 
typical rural speed freeway speeds vary considerably from state to state and 
for longer trips the times are still quite a bit off. Assumed values are not as 
good as actual values. (And my car nav system always tries for the slow way to 
the southern SF bay are apparently ignoring that CA 152 exists until I actually 
make the turn on to it from I-5 when it realizes that my way is both shorter 
and faster than the route it picked, so it has other problems.)

A while back I suggested that prima facie speed limits tags be put the boundary 
area/relation for administrative areas. So the relation for California could 
specify something like "prima_facie:maxspeed:motorway=65 MPH". This would be a 
simple to implement scheme with relatively few entries in OSM and be easy to 
update in the rare situation where the law changes. It could also allow for 
city or county rules to be specified. Routing algorithms could discover the 
appropriate assumed speeds for any class of road in an area buy looking at the 
enclosing administrative boundaries and the tags on those boundaries.

But that suggestion was met with a pretty cold response by the tagging mail 
list. Instead a multitude of roads in Europe and elsewhere are being tagged 
with the prima facie speeds and having a source:maxspeed tag to explain it. My 
suggestion in this thread will contributed to that so I admit it is not my 
first choice.

Tod

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Re: [Talk-us] Prima Facie Speed Limits

[stevea]

I wonder if 15 mph in a school zone and 25 mph in a residential 
area are some sort of federal standard?  The source tag might be 
useful but not much different than other states.


The federal government doesn't have anything to say about speed 
limits (in states), as the US Constitution leaves such things to the 
states.  An exception is on federal land, such as national parks or 
BLM land, where specific parts of the US Code regarding speed limits 
DO apply.  This is why you can get a speeding or parking ticket at 
Yosemite, but you won't deal with California to fight it or pay the 
fine:  Yosemite is not part of California.  Surrounded by it, yes. 
Part of it, no.


My GPS (a still-tough Garmin 60 CSx) does an excellent job of 
calculating Estimated Time of Arrival (ETA) when routing.  It does so 
by assuming speed limits for all road segments in the current route 
and guesses I'll travel at those speeds.  This is done without 
assigning a speed limit to each and every road segment, instead 
implementing a simple table lookup (freeway:  assume 65 MPH, 
residential:  assume 25 MPH...).  This is a highly efficient solution 
that keeps the data light and the calculation short and simple, so it 
quickly produces an accurate ETA result.


Though I don't find incorrect (or offensive) the suggestion of 
tagging prima facie limits with the tagging syntax specified, I find 
speed limit tagging to be most useful where there are posted signs 
with a specific number.  That's just me, though.


SteveA
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Re: [Talk-us] Prima Facie Speed Limits

[John F. Eldredge]

One street here in Nashville, TN, went for several years without any speed 
limit signs along its three-mile length. Then, one day, it suddenly had signs 
every half-mile or so. I suspect that someone probably argued their way out of 
a speeding ticket on the grounds that there weren't any posted limits. 
Tennessee doesn't have any default speed limits that I am aware of, although 
one can always be cited for "reckless driving".


On September 9, 2014 10:47:24 AM CDT, Martijn van Exel  wrote:
> I'm of the opinion that wherever the speed limit is just the default
> for
> that road class, it should not need to be posted at all. Any data user
> can
> then infer limits.
> 
> Martijn
> 
> On Mon, Sep 8, 2014 at 3:27 PM, Tod Fitch  wrote:
> 
> > Thus far I've only applied the maxspeed tag to roads with a posted
> speed
> > limit. But here in California most residential roads are not posted,
> > instead there is a state wide prima facie limit:
> > http://www.dmv.ca.gov/pubs/vctop/d11/vc22352.htm
> >
> > I am considering tagging the unsigned speed limit on residential
> roads in
> > my area and am thinking of tagging the authority of the speed with
> > "source:maxspeed=US:CA:residential" based on an extension of the
> type of
> > things I see at
> http://wiki.openstreetmap.org/wiki/Key:source:maxspeed
> >
> > How does this sound? Objections? Is there a better way?
> >
> > Thanks!
> > Tod
> >
> >
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> 
> 
> 
> 
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Re: [Talk-us] Prima Facie Speed Limits

[Martijn van Exel]

I'm of the opinion that wherever the speed limit is just the default for
that road class, it should not need to be posted at all. Any data user can
then infer limits.

Martijn

On Mon, Sep 8, 2014 at 3:27 PM, Tod Fitch  wrote:

> Thus far I've only applied the maxspeed tag to roads with a posted speed
> limit. But here in California most residential roads are not posted,
> instead there is a state wide prima facie limit:
> http://www.dmv.ca.gov/pubs/vctop/d11/vc22352.htm
>
> I am considering tagging the unsigned speed limit on residential roads in
> my area and am thinking of tagging the authority of the speed with
> "source:maxspeed=US:CA:residential" based on an extension of the type of
> things I see at http://wiki.openstreetmap.org/wiki/Key:source:maxspeed
>
> How does this sound? Objections? Is there a better way?
>
> Thanks!
> Tod
>
>
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Re: [Talk-us] Prima Facie Speed Limits

[Tod Fitch]

On Sep 9, 2014, at 6:10 AM, Andrew Guertin wrote:

> On 09/08/2014 05:27 PM, Tod Fitch wrote:
>> [...]
>> instead there is a state wide prima facie limit:
>> "source:maxspeed=US:CA:residential"
>> [...]
>> 
> My state doesn't have such a limit, but my city does. Supposing I started 
> tagging things with source:maxspeed=US:VT:Burlington, would anyone be upset 
> that "Burlington" and "residential" are in the same place in the hierarchy?
> 
> (I'm hoping the answer here is no one cares, the value isn't intended to be 
> machine parsable, and both values are understandable by humans.)
> 

I think there are two reasons for the source:maxspeed tag:

1) So the next mapper who touches the maxspeed value knows where it came from.
2) To be able to find all the occurrences of maxspeed that were determined by 
the source. Something searchable but not necessarily machine parseable should 
be okay.

On Sep 8, 2014, at 10:30 PM, Marc Gemis wrote:
> 
> In Europe (at least Germany, Belgium, The Netherlands, UK) people started to 
> add both source:maxspeed=: and explicit 
> maxspeed tags. Then there is no need for an external DB to lookup the speeds. 
> Although it means that when the speed changes, all roads have to be retagged.

As long as the source:maxspeed value is unique to the jurisdiction then it is 
easy to find all the roads that need to be retagged.

On Sep 8, 2014, at 3:58 PM, Richard Welty wrote:

> the default speed limit in NYS for unposted roads is 55mph, irrespective of 
> surface type. other states vary; there's a page in the OSM wiki about it.
> 

If I recall correctly, NYS changed their rural highways from 50 MPH to 55 MPH 
when the nationwide 55 MPH limit came into effect in the early 1970s. So these 
speeds can definitely change, though usually change is slow.

I think that if the value for the source:maxspeed tag uniquely specifies the 
jurisdiction and is something that is readily understandable by a human then is 
should be okay. So US:CA:residential and US:VT:Burlington or 
US:VT:Burlington:residential would meet those requirements.

Sounds like the responders to this thread are either unopposed or generally in 
favor of the concept. I think I'll start tagging this way in my local area.

Thanks!
Tod


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Re: [Talk-us] Prima Facie Speed Limits

[Marc Gemis]

In Europe (at least Germany, Belgium, The Netherlands, UK) people started
to add both source:maxspeed=: and explicit
maxspeed tags. Then there is no need for an external DB to lookup the
speeds. Although it means that when the speed changes, all roads have to be
retagged.

regards


On Tue, Sep 9, 2014 at 1:00 AM, Tod Fitch  wrote:

> California has a 25 MPH rule for school zones while Arizona has (or at
> least had when I lived there) a 15 MPH school zone limit. It seems that 25
> MPH in a residential area is pretty standard but I think states have enough
> discretion in setting limits that they could vary from one state to the
> next. So I think the source attribution should allow for differences
> between states for the same class of road. Thus my suggestion for
> "source:maxspeed=US:CA:residential" for tagging in my area.
>
> On Sep 8, 2014, at 2:55 PM, Greg Morgan wrote:
>
>
>
> On Mon, Sep 8, 2014 at 2:27 PM, Tod Fitch  wrote:
>
>> Thus far I've only applied the maxspeed tag to roads with a posted speed
>> limit. But here in California most residential roads are not posted,
>> instead there is a state wide prima facie limit:
>> http://www.dmv.ca.gov/pubs/vctop/d11/vc22352.htm
>
>
> I wonder if 15 mph in a school zone and 25 mph in a residential area are
> some sort of federal standard?  The source tag might be useful but not much
> different than other states.
>
> Regards,
> Greg
>
>
>
>
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Re: [Talk-us] Prima Facie Speed Limits

[Andrew Guertin]

On 09/08/2014 05:27 PM, Tod Fitch wrote:

[...]
instead there is a state wide prima facie limit:
"source:maxspeed=US:CA:residential"
[...]


My state doesn't have such a limit, but my city does. Supposing I 
started tagging things with source:maxspeed=US:VT:Burlington, would 
anyone be upset that "Burlington" and "residential" are in the same 
place in the hierarchy?


(I'm hoping the answer here is no one cares, the value isn't intended to 
be machine parsable, and both values are understandable by humans.)


--Andrew

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Re: [Talk-us] Prima Facie Speed Limits

[Martin Koppenhoefer]

Am Montag, 8. September 2014 schrieb Tod Fitch :

>
> How does this sound?
>


+1

Cheers,
Martin


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Re: [Talk-us] Prima Facie Speed Limits

[Tod Fitch]

California has a 25 MPH rule for school zones while Arizona has (or at least 
had when I lived there) a 15 MPH school zone limit. It seems that 25 MPH in a 
residential area is pretty standard but I think states have enough discretion 
in setting limits that they could vary from one state to the next. So I think 
the source attribution should allow for differences between states for the same 
class of road. Thus my suggestion for "source:maxspeed=US:CA:residential" for 
tagging in my area.

On Sep 8, 2014, at 2:55 PM, Greg Morgan wrote:

> 
> 
> On Mon, Sep 8, 2014 at 2:27 PM, Tod Fitch  wrote:
> Thus far I've only applied the maxspeed tag to roads with a posted speed 
> limit. But here in California most residential roads are not posted, instead 
> there is a state wide prima facie limit: 
> http://www.dmv.ca.gov/pubs/vctop/d11/vc22352.htm
> 
> I wonder if 15 mph in a school zone and 25 mph in a residential area are some 
> sort of federal standard?  The source tag might be useful but not much 
> different than other states.
> 
> Regards,
> Greg
> 
> 

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Re: [Talk-us] Prima Facie Speed Limits

[Richard Welty]

On 9/8/14 5:55 PM, Greg Morgan wrote:
>
>
> On Mon, Sep 8, 2014 at 2:27 PM, Tod Fitch  > wrote:
>
> Thus far I've only applied the maxspeed tag to roads with a posted
> speed limit. But here in California most residential roads are not
> posted, instead there is a state wide prima facie limit:
> http://www.dmv.ca.gov/pubs/vctop/d11/vc22352.htm
>
>
> I wonder if 15 mph in a school zone and 25 mph in a residential area
> are some sort of federal standard?  The source tag might be useful but
> not much different than other states.
>
i doubt it. 30 mph residential is as common as 25 mph, and in my experience
it's a statute of the local municipality that imposes the limit.

the default speed limit in NYS for unposted roads is 55mph, irrespective
of surface type. other states vary; there's a page in the OSM wiki about it.

richard

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Re: [Talk-us] Prima Facie Speed Limits

[Greg Morgan]

On Mon, Sep 8, 2014 at 2:27 PM, Tod Fitch  wrote:

> Thus far I've only applied the maxspeed tag to roads with a posted speed
> limit. But here in California most residential roads are not posted,
> instead there is a state wide prima facie limit:
> http://www.dmv.ca.gov/pubs/vctop/d11/vc22352.htm


I wonder if 15 mph in a school zone and 25 mph in a residential area are
some sort of federal standard?  The source tag might be useful but not much
different than other states.

Regards,
Greg
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[Talk-us] Prima Facie Speed Limits

[Tod Fitch]

Thus far I've only applied the maxspeed tag to roads with a posted speed limit. 
But here in California most residential roads are not posted, instead there is 
a state wide prima facie limit: http://www.dmv.ca.gov/pubs/vctop/d11/vc22352.htm

I am considering tagging the unsigned speed limit on residential roads in my 
area and am thinking of tagging the authority of the speed with 
"source:maxspeed=US:CA:residential" based on an extension of the type of things 
I see at http://wiki.openstreetmap.org/wiki/Key:source:maxspeed

How does this sound? Objections? Is there a better way?

Thanks!
Tod


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