Re: [Tagging] highway=primary/secondary/tertiary - tag according to quality or usage? (Paul Johnson)

[John Willis]

Javbw

On 7 Dec 2016, at 11:02 AM, Bradley White  wrote:

>> Unless being a surface expressway (trunk) or fully controlled freeway
>> (motorway), I tend to qualify anything that averages 7+ lanes as primary,
>> 5-6 lanes as secondary or primary, 4-5 lanes as secondary, 2-3 lanes as
>> tertiary, when otherwise not otherwise being a state (secondary) or federal
>> (primary) highway.
> 
> This is what the "lanes" tag is for. Trunk/primary/secondary/tertiary
> is not necessarily about quality or usage - it is fundamentally about
> road network importance. There are many extremely important roads in
> the U.S. that are only 2 lanes.

In Japan, it is the other end of the spectrum. The designations are purely 
legal designations. Many of the older, extremely narrow and winding "primary" 
roads have been bypassed (and officially signed as bypass roads) - but the 
smaller older roads still carry the "primary" designation while the larger (and 
in some cases, much less dangerous) bypass roads carry the tertiary designation 
because of legal definitions. 

A) the primary is a nationally recognized route, while the bypass was built by 
regional or local authorities, and the primary route is effectively replaced

B) both the primary and bypass routes are tagged as the same route and shield 
ref, and both follow routes that turn left and right at signals, meaning 
rendering color is the most important thing in Japan, in order to follow roads 
properly. 

I have set some of these "primary on paper only roads" to tertiary or 
unclassified in extreme situations where the road is almost impassible and 
dangerous - and totally unsigned as a way to deter people from using it, the 
bypass being the safer and signed route - but this is not a great way to handle 
it either. 

Trying to balance road classification, lanes, and legal designations is 
difficult when local customs and colors are not able to be managed in OSM/carto 
renderings.

Javbw. 
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Re: [Tagging] highway=primary/secondary/tertiary - tag according to quality or usage? (Paul Johnson)

[Bradley White]

> Unless being a surface expressway (trunk) or fully controlled freeway
> (motorway), I tend to qualify anything that averages 7+ lanes as primary,
> 5-6 lanes as secondary or primary, 4-5 lanes as secondary, 2-3 lanes as
> tertiary, when otherwise not otherwise being a state (secondary) or federal
> (primary) highway.

This is what the "lanes" tag is for. Trunk/primary/secondary/tertiary
is not necessarily about quality or usage - it is fundamentally about
road network importance. There are many extremely important roads in
the U.S. that are only 2 lanes. High lane counts, high speed limits,
or expressway-like features can be indicative of a a higher
classification, but it is not conclusive. There is a long article on
the wiki about road classification being fundamentally about network
importance and not road characteristics. One way I like to think about
it when deciding is to imagine if the segment of road in question
popped out of existence - how much of an impact would it have? Does it
simply mean a mile or two detour, or will it now take hours longer to
get from major city center to another major city center? How many
people would be cut-off from the rest of the world if the road
disappeared?

I agree for the most part with your point about road classifications
in the U.S. being stacked too high; especially, it seems the "primary"
tag is over-saturated. At least on the west coast of the U.S.,
however, I think there is an under-utilization of trunk classification
as well as unclassified. The former, because we still don't have an
agreed/uniform definition of "trunk" for the U.S.; the latter,
probably because it is not rendered distinctly anywhere but one zoom
level.

Tagging by road quality or characteristic leads to the weirdness that
is present at lower zoom levels, where trunk roads pop in and out of
existence in the middle of nowhere. This is worthless for
cross-country navigation, which is what motorways and trunks are
about. I could talk about this ad nauseum, but I'm getting off topic
now.

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Re: [Tagging] highway=primary/secondary/tertiary - tag according to quality or usage?

[Paul Johnson]

On Mon, Nov 28, 2016 at 7:36 AM, Greg Troxel  wrote:

>
> Michael Tsang  writes:
>
> > There are some highways which the quality isn't up to the usage,
> resulting in
> > congestion. Those highways connects high-quality motorway/trunk/primary
> > highways together for long distance traffic, but they only have a single
> lane
> > per direction, with lots of traffic lights, junctions, driveways, etc.,
> > resulting in slow traffic. Because the absence of roads of proper
> quality, those
> > low quality roads become bottlenecks in the whole network.
> >
> > A while ago, I tagged them all with highway=tertiary, consistent with the
> > quality of highways around the region, disregarding the actual kinds of
> traffic
> > on the highway, and someone retagged them as highway=primary reflecting
> the
> > actual usage for long-distance inter-town traffic, and send a message to
> me
> > about that.
>
> First, primary/secondary/tertiary is a UK notion.  In the US, we have
> more or less used that for US highway, state highway, and other
> important road between towns.
>

Which makes for some frustrating situations when someone decides to mass
retag entire counties to remove primary from undeniably massively major
(and often even moreso than motorways in the vicinity!) roadways to
secondary or less.

Unless being a surface expressway (trunk) or fully controlled freeway
(motorway), I tend to qualify anything that averages 7+ lanes as primary,
5-6 lanes as secondary or primary, 4-5 lanes as secondary, 2-3 lanes as
tertiary, when otherwise not otherwise being a state (secondary) or federal
(primary) highway.

Overall, I think if people really care about which tag is used, then
> other than arguing about formal road networks, that's a clue that
> routing or rendering is being done based on just the type, rather than
> the other attributes.
>
> If it is one lane in each direction, then tag the lanes value.  If there
> are stop signs ro lights, tag them.   Then, a router can make routes
> that correspond to the physical experience of driving.
>

I agree with this, and I tend to refine tagging to this end, within the
limits of what I think would be useful for vehicles I tend to have driven.
Exception being trains, where OSM is *entirely* irrelevant except for
simulation purposes, as railroads have their own train handling manuals (of
which I somehow don't have one for the Washington Park and Zoo Railroad
anymore, which I have driven for, but inexplicably and quite mysteriously
have a Burlington Northern one, which is vastly different) and as such,
traffic rules are more or less by necessity, proprietary, inconsistent, and
overridable by a railroad controller (which is why I keep undoing one-way
tagging on Portland's MAX lines that run in reserved lanes, for example,
since I am personally aware of the rules there and even on one-way streets,
they've strategically placed the trains in the left lane so they're
operating on the right side of the street when running in opposite the
usual direction by design, which happens on nearly a daily basis at the
start and end of service).


> Also, one lane in each direction is pretty normal for long-distance
> roads that really are primary, at least around me (US, outside of
> cities, not Interstates).Most highway=secondary are only one lane
> each way.
>

If it's a state highway, sure.  In absence of it being a state highway, I'd
probably tag that as a tertiary in most cases.  The US is somewhat
problematic in that there's been an upward crawl on tagging ways leaving
lower levels unnecessarily underutilized and higher levels a bit bunched.
Another overload in the US would be residential versus unclassified (the
difference I make there being whether or not people live on it or it just
being a street of nonresidential nature but not large enough to warrant
regular pavement markings).
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Re: [Tagging] highway=primary/secondary/tertiary - tag according to quality or usage?

[Martin Koppenhoefer]

2016-11-28 13:39 GMT+01:00 Michael Tsang :

> There are some highways which the quality isn't up to the usage, resulting
> in
> congestion. Those highways connects high-quality motorway/trunk/primary
> highways together for long distance traffic, but they only have a single
> lane
> per direction, with lots of traffic lights, junctions, driveways, etc.,
> resulting in slow traffic. Because the absence of roads of proper quality,
> those
> low quality roads become bottlenecks in the whole network.
>


it's more a problem of the highway network in that area than of the OSM
tagging though. Regularly congested roads with lots of traffic actually
indicate a high importance of that road, IMHO (while situations where this
is due to some event in the area are exceptions, e.g. roads around a
stadion where you only have congestion in case of a match or other event,
or after an accident, construction work, etc.).



>
> A while ago, I tagged them all with highway=tertiary, consistent with the
> quality of highways around the region, disregarding the actual kinds of
> traffic
> on the highway, and someone retagged them as highway=primary reflecting the
> actual usage for long-distance inter-town traffic,
>
>

road "quality" has several parameters and can already be tagged (lanes,
surface, maxspeed as an indirect indicator), highway is about the road grid
hierarchy. What you'd need for very good routing results (and ETA
calculations) is the actual current traffic speed on the individual
segments, something we can't tag in OSM anyway.

Cheers,
Martin
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Re: [Tagging] highway=primary/secondary/tertiary - tag according to quality or usage?

[Greg Troxel]

Michael Tsang  writes:

> There are some highways which the quality isn't up to the usage, resulting in 
> congestion. Those highways connects high-quality motorway/trunk/primary 
> highways together for long distance traffic, but they only have a single lane 
> per direction, with lots of traffic lights, junctions, driveways, etc., 
> resulting in slow traffic. Because the absence of roads of proper quality, 
> those 
> low quality roads become bottlenecks in the whole network.
>
> A while ago, I tagged them all with highway=tertiary, consistent with the 
> quality of highways around the region, disregarding the actual kinds of 
> traffic 
> on the highway, and someone retagged them as highway=primary reflecting the 
> actual usage for long-distance inter-town traffic, and send a message to me 
> about that.

First, primary/secondary/tertiary is a UK notion.  In the US, we have
more or less used that for US highway, state highway, and other
important road between towns.

Overall, I think if people really care about which tag is used, then
other than arguing about formal road networks, that's a clue that
routing or rendering is being done based on just the type, rather than
the other attributes.

If it is one lane in each direction, then tag the lanes value.  If there
are stop signs ro lights, tag them.   Then, a router can make routes
that correspond to the physical experience of driving.

Also, one lane in each direction is pretty normal for long-distance
roads that really are primary, at least around me (US, outside of
cities, not Interstates).Most highway=secondary are only one lane
each way.


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Re: [Tagging] highway=primary/secondary/tertiary - tag according to quality or usage?

[Philip Barnes]

On Mon Nov 28 12:39:44 2016 GMT, Michael Tsang wrote:
> Dear all,
> 
> There are some highways which the quality isn't up to the usage, resulting in 
> congestion. Those highways connects high-quality motorway/trunk/primary 
> highways together for long distance traffic, but they only have a single lane 
> per direction, with lots of traffic lights, junctions, driveways, etc., 
> resulting in slow traffic. Because the absence of roads of proper quality, 
> those 
> low quality roads become bottlenecks in the whole network.
> 
> A while ago, I tagged them all with highway=tertiary, consistent with the 
> quality of highways around the region, disregarding the actual kinds of 
> traffic 
> on the highway, and someone retagged them as highway=primary reflecting the 
> actual usage for long-distance inter-town traffic, and send a message to me 
> about that.
> 
> What's the correct tag then?
> 
It depends on the country, road classifications should be documented in the 
wiki for that country.

Phil (trigpoint)
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-- 
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