[talk-ph] changes of road types
riber101-osm at yahoo.com
riber101-osm at yahoo.com
Sat Jan 23 09:37:18 GMT 2010
Functional classification - not for newbies
For the arterial roads - down to classification of primary and secondary roads can be done to allow people to select major roads when traveling through an area.
These roads indicate a preferred traveling route. However in some places these roads will be narrow crowded streets through a barangay, however since they are the best option for getting through they are giving primary/secondary status.
The road CONDITION can be expressed by using surface, lanes and maxspeed information on sections with less speed routing can be done.
When a primary/secondary road is improved it maintains its classification, but the maxspeed or lanes may increase.
A major road will then be downgraded if another road is built that takes over its function.
When looking at pictures of many sections of the national highway the surface of the road, with and traveling speed indicates it should be a unclassified road, but its importance as an arterial road will increase its classification to guide people to use this road regardless of its state as it is the best alternative available.
So despite a guide based on pictures would indicate a road should be clearly unclassified it might be receive an "optional" upgrade to tertiary, secondary or primary based on its importance.
However since most of the primary and secondary road have already been mapped, this "optional" upgrade should never be considered by newbies, hehe.
So I suggest to keep things simple and base the classification solely on a picture guide for use by people with local knowledge.
I support the suggestion of the highway=road while tracking is done using satellite imagery.
Later people with local knowledge can adjust the classification based on a pictorial guide.
When looking for a classification of roads for the Philippines I stumbled over these maps from 2000.
I use a similar approach to Eugene.
Smallest roads = unclassified if industrial or with few houses, residential if the area is, well, residential...
Biggest roads and main links crossing the city = primary
The others secondary or tertiairy.
Trunc roads should be reserved for motorways with separated lanes without intersections/traffic lights in my opinion.
I use service roads inside parking lots or private terrains.
I mix this occasionnaly with a traffic based approach, downgrading primary roads or upgrading lower classes because of traffic importance.
If road classification is based on size and road condition only, countryside roads should be tracks only. But in Palawan I tagged the often unpaved road from PP to El Nido as primary (but with sections marked as unpaved)....
Printed maps also show this as main roads, and not as dirt tracks.
If road classification is based on traffic importance, N Escario street in Cebu should be primary (there is nearly as many traffic on this shortcut as on Reyes avenue)
Based on road size,one section of N Escario is a narrow unclassified road. Worse, it has a one way section, where the neighbouring residential roads handle all the traffic (jams) in the opposite direction.
I mapped it as secondary, since there were already some roads with that class. But now a unclassified road with heavy traffic, has the same importance on the map, as the often nearly empty 2x3 lanes around the Ayala mall.
I'll probably revisit the area, and downgrade it to tertiairy one of these days.
A good thing this is discussed, clear rules and examples are needed, specially for beginners.
--- On Fri, 1/22/10, Eugene Alvin Villar <seav80 at gmail.com> wrote:
> From: Eugene Alvin Villar <seav80 at gmail.com>
> Subject: Re: [talk-ph] changes of raod types
> To: "maning sambale" <emmanuel.sambale at gmail.com>
> Cc: "osm-ph" <talk-ph at openstreetmap.org>
> Date: Friday, January 22, 2010, 3:39 PM
> Here's my interpretation: unclassified
> and residential are the lowest-importance general roads.
> These two form the lowest level (above the service-type
> roads) and residential is used for roads within residential
> areas like subdivisions. Then in terms of increasing
> importance, roads go from tertiary, secondary, primary to
> trunk. trunk roads form the highest level of a road network.
> motorways are trunk roads that have special features
> (limited entrances, high-speed, often has toll fees, etc.).
> think of it like te circulatory system. trunk/motorway
> roads are the largest arteries and veins while
> unclassified/residential are the capillaries.
> hope this helps.
> On Mon, Aug 3, 2009 at 11:59 AM, Eugene Alvin Villar <seav80 at gmail.com>
> > I suggest that the tags for
> highway=trunk,primary,secondary,tertiary,unclassified be
> considered as a function of traffic patterns and not of DOTC
> designation nor physical appearance or condition.
> > These values should also be considered relative to
> local traffic patterns. This means that levels will be
> different in an urban and rural setting: a trunk in Metro
> Manila does not have to be equivalent in function to a trunk
> in Nueva Vizcaya.
> > Here are some descriptive interpretations I might
> suggest (subject to discussion):
> > trunk (rural) : long-distance route to traverse across
> > primary (rural) : mid-distance route to travel between
> towns in a province
> > secondary (rural) : major streets within rural towns
> > tertiary (rural) : major streets within areas of rural
> > unclassified,residential (rural) : other roads in
> rural towns
> > trunk (urban) : long-distance route across the
> > primary (urban) : major road within a metropolitan
> > secondary (urban) : mid-level road within a
> metropolitan city
> > tertiary (urban) : minor road in a metropolitan city
> > unclassified,residential (urban) : other roads in
> metropolitan cities
> > I'll admit that I have no fixed idea as to how to
> tag roads such that relative functional importance within
> Metro Manila (Cebu, Davao) is consistent when you get
> outside Metro Manila (Cebu, Davao).
> > The problem is that in urban areas, the road density
> is so high such that we need to differentiate the roads a
> lot, whereas in rural areas, the density is low.
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