[Tagging] Marking dual carriageways

[Jesse Crawford]

An example situation is visible here:
http://www.openstreetmap.org/#map=18/34.05688/-106.89005

Both California St and the nearby I-25 are two-way streets made up of two
parallel one-way streets. This has the advantage of thorough data, but it
introduces two issues that I see:

1) Information on crossover points is usually insufficient for surface
streets of this type, at least in the US. It is possible to make U-turns
and left turns from California St in many more places than the map shows,
but considering that these places are just small cuts in the divider it
seems excessive to make a small road object for each one.

2) When you zoom out, the two sides are still rendered separately but the
lines begin to overlap. It begins to look strange, e.g. two "California St"
labels on slightly different baselines will appear right next to eachother,
with one representing each side. A reference tying the two ways together
might provide map renderers information that they could use to prevent this
situation.


Jesse B. Crawford
Student, Information Technology
New Mexico Inst. of Mining & Tech

jcrawford at cs.nmt.edu | jesse at jbcrawford.us
http://cs.nmt.edu/~jcrawford | http://jbcrawford.us


On Thu, Jul 10, 2014 at 3:07 PM, Mateusz Konieczny <matkoniecz at gmail.com>
wrote:

> Road itself is not oneway as it has two one-way carriageways in opposite
> directions. Carriageways are mapped in OSM as separate one-way ways.
>
>
> 2014-07-10 21:32 GMT+02:00 John F. Eldredge <john at jfeldredge.com>:
>
> I am confused. You state that the road is divided into two carriageways,
>> that neither carriageway is one-way, and also that each carriageway is
>> one-way.  How can a given carriageway be both one-way and not one-way at
>> the same time?
>>
>>
>> On July 10, 2014 5:20:16 AM CDT, Mateusz Konieczny <matkoniecz at gmail.com>
>> wrote:
>> > I am thinking about marking tagging roads with separate carriageways.
>> > I
>> > want to create map with oneway roads, but in OSM data roads with
>> > separate
>> > carriageways that are not oneway are frequently represented as
>> > separate
>> > ways, both tagged as oneway.
>> >
>> > Adding tag that that would describe way as part of dual carriageway,
>> > with
>> > twin road leading in opposite direction would allow to solve this
>> > problem.
>> >
>> > I am currently thinking about good name for this tag and whatever
>> > there is
>> > possibly to achieve this result solely by processing OSM data
>> > (processing
>> > is probably necessary anyway to catch cases like
>> > https://www.openstreetmap.org/way/182138211 ).
>> >
>> >
>> > ------------------------------------------------------------------------
>> >
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>> --
>> John F. Eldredge -- john at jfeldredge.com
>> "Darkness cannot drive out darkness; only light can do that.  Hate cannot
>> drive out hate; only love can do that."
>> Dr. Martin Luther King, Jr.
>>
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>
>
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