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    <div class="moz-cite-prefix">On 24/05/18 13:47, Tod Fitch wrote:<br>
    </div>
    <blockquote type="cite"
      cite="mid:52588939-41FD-41F3-97D2-F68A382C7210@fitchdesign.com">
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        <blockquote type="cite" class="">
          <div class="">On May 23, 2018, at 7:57 PM, Paul Johnson <<a
              href="mailto:baloo@ursamundi.org" class=""
              moz-do-not-send="true">baloo@ursamundi.org</a>> wrote:</div>
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          <div class="">
            <div dir="ltr" class="">
              <div class="gmail_extra">
                <div class="gmail_quote">On Wed, May 23, 2018 at 10:34
                  AM, Tod Fitch <span dir="ltr" class=""><<a
                      href="mailto:tod@fitchdesign.com" target="_blank"
                      class="" moz-do-not-send="true">tod@fitchdesign.com</a>></span>
                  wrote:<br class="">
                  <blockquote class="gmail_quote" style="margin:0px 0px
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                    <div style="word-wrap:break-word" class=""><span
                        class="gmail-"><br class="">
                        <div class="">
                          <blockquote type="cite" class="">
                            <div class="">On May 22, 2018, at 12:48 PM,
                              Paul Johnson <<a
                                href="mailto:baloo@ursamundi.org"
                                target="_blank" class=""
                                moz-do-not-send="true">baloo@ursamundi.org</a>>
                              wrote:</div>
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                              <div dir="auto" class="">
                                <div dir="auto" class=""><br class="">
                                </div>
                                <div dir="auto" class="">In the case of
                                  your typical bog standard American
                                  residential street, I'm strongly
                                  disinclined to agree that this is a
                                  two lane situation.  I'd be inclined
                                  to mark unpainted lanes in the cases
                                  where channelization regularly occurs
                                  without the pavement markings anyway. 
                                  This isn't the case on residential
                                  streets, as people will tend to drive
                                  right up the middle of such streets,
                                  only movingly right to meet oncoming
                                  traffic and maybe when approaching a
                                  stop sign.</div>
                                <div class="gmail_quote" dir="auto">
                                  <blockquote class="gmail_quote"
                                    style="margin:0px 0px 0px
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                            </div>
                          </blockquote>
                        </div>
                        <br class="">
                      </span>
                      <div class="">Hmmm. I guess driving culture may
                        vary from place to place in the US. I always
                        keep to the right regardless of the existence of
                        a lane markings. I will admit, however, that
                        traffic studies indicate that the average driver
                        will be a bit more to the center of the pavement
                        if there are no lane markings. Similarly, at
                        least in residential areas, it has been found
                        that drivers will generally go slower if there
                        is no center marking. At least that is the
                        rational my local government is using to remove
                        the center divider marking for traffic calming
                        purposes.</div>
                    </div>
                  </blockquote>
                  <div class=""> </div>
                  <div class="">While this may be true, most people will
                    shy towards center (and perhaps even stay in center)
                    for most of their trip down a standard width street
                    (which, while typically 40 feet, this is <i
                      class="">inclusive</i> of all features including
                    sidewalks, making the effective width of the roadway
                    closer to 25 feet, a random pull from <a
                      href="http://www.mesaaz.gov/home/showdocument?id=1044"
                      class="" moz-do-not-send="true">Mesa, Arizona's
                      design guide</a> blindly from Google confirms
                    this, with their design guide being 27 feet across
                    between curbs), means that two full size pickups can
                    (barely) pass two cars parked on opposite sides of
                    the street at once.  That's also generously wide
                    compared to a lot of places, many suburban and small
                    town residential streets I've encountered are
                    open-edged with parking off the paved area, and the
                    paved area being maybe 20 feet on a particularly
                    wide street.  New urbanist street designs are
                    similarly, deliberately, narrow as a traffic calming
                    measure, as parked vehicles will tend to provide de
                    facto ad hoc chicanes.  As such, if lanes are marked
                    at all, it's usually at the very ends of blocks
                    only, where parking is prohibited, as a confirmation
                    that the street is indeed two-way and provide a hint
                    as to the default passing rule.</div>
                </div>
              </div>
            </div>
          </div>
        </blockquote>
        <div><br class="">
        </div>
        I have noticed that newer developments, especially infill
        development, have narrower residential roads than where I live.
        And I admit I did not look up current design standards. I simply
        took a tape measure to a number of residential streets in my
        neighborhood. The one in front of my house is 40’0" +/- 1"
        between the curbs. There are sidewalks but I excluded them from
        my 40’ number. Subjectively my current street seems about the
        same as others in the area and the same as my in previous
        neighborhood in a different city. Both neighborhoods are older,
        laid out when accommodating the automobile was high on the list
        of design criteria. It would be interesting to pull out the
        design standards that were in effect in the 1950s, 60s and 70s
        when much of our current suburbia was created. I would not be
        surprised if a lot of our current stock of residential roads are
        wider than the current standards specify.</div>
      <div><br class="">
      </div>
      <div>By the way, I don’t see a way to tag the accuracy or
        confidence level for a measurement. Seems like we ought to have
        something like *:confidence=*, similar to the *:lanes tagging so
        we could, for example tag the width of a road as:</div>
      <div><br class="">
      </div>
      <div>width=18’0"</div>
      <div>width:confidence=2’0"</div>
    </blockquote>
    The metrology term is 'uncertainty' .. so <br>
    <br>
    width:uncertainty=2'0" <br>
    To be complete there would need to be a statement of level of
    confidence and coverage factor. <br>
    However, for OSM simplicity, it could be assumed to have a normal
    distribution covering one standard deviation .. making the
    confidence level ~68% and the coverage factor ~1. <br>
    Of course the stated confidence level and coverage factor would be
    assessed by the next metrologist. <br>
    <br>
    There is a rough wikipedea thing on it .. it is rough.
    <a class="moz-txt-link-freetext" href="https://en.wikipedia.org/wiki/Measurement_uncertainty">https://en.wikipedia.org/wiki/Measurement_uncertainty</a> ... <br>
    Best to look at the second reference in that wikipedia page ... NPL
    do good articles. <br>
    <br>
    <br>
    <blockquote type="cite"
      cite="mid:52588939-41FD-41F3-97D2-F68A382C7210@fitchdesign.com">
      <div><br class="">
      </div>
      <div>If you are only estimating from the most likely source
        (allowable imagery) then you probably are not going to be much
        closer than 0.5 meters or a couple of feet.</div>
      <div><br class="">
      </div>
      <div>A confidence/accuracy tag would probably be another can of
        worms. How are you determining it? Statistically? One sigma? Two
        sigma? Or assume a single measurement but with a technique known
        to some typical error pattern?</div>
      <div><br class="">
      </div>
      <div>But I digress.</div>
      <div><br class="">
        <blockquote type="cite" class="">
          <div class="">
            <div dir="ltr" class="">
              <div class="gmail_extra">
                <div class="gmail_quote">
                  <div class=""><br class="">
                  </div>
                  <blockquote class="gmail_quote" style="margin:0px 0px
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                    rgb(204,204,204);padding-left:1ex">
                    <div style="word-wrap:break-word" class="">
                      <div class="">I know that road design varies over
                        the world and even, to a certain extent, within
                        different states in the United States. So this
                        discussion is showing different regional points
                        of view. A typical, or to borrow the UK slang
                         “bog standard”, American suburban residential
                        street is wide enough for parallel parking on
                        each side and space for trucks/lorries to get
                        past one another [1]. Typical parking lanes are
                        about 8 feet (2.4 meters) and a typical traffic
                        lane is 12 feet (3.7 meters). So a total
                        pavement width is typically around 40 feet (12.2
                        meters). In some parts of the world, even in
                        older crowded US cities, a road of that width
                        might be striped for four lanes of traffic. But
                        a typical US residential street has no lane
                        markings.</div>
                    </div>
                  </blockquote>
                  <div class=""><br class="">
                  </div>
                  <div class="">US tends to favor 9 feet per lane and 6
                    or 7 foot parking strips for a full size residential
                    street (and combine with 6 feet being the minimum, 7
                    becoming common, and even wider in some places for
                    the bike lane, this will feel quite clausterphobic
                    and many, if not most, drivers who will yield the
                    entire space to a vehicle passing a parked vehicle
                    first to stay out of the door zones).  Per federal
                    guidelines, a boulevard would be at least 10,
                    preferably 11 foot lanes (and this will still feel
                    quite narrow to most American drivers).</div>
                  <div class=""> </div>
                  <blockquote class="gmail_quote" style="margin:0px 0px
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                    <div style="word-wrap:break-word" class="">
                      <div class="">I can see the logic of only using
                        the lanes tag if there is paint on the pavement.
                        But that leads to another issue: It is pretty
                        easy from experience to glance at a photo of a
                        road and say it is wide enough for two lanes of
                        traffic. But it is much harder for me to
                        determine a width accurate to a couple of feet.
                        I don’t see a way to show a measurement error
                        estimate [2] and listing something as
                        width=40'0" implies much more accuracy than a
                        guess based on a quick visual survey or imagery
                        actually provides.</div>
                    </div>
                  </blockquote>
                  <div class=""><br class="">
                  </div>
                  <div class="">Look for the wear marks, these will be
                    quite prominent in sun-prone areas and where
                    concrete is used.  Generally speaking if there's
                    defined lanes that are just worn off, there will be
                    wear marks where passing motorists have rolled the
                    same spot repeatedly.  This can often be confirmed
                    with your favorite license-compatible street-level
                    imagery or a survey.  Though if you're using JOSM
                    and have suitably high resolution aerials available,
                    you can use JOSM to draw a line perpendicular to the
                    way from curbface to curbface to find the width.</div>
                </div>
              </div>
            </div>
          </div>
        </blockquote>
        <div><br class="">
        </div>
        My current favorite license compatible street level imagery is
        from my dash cam. :)</div>
      <div><br class="">
      </div>
      <div>I am considering getting another dash cam and rigging up
        something so that it faces out a passenger side window. I figure
        that would be a reasonable way to capture a bunch of shop
        details that I can’t get with a forward facing camera.</div>
      <div><br class="">
      </div>
      <div>Fortunately, or unfortunately depending on how you look at
        it, the lane markings in my area are kept in fairly good repair
        so seeing where they are worn off is often not possible.</div>
      <div><br class="">
        <blockquote type="cite" class="">
          <div class="">
            <div dir="ltr" class="">
              <div class="gmail_extra">
                <div class="gmail_quote">
                  <div class=""> </div>
                  <blockquote class="gmail_quote" style="margin:0px 0px
                    0px 0.8ex;border-left:1px solid
                    rgb(204,204,204);padding-left:1ex">
                    <div style="word-wrap:break-word" class="">
                      <div class="">I am rambling. To the point, if I
                        were to add my photo [1] to the urban highway
                        tagging examples page of the wiki [3] what tags
                        should it have. My current guess is:</div>
                      <div class=""><br class="">
                      </div>
                      <div class="">
                        <div class="">highway=residential</div>
                        <div class="">parking:lane:both=parallel</div>
                        <div class="">sidewalk=right</div>
                        <div class="">surface=asphalt</div>
                        <div class="">width=40'</div>
                      </div>
                    </div>
                  </blockquote>
                  <div class=""> </div>
                  <blockquote class="gmail_quote" style="margin:0px 0px
                    0px 0.8ex;border-left:1px solid
                    rgb(204,204,204);padding-left:1ex">
                    <div style="word-wrap:break-word" class="">
                      <div class="">
                        <div class="">For the specific example given by
                          the photo, what tags would you suggest.</div>
                      </div>
                    </div>
                  </blockquote>
                  <div class=""><br class="">
                  </div>
                  <div class="">
                    <div class="">Probably closer to 34'0" wide (we're
                      still in agreement on customary units that the
                      inches should be included even when not necessary
                      when tagging?), since those vehicles are narrower
                      than a full size pickup (typ. 7 feet) and up
                      against the curb, and so I'm reasonably sure
                      there's not more than 22 feet between them, but
                      more than 18 feet.  I'd still leave off the lanes.</div>
                  </div>
                </div>
              </div>
            </div>
            <br class="">
          </div>
        </blockquote>
      </div>
      <div class=""><br class="">
      </div>
      Only issue with fully specifying feet and inches is that it
      implies inch level accuracy with I doubt any of our road mapping
      achieves. See above for a digression on tagging
      accuracy/confidence levels.
      <div class=""><br class="">
        <div class="">I guess the question is: Would you leave off the
          lanes=* regardless of the width as long as there is no painted
          center line? If it is width dependent, at what width would you
          add a lanes=* tag even if there was no center line painted.</div>
        <div class=""><br class="">
        </div>
        <div class=""><br class="">
        </div>
      </div>
      <br>
      <fieldset class="mimeAttachmentHeader"></fieldset>
      <br>
      <pre wrap="">_______________________________________________
Tagging mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Tagging@openstreetmap.org">Tagging@openstreetmap.org</a>
<a class="moz-txt-link-freetext" href="https://lists.openstreetmap.org/listinfo/tagging">https://lists.openstreetmap.org/listinfo/tagging</a>
</pre>
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