[Talk-us-massachusetts] Massachusetts Highway Classifications

Fri May 14 12:34:39 UTC 2021

Just a quick note that the prototype only has primary and above loaded in,
although there's a few secondary roads that got incidentally added via
editing when we pulled in certain routes.  The intent of the demo was
specifically focused on differentiating motorway/trunk/primary and to keep
the file sizes small for collaboration.

Your observations that primary and below deserve a stronger focus is well
noted.  So far we've focused on trunk simply because it seems to be the
most broken and needed an interstate definition.  Feedback/collaboration
welcome on how to craft definitions for the lower classes.  The wiki talk
page[1] and github issue tracker[2] are probably the best collaboration
spaces for folks that don't use Slack.

Wiki page with draft definitions:
[1] https://wiki.openstreetmap.org/wiki/United_States/Highway_classification

Github repo where we're hosting the data files and demo scripts:
[2] https://github.com/ZeLonewolf/us-highway-classification-demo

On Fri, May 14, 2021, 8:13 AM Greg Troxel <gdt at lexort.com> wrote:

>
> "Brian M. Sperlongano" <zelonewolf at gmail.com> writes:
>
> > I've been working with a group of mostly Northeast mappers (shout out to
> > aweech, Zeke Farwell, adamfranco, Rassilon, ZLima12, Kevin Kenny &
> > compdude) to develop new highway classification standards[3] that we're
> > hoping can evolve into replacement highway classification standards.  The
> > new guidelines that we've drafted emphasize road importance and through
> > connectivity, to ensure that map renders at lower zoom levels can
> > appropriately show long-distance road connectivity between population
> > centers.
>
> In general I think what you are proposing is a good thing.  I guess part
> of it is separating the three concepts physical, functional, and usage
> metrics, and part of it are two arguments about which of those
> primary/secondary/ and so on should be controlled by, and then how
> rendering decisions (both color and whether to show are made.  Given the
> problem of how the default render has more influence than it should, I
> can see the point that making the adjustment by
> primary/secondary/etc. classification is the only viable path.
>
> > [3]
> https://wiki.openstreetmap.org/wiki/United_States/Highway_classification
>
> I do think that what I view as the previous consensus that trunk be
> physically "almost motorway but not quite" is an important concept, and
> certainly should be tagged and arguably renders should show it.  But I
> don't think it's necessary that it control highway=trunk.   I see the
> proposal basically says that near cities, if it isn't the old defintion
> physically, it shouldn't be trunk, but trunk can be used for physically
> lesser roads that are still a big deal.  US 20 in Wyoming might be a
> good example.   So I like that part of the proposal.
>
> What's missing is how to use secondary and tertiary.
>
> We used to have a notion that in MA, all state routes were at least
> secondary.   I think that continues to make sense in most cases but I
> don't know how that lines up with the labeling below.
>
> > While developing these guidelines, we discovered that the MassGIS
> > "functional classifications" mapped quite nicely to functional highway
> > classifications, however, the "trunk" classification was under-used
> > compared to its place in the hierarchy.  This is likely the result of a
> > 9-year old MassGIS road classification mapping which did not map anything
> > to trunk.  On review of the current mappings, we believe that the
> following
> > mappings make sense:
> >
> > F_Class 2 -> highway=trunk
> > F_Class 3 -> highway=primary
> > F_Class 5 -> highway=secondary
>
> and what about tertiary/unclassified?
>
> > In many cases, the mappings above are already implemented in the map, and
> > some would need to be changed.  There are a small number of outliers to
> > this mapping that we may want to consider documenting as exceptions, such
> > as local routes through Fitchburg and in the Plymouth area that are
> > probably more appropriately mapped lower than trunk.
>
> I wonder how much of that is a bug in the MassGIS data.   (I think
> really this is MassDOT data made available via MassGIS.)
>
> > In order to "try before you buy", we've stood up a temporary prototype
> > render[4] to demonstrate what the regional road network would look like
> if
> > we adopted these changes in highway classification.  This stripped-down
> > render shows only roads, boundaries, and city names, and is rigged to
> > suppress rendering of primary and below until higher zooms, so you can
> > better see the motorway/trunk road network.
>
> When  I look at this, I see
>
> > The prototype render has implemented highway reclassifications for four
> New
> > England states only: NH, VT, MA, and RI.  In addition, Washington State
> has
> > also been reclassified in this prototype.  Note that these changes are
> ONLY
> > in this prototype and not in the live map at osm.org, and you can
> compare
> > the two maps side by side to see the difference.
> >
> > [4] http://74.97.52.189:6789/openstreetmap-carto/#8/41.965/-71.084
>
> I went to look near me, and the zoom 8/9 look good.  The road from
> Gardner to Keene NH being trunk is interesting as I don't think of that,
> but I can easily believe that it's a big deal at the 50 km scale, an
> indeed I have personally used it to drive to mid Vermont.  So that seems
> positive.
>
> At zoom 10 I see primary pop in, and much of that is ok but it seems
> kind of strange.   Near Marlboro, the bit about the Rt 85 connector and
> 85 up to 62 and west beyond 495 qualifying but not 62 to Bedford doesn't
> make sense.
>
> Going to zoom 11, I don't see 117 and 62 appear, and they should.
> Certainly these should be secondary; they are very important when
> driving to 5 towns away, but not important when driving from Boston to
> Worcester.
>
> I think either the illustration doesn't show what I want to see, or I am
> misunderstanding it.  I wonder if it's possible to show all roads with
> proposed changes, with the scale-dependent visibilty that the default
> scale now has?
>
> Or perhaps this is only meant to show what counts as primary, and the
> rest is to be figured out?  If so, I don't mean to complain about it.
>
> My big comment is that the proposal doesn't address
> tertiary/unclassified.  Two separate thoughts:
>
>   1) I've long thought that there should be an idea, which really is
>   aligned well with what you are proposing, that e.g. tertiary should
>   mean something like "tertiary is a road thought of as 'the way from
>   here to there' relative to two places (defined broadly) that have
>   about 10000 people each".  Or maybe some smaller number, or maybe that
>   number floats with density.  Basically in MA, roads that are the main
>   paths between towns, at the Central Mass town scale.
>
>   2) In the UK, they have this "Unclassified" notion.  That never made
>   sense to me until I drove there.  Their A/B/C are really functional
>   classifications; some A roads are like small US Highways (everything's
>   narrow but I'll ignore that).  By the time you get to C, they are very
>   minor.  I really remember only one U road, and it went from a very
>   small town through a tiny village (cows in the road almost) back to
>   the main road.  The main road into to the village was a C.  The U road
>   was one lane and you'd have to back up to a passing place if you met
>   another car -- but we didn't.  Still, it had a number.  (I can't find
>   this now).
>
>   Here, we sort of have "if it doesn't merit tertiary or higher, call it
>   residential if it has houses, and unclassified if not", and that
>   doesn't really make sense.  The UK "unclassified" is really a formal
>   designation and probably should have been "quartiary".  In the US,
>   whether roads have houses is kind of random and not all that
>   correlated.
>
>   So I tend to want to get rid of highway=residential, replace it with
>   highway=local (meaning any legal road that you don't use to get from
>   here to there, only to get to a particular place that is part of
>   here), and use highway=unclassified from "how to get from one part to
>   10kish-town to another part, or perhaps "how to get from a 1k place to
>   a different 1k place".  Once arriving that that, given avoiding churn,
>   I want to just drop the "houses" part of residential, and say that
>   highway=residential means what I said about above highway=local.
>
> > Would the Massachusetts mapping community support adopting this MassGIS
> > functional class mapping, either with or without documented exceptions?
> > For anyone that wants to get involved with this effort more deeply,
> > collaboration is welcome, and we continue to discuss and work out the
> kinks
> > on Slack, in channel #local-us-northeast .
>
> I think this is heading to something I could support pretty strongly.
> Hopefully my comments made sense.
>
> (It's unfortuante that this is on Slack; I don't think open data
> projects should use proprietary platforms.)
>
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