[Talk-us-massachusetts] Massachusetts Highway Classifications

Fri May 14 12:13:37 UTC 2021

"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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