[Talk-us] [Talk-us-newyork] Highway classification guidelines for New York State

[Jmapb]

On 9/12/2021 2:50 PM, Kevin Kenny wrote:
> I should have been more explicit that this proposal is intended to
> dovetail with
> https://wiki.openstreetmap.org/wiki/United_States/Highway_classification
> <https://wiki.openstreetmap.org/wiki/United_States/Highway_classification>
> which attempts to set out more detailed, unified project goals. THe
> first sentence of the page references it, but it should be made more
> obvious that it's required background material.

I did read through the national classification page, though it looks
like it's been changed a few times since. It still lacks any clear
statement of goals, but that might be because it's positioned as a
documentation page not a proposal page.

 From what I gather, the overarching goals of the NY highway
classification revamp are simple enough: a logical application of
classification tags, more in keeping with their original use within the
UK, enabling better map rendering and routing. These probably hold true
on the national level too.

For NY, the detailed goals appear to be:

  - Connect all major population centers with a contiguous network of
motorway and trunk highways.
  - Eliminate spurs of motorway/trunk that do not terminate on a major
population center.
  - Eliminate islands of sub-trunk classification surrounded by trunks
(eg if a town is served by trunks from two or more directions, the roads
within the town that connect the trunks should be tagged trunk as well.)
  - Eliminate island segments of higher highway classification
surrounded by segments of lower classification (although possibly
segments of motorway surrounded by trunk could be allowed in some cases.)
  - Classify primarily by highways' roles in the network, not by
physical features or traffic regulations.
  - Prefer objective classifications derived from state DOT data over
subjective ones.
  - Attempt classification parity at Pennsylvania, New Jersey,
Connecticut, Massachusetts, Vermont, and Canada border crossings

I may have missed or misconstrued a few.


> I'd have to check on Flatbush Avenue Extension - the table was largely
> produced by a script, as you probably guessed.  It could be a link
> road mistagged as a motorway - there are a couple of those - or it
> could be the Marine Parkway Bridge.  (There are a couple of other data
> entry errors I've found in the NY data set; really, all
> 'authoritative' data need to be taken with a grain of salt.)

Flatbush Avenue Extension is just that, an extension connecting the
northern end of Flatbush Avenue and the Manhattan Bridge. I imagine they
probably would have just kept the name Flatbush Avenue except they were
out of street numbers (and thankfully chose not to use negatives.)

Though it is dual carriageway and features a slip lane onto Tillary
Street, it really has no motorway features. It has at-grade crossings
with stoplights and crosswalks. It's currently (correctly IMO) tagged as
primary.


> Definitely, NYC needs more discussion.  Here, I was trying to compare
> with UK tagging practice - which is the origin of the `highway=*`
> classification, and held up as an example that other nations should
> try to emulate.  Central London is relatively free of trunk, and even
> primary roads...

Is it? I guess I'm not sure what qualifies as "central" but I see plenty
of primaries even within the tightest loop of trunk "A roads". One thing
I don't see, though, is motorways -- they all terminate on the outermost
trunks. If we want NYC to look more like London, we'll have to pretend
the FDR and BQE aren't motorways.


> ... they tend to terminate at ring roads and not enter the city center
> as trunks/primaries, so perhaps the dearth of trunks in the Five
> Boroughs and Long Island makes sense.

I don't think it will make sense to the NYC locals (can't speak for Long
Island which is as foreign to me as Potsdam). I think mapping within NYC
has often followed the neighborhood-as-village paradigm, so the
primaries are the major routes between neighborhoods and boroughs.
(There's some historical justification for this -- Flatbush Avenue eg
once connected the village of Brooklyn to the village of Flatbush,
through the woods and swamps. Of course I'm sure London's chockablock
with historical justification too.)

But it would be good to survey some real opinions. I was cooking up
plans for some sort of mapper's delight last year but... anyway, I'll
see if anyone that I'm in touch with is interested.


> I'll say that I, at least, have no immediate plans to have a
> reclassification campaign for `primary` and below. From here on, the
> classification guidelines get much rougher.

I'm happy to hear that, first because the criteria appear to be a little
more debatable, and second because the workload would be enormous.

... Ok, I need to run out into the woods now, I'll finish reading this
message and check back into these threads when I return in a few days.

Ciao!

J


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