[talk-au] Tagging for "unofficial" Cycle routes in Lake Macquarie?

[Ian Sergeant]

On Apr 27, 2012 12:43 AM, "Steve Bennett" <stevagewp at gmail.com> wrote:

> Verifiability and objectivity are the principles here - so let's call
> them that. "Map what's on the ground" fails in plenty of cases:
> - walking/bike routes (what's "on the ground" is a few signposts, nothing
more)
> - ferry routes (nothing)
> - many names, like business names, parks, mountains, etc
> - administrative boundaries
> - ski runs (minimal signage, and very hard to distinguish without
> supporting evidence)
> - abandoned railways
> - and, if we're being pedantic, tunnels, bridges, overhead cables, etc
etc.
>
> It's a marginally useful rule of thumb that quickly breaks down in any
> serious discussion. Don't overuse it.
>

On the contrary.  It is our touchstone whenever we encounter confusion or
ambiguity.  I'd argue it is useful in all the cases you have mentioned.  I
think you are interpreting "on the ground" too literally.  It means when
there is any controversy or ambiguity over what to map, we look to what is
physically present at a site right now to help us resolve it.  It means
what is physically present overrides an image, documentation, import, or
any other secondary document.  It means we rely on primary research of
actually going there and finding out what the situation is to be our final
arbiter.

Cycle and walking routes get relocated, torn up, fences put across them.
Ferry routes are where the ferry actually goes, not where the timetable
says it does (although on an open space, some degree of interpolation is
always required).  Park names?  The name that is on the park prevails -
quite often different to other sources.  Abandoned railways should have
evidence of having been there.  Tunnels, bridges, overhead cables can all
be verified by what is physically present, which overrides any other source.

On the ground doesn't mean we can't use other sources.  It just means that
when sources clash, we defer to what is on the ground.  This is in contrast
to Wikipedia, for instance, which will use a secondary source to determine
what to include.  OSM will always choose what is physically present, on the
ground.

> > Cycle routes are tricky, and we haven't got there yet.  Ask three
> > different road routing algorithms the for a best route, and expect
> > similar answers.  With cycle routes, that won't be the case, and many
> > different factors need to go into the weighting, and isolating the
> > routing factors and their weighting is developing.
>
> You're talking about something different. There's a difference between
> a pre-defined "cycle route", chosen by humans and backed up by some
> kind of signage, website, publication or whatever, and a dynamic,
> computed route between two places.
>

I know.  I'm simply saying that where no such human defined route backed up
by cycle facilities on the ground exists, we should include the features
present, not invent a route.

> To help people visualise a complete path from A to B to C to D, even
> if the "B to C" bit is indistinguishable from any other road "on the
> ground".
>
> For example, see this diversion from the Great Southern Rail Trail
> onto the South Gippsland Highway here:
> http://osm.org/go/uGumFQcy-?layers=C
>
> Let's say for the sake of argument that there is no bike lane, no
> signage, and the road is a busy one. It's still clearly correct to
> indicate the route along that road, because that's where the published
> route (
http://railtrails.org.au/index.php?option=com_railtrails&view=trail&id=144&Itemid=15
)
> goes.

No doubt it is in the map providers interest to make the route appear
connected, even when in reality they may not have made a single change to
the facilities on the ground.  However, the reality may be in some case
that there are actually gaps in the route.  I see this very much as an edge
case, and I can see arguments for including the connecting segments in an
official named route like this one.

However, in the case at hand, we're talking about separate cycle facilities
that are officially unconnected.  When navigating around cities, people may
be  joining for a section, and maybe utilising three or four different
routes in a trip, so finding a connecting path between cycle routes is a
common occurrence.

> Well, as we all know, everyone maps in different ways. I'd suggest
> that any and all of these things are potentially worth mapping:
> - physical infrastructure (bike lanes, bike paths, wide shoulders...)
> - signed routes
> - published official routes
> - published official planned routes
> - published unofficial routes (in moderation)
>
> It depends on the local circumstances, the likely audience, the
> inclinations of the mapper (and their time availability) and lots of
> other things.
>
> Steve
Adding physical infrastructure is always useful.  It never does any harm.
If accurate, it can either inform route choices, or be ignored.

Every bad route we add severely diminishes the value of the good ones, and
we see this happening already in Sydney.  There is a signed cycle route
heading down Parramatta Rd at Croydon.  This is a 3 lane, very narrow laned
road with heavy vehicles and high traffic volumes.  If we mark that in OSM
in a cycle route, we may as well give the game away.

I've no idea how you allow unofficial routes to be used in moderation.  How
do you decide which to keep?  How do you decide who gets to decide?  Would
OSM really be a better project if we were to do a data import from bikely?

Let's be careful with cycle routes in Australia.  The cycle facilities are
sparse compared to the bicycle signs and council routes.  There is no
central coordinating or certifying authority.  I'd argue against adding
personal routes, add the physical information for a router instead.  This
information is far more valuable, and as a project it plays to our
strengths.  I'd also argue against adding other routes where no cycle
facilities exist, or the route is dangerous.  Particularly where the
information is source from council maps that aren't recently updated, or
from bicycle signs that point off a main road or cycleway.

Ian.
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