On 20/10/2017 04:43, Nick Bolten wrote:
It will never be the case that the entire pedestrian network is added
all at once, or without disconnected portions.
I'd suggest that adding pedestrian routes without disconnected portions
is entirely possible. It needn't be the whole pedestrian infrastructure
for a city or county, but just adding a bit at a time, and ensuring that
each bit newly added it routable is entirely possible.
It's possible that during the process you'll find some disconnections
and won't have the data immediately to hand and need to go out and
survey, but SJ is relatively small, compact and walkable* so that really
shouldn't be a problem. An example of where data has been added and not
immediately connected is at
http://www.openstreetmap.org/#map=19/37.33469/-121.91613 - to me it
wouldn't make sense to add sidewalks without joins, because you'll want
to use routing as QA to make sure that everything links up properly, and
you can't do that if things "aren't supposed to link up yet".
Finding and fixing "unjoined way" routing issues after the event is far
more problematic than getting it right first time (I've had to do that
with lots of footpath data south of Manchester in the UK a few years ago
and figuring out "not routing because of access rights" and "not routing
because of a join error" is tricky)
On the router end, it should be as simple as either removing
disconnected subgraphs or preventing disconnected subgraphs from being
selected during the initial 'find the closest valid way' step.
It surely makes no sense to suggest that routers should change their
code to work around some incorrectly added data to OSM ...
Footways have pretty much one job - to support pedestrian routing (for
various values of "pedestrian", obviously). If they don't do that they
might as well not be there.
I'm in contact with the mappers putting in the time to map pedestrian
ways in San Jose and they're putting together a dataset of street
crossings to start importing. I'd like to suggest that we support
their endeavor and time commitments by supporting the inclusion of
street crossings, rather than discouraging mapping via threats of
reverts on changesets. Everyone's at the table and working to improve
the data.
Indeed, and there has been considerable supportive advice given (on this
list and elsewhere). Unfortunately what seems to be happening is that
this advice is sometimes being ignored. We should be aiming for a
"proper, complete map", in a case where a partial import actually makes
it harder to "map it properly" in the future then a revert of an import
makes complete sense - though the situation at
http://www.openstreetmap.org/#map=19/37.33498/-121.91646 suggests that
some post-import patching up (sometimes referred to as a "bucket and
shovel job") may be less work than "rework and start again".
Perhaps you could assure us that the mappers currently imported unjoined
ways will, with some urgency, make sure that they are actually connected
and that it won't be reliant on the wider OSM community to fix
everything up after the event?
Best Regards,
Andy
* even by European standards - as an occasional visitor to the northern
areas and the downtown for many years I found it more so than e.g. Portland.
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