[Imports] "fleet manager" speed limit import proposal (Canada, USA)

Richard Weait richard at weait.com
Wed May 7 18:45:52 UTC 2014


Dear imports@

A followup on the fleet manager max speed data.

So far, I have explicit permission for using the data in OpenStreetMap
from the publisher.  I hold the test file, nobody has yet imported any
of the data.

Some new items.

On various lists / direct email, I've had technical suggestions that:

- We use an identifier for the submitter of the data.  So that we can
learn to trust one driver or another, more or less.
- We get a time stamp, or osmid version number with the way number, so
that we know that we are looking at a way that is unchanged since the
maxspeed report.

Both are fair enough as technical suggestions.

I would describe the community response as "cautious optimism".  So
far no suggestions that the data is unwanted or inappropriate.  Most
of the questions are around, "how can we best use this data?" and
"sure.  better speed limit data sounds good."

I've also looked at the data in more detail.

1) While I initially thought the data was limited to Canada / US, that
is not the case.  The data is worldwide, as the fleets involved are
international.  That's good and bad I suppose.  :-)  More communities
to get on board for us to proceed, I guess.  On the other hand a
country by country roll-out will probably help to limit negative
effects.  :-)

2) I expected the data to be entirely sensible and reflect the posted
speed limits.  I was surprised to find that some of the speed limits
are off-by-one of what I would expect.  Here is a summary of the km/h
data only, shown as number of reports followed by km/h value

      1 30
      1 35
      1 40
     24 50
     32 60
     18 70
    164 80
      4 90
     14 100
      2 121
      8 130

see that "121"?  That surprised me.  I don't know for sure that it
isn't on a sign somewhere, but still. :-)

We could campaign for more warnings for the submitters to only include
actual signed values.  These could also be typos.  We could drop data
like this as unreliable, do something else with it.

Next steps:

I'd like to look at the data in more detail.  The current format
(way_id and max_speed) isn't ideal for a slippy map overview, so I
added a few wayids to a slippy map with overpass.  Could you suggest a
nice way to do this so that I get 1400+ ways on a slippy map, without
hammering the edit api?

And from there, I'd like for some other mappers to take a look and
sanity check the data in their areas.  Perhaps by backing it up with a
ground survey.  Of course, I don't yet know where there are enough
items in an area to make it worthwhile.  So perhaps a visualization
first.

best regards and happy mapping,

Richard



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