Re: FW: UK Motorways 100% Complete

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Re: FW: UK Motorways 100% Complete

Etienne Cherdlu
Yes, this is only the first cut of the motorways.  As more points are
uploaded there is plenty of scope for revisiting and refining the
existing segments.  I see this as the start of the process not the

Indeed I've been thinking quite a lot about how, in general, paths can
be reviewed and verified, and how this can be translated into a
statement of confidence/accuracy.

As with Wikipedia the strongest argument against not using OSM is to
doubt it's accuracy, quality and completeness.  Of course *we* know
the maps will be good enough but we could expect Multimap or whoever
to play this card if they ever felt threatened.

Some thoughts:

Accuracy.  Maybe labels could be used to tag each road with a
subjective grading of accuracy.  The presence of good GPS tracks can
help to assess this.  Perhaps a simple scheme like:  Low - no GPS
data, Medium - some GPS data, High - copious GPS data.

Quality.  I've noticed roads that don't have enough nodes on bends and
curves.  These can deviate significantly from the best fit path.
There are also other qualitative factors, such as the omission of
mini-roundabouts (which may not show up from GPS tracks at all),
flares on roundabouts, intersection topology, etc.

Completeness.  The UK Motorways project originated from my original
though "How do we know when we are done?".  To measure completeness we
need a database of all motorways, major roads and minor roads and for
every city, town and village we need a complete catalog of streets.  I
think that only then can we start to be able to say that a place is or
is not complete.


> -----Original Message-----
> From: Andy Robinson [mailto:[hidden email]]
> Sent: 07 January 2006 17:27
> To: [hidden email]
> Subject: RE: [Openstreetmap] UK Motorways 100% Complete
> Pat on the back to all those who have worked on the UK to date.
> Just to point out that although all the motorways in the UK are "completed"
> they are by no way complete and we still need people to have their gps
> logging running when travelling on them or over them. Many of the recent
> motorway edits use a mixture of the Landsat background and sparse GPS data,
> often on only one carriageway, so we still need to lay down more points to
> provide better map accuracy.
> The other point is the junctions. We have a large number still to map. Which
> brings me to another suggestion:
> Although it might look odd to other road users, may I suggest that whenever
> anyone logs dual carriageway and other major road junctions at motorways
> (equally applicable elsewhere), drive around each roundabout/rotary at least
> one full revolution (more if logging interval is less frequent) so that we
> can see a good trace. It then makes it much easier to place the road
> slips/exits, even if they haven't been travelled.
> Cheers,
> Andy Robinson
> (Blackadder)
> >-----Original Message-----
> >From: [hidden email] [mailto:openstreetmap-
> >[hidden email]] On Behalf Of Etienne Cherdlu
> >Sent: 07 January 2006 10:45
> >To: [hidden email]
> >Subject: [Openstreetmap] UK Motorways 100% Complete
> >
> >Folks
> >I'm pleased to announce that the main carriageways of all mainland UK
> >motorways have been completed.  Over 3,000 km of roadway.
> >
> >This does not include motorways in Northern Ireland nor does it include
> >motorway sections of A roads, so there is still plenty of work to do.
> >
> >Etienne
> >
> >_______________________________________________
> >Openstreetmap mailing list
> >[hidden email]
> >
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