Hi,
Today I experimented with using OSM maps on my Garmin sat-nav. The one thing
that I noticed was that roundabouts do not work well. The problem seems to be
the slip roads entering the roundabout. The sat-nav recognises them as a
roundabout in themself, and because of that gives some fairly poor directions,
for example:
• Drive 10 miles then enter roundabout.
(Drive 10 miles)
• Enter roundabout.
(Enter the slip road to the roundabout)
• Enter roundabout and take the third exit.
As you can see, because of the slip road's existence the GPS does not announce
which exit you're expecting to take until the last minute. This means that you
can't get in the right lane early enough.
Proposed solutions (all of which are horrible):
1) Don't tag sliproads onto roundabouts as junction=roundabout, instead use
some other tagging scheme. Not greatly desirable because it involves a *whole*
lot of retagging.
2) Ask garmin to fix it (doesn't sound likely).
3) Write some fancy heuristics in the conversion from OSM to routable garmin
maps that figure out when you're looking at slip roads and when it's an actual
roundabout (sounds unreliable).
Can anyone thing of a better solution to this?
Bob
if (*ra4 != 0xffc78948) { return false; }
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