I enterred some coastline using PotLatch, and then had to reverse the order of it so that the sea wasn’t the land, etc (using JOSM).
Probably because the OSM server was being a bit cranky at the time, there are now 2 ways, and 2 sets of segments, in a couple of places in the data.
if you take a look here (Christchurch Estuary, New Zealand) http://www.openstreetmap.org/edit.html?lat=-43.53352955969494&lon=172.739884665532&zoom=12
and select the way that makes up the northern part of the estuary (when I try I get way# 4801684, but there are 2 so you might hit the other one), you can see what I mean.
If you open this location in JOSM instead (paste the above URL into the ‘bounding box’ dialog), and turn on ‘show direction of segments’, you will see that the ways around this estuary have all segments going in both directions - i.e. duplicated. How can I remove the wrong-direction way and segments, leaving the correct data in place? I find it almost impossible to select the bad way in JOSM, and when I did, and deleted it, all the bad segments were still there (just the ‘way’ was deleted), so I didn’t upload my changes. If I select in PotLatch I cannot tell if I have the good or bad way selected, and I haven’t figured how to delete complete ways there yet either.
Can anyone please help me sort out this mess? Don’t hack the data unless you know what you’re doing because I don’t want to have to digitise it all again! There are more duplicates further south from here too (Lyttleton Harbour) I think.