Personally I think it depends on whether the construction is for repairs/maintenance and the road will eventually revert back to its original layout, or if its building/realigning the highway and the eventual result will be different. For the first case, the map should be left alone. In the second case, there is no harm in gradually updating the map with the developments so that when the work is finished, the map is already ready with the new layout.

I’m not a fan of the line from the border to the centre - if a sprinkler covers a full circle, just map it as a circle.

I tagged this way as causeway=yes, tidal=yes. At the time, I couldn’t find any established system for tagging these types of roads.

I would love to help, but as I’m not from the US I think I would probably do more harm than good. I’ve noticed there is a small Seattle usergroup (osm.wiki/Seattle,_Washington) - have you tried organising a group remapping effort with them?

I’ve taken a look at the ‘badmap’ for Seattle - it seems like one person should be able to at least remap the affected interstates and other main roads in probably a couple of hours. I would suggest focussing on the major pieces of infrastructure first; while it’s a shame to lose things like parks and buildings I imagine they will quickly get mapped again :)

The absolute best way to start is to see if you can avoid remapping in the first place, by working out who the main contributors in your area are that haven’t accepted, and trying to contact them. Have a look at osm.wiki/Asking_users_to_accept_the_ODbL

Good stuff! I'll be moving to the area in a few months, so hopefully I'll be getting lots of mapping done around the area too.

I would disagree with automagically rejecting reports - while a single report like that is mostly useless, a few of them in the same area is a strong hint to a local mapper that 'something is wrong', and that the area would be worth resurveying/checking.