We got into Oregon via US Route 101. That's really the only way up and down the coast line. To accommodate the slower traffic on hills, the road moves from a 2-lane two-way to a 3-lane two-way road, with the extra lane on the uphill side of the road. When the extra lane is going the oppisite direction, we have noticed a different highway sign about passing - "Yield Center Lane to Uphill Traffic". With a broken yellow line on your side this means you can pass if there aren't any vehicles in the second lane of oncoming traffic.
We haven't tried it nor have we seen anyone else do it. Sound/looks too scary for us.
