Meh, in Australia we have plenty of these 2+1 roads with no fence, just road markers. We don't have an epidemic of head-on collisions. All you need to do is at the end of the '+1' section, have the outside lane merge into to inside lane. There's no 'sudden switchover' where traffic in the middle lane is coming at traffic going the other way.

Sometimes dysfunctional state politics plays a major role in US highway fatalities. E.g. I-5 [1] in Oregon. It has had numerous head-on crashes over the years because there are no barriers on large stretches of the road.

This isn't a "farm to market" road which some local hicks use to bring their vegetables in to the city to sell. This is the primary Interstate highway that goes North-South from the state of Washington thru the state of Oregon to the state of California. It's heavily used by both local commuters and long distance travelers.

BTW it rains a lot in Oregon!

[1] http://www.oregonlive.com/commuting/index.ssf/2014/11/odot_s...

As far I know, the wire fences primary purpose is to prevent cars from going into the opposite lane during a car crash.

Most roads just use a painted dashed line in the middle to indicate that you are on a 2+1, and a continuous white line if you are on the 1+2 side.