IN Germany there is a similar thing. Instead of having a barrier, they have lights to indicate which paths who can use and change them according to traffic.
The article actually touches this:
> In theory, drivers could be directed to stay in particular lanes without dividers, but in practice: there is a long history of head-on collisions on the bridge.
I wouldn't be surprised if German drivers are more disciplined than the average. They sure are a lot better at keeping right on the freeway than us Danes.
In Rio de Janeiro, there are lanes that change directions at certain times of day (e.g. after 5pm), and the only thing that indicates this is a static signboard. When I first saw this I was horrified, but I'm told that people are able to easily adapt to the traffic flow and that it somehow works. Also, Brazilian drivers are used to driving in much more chaos than in most western countries, so this doesn't really faze them.
Ironically I've noticed that the least resilient drivers are usually those from developed countries when the traffic patterns and signage are regular and predictable.
But it's important to remember that despite all the skills these drivers exhibit every day, the number of traffic deaths under such circumstances is off the charts.
Meanwhile, those boring roads in western countries have gotten saver by a cool order of magnitude. See this chart: https://commons.wikimedia.org/wiki/File:USA_annual_VMT_vs_de...
It's actually quite a testament to the functioning of the American society over the last 50 years or so that they've been able to cut the number of traffic deaths by 90%, even though traffic has gotten a lot worse.
I quite like it as an example, because it didn't just require technological progress. It also included a political component (seatbelt laws, principles for save road construction etc), and cultural changes (drunk driving...).
Whenever you have a good system with average actors vs a bad system with some outstanding actors, the former usually wins in the long run. Good systems scale better and are more sustainable.
In the traffic case, the average skill of the drivers in Brazil is arguably higher than in America (they can maneuver into spots that Americans won't even try to, and drive at much shorter braking distances without getting into accidents), but the traffic fatality rate there is also a lot higher.
I've also noticed this in the corporate world. Big companies with good management but average employees tend to stick around for a long time (I won't name names, but a lot of people who work at big companies are decidedly mediocre).
Companies with bad management but better-than-average employees tend to get into a lot of trouble. (cf. Uber)
You want to have good systems and good actors, but when it is only possible to choose one, choosing the good system usually works well.
The graph shows deaths per billion miles. It looks like the number of deaths has remained constant even though traffic has gotten worse.
We have this here in Phoenix, Arizona; our north-south running "7th Street" has this kind of changeover for morning and evening rush-hour traffic to move people in/out of the downtown area quickly during weekdays (Monday-Friday). All other times it is meant to be treated as a median (suicide lane) for making lefts.
I haven't heard of many accidents on it in the 20+ years I've lived here; there have been a few, though. Usually the problems arise near the changeover times; some people's clocks are slow or fast, or they are paying attention, etc. So head-on collisions can occur, but they seem to be fairly rare. There's also the possibility of those not paying attention and rear-ending someone using the lane to make a left turn (I believe this is still legal, in order to access businesses along the route).
Personally, I try to avoid that lane - it just seems like the perfect setup for a one-way trip to the morgue.
I always wondered what the rationale was to _block_ the lane. Maybe it has to do with speed control (wider, empty roads induce a safety feeling) or an attempt to combat a form of Braess's paradox.
What I've never been sure about is how they guarantee no one is still traveling in the wrong direction at transition time
https://upload.wikimedia.org/wikipedia/commons/7/7e/Lions_Ga...
Lake Shore Drive in Chicago had solid lane dividers which were raised out of the pavement hydraulically.[1] These didn't work reliably and were abandoned in the 1970s.
[1] http://historicbridges.org/illinois/lincolnpark/ccp_passe.jp...
A "zipper" movable barrier was considered several times, but early versions were too wide or not strong enough. Finally they got one that worked.