5 ms·

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.

konspence 9y ago
Same in Vancouver, BC. The Lions Gate bridge has reversible lanes toggled by overhead signs. https://upload.wikimedia.org/wikipedia/commons/7/7e/Lions_Gate.jpg https://upload.wikimedia.org/wikipedia/commons/7/7e/Lions_Ga...
- Animats 9y ago
  The Golden Gate Bridge had that for decades, but there were too many accidents. A "zipper" barrier was considered many times, but early versions weren't strong enough to stay put if hit, or were too wide, eating up too much lane width. 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.jpg http://historicbridges.org/illinois/lincolnpark/ccp_passe.jp...
  - greeneggs 9y ago
    My memory is that the Golden Gate Bridge used movable traffic cones (pylons) for decades before the current barrier system. Was there a time that lane direction was only based on overhead signage?
    - Animats 9y ago
      Pictures of the bridge show a whole range of things the Golden Gate Bridge authority tried. Solid lines for every lane. Double lines down the middle. Neon signs ("2/3/4 lanes") at each end. Traffic cones at each end to guide cars into the 2/3/4 lane arrangement. Pylons that plugged into the bridge deck. (Probably post-1986, when the bridge deck was replaced, one section at a time. and the roadway was widened by two feet.) A "zipper" movable barrier was considered several times, but early versions were too wide or not strong enough. Finally they got one that worked.
janaagaard 9y ago
> 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.
- narrowtux 9y ago
  not really ;)
- wenc 9y ago
  > 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.
  - stirner 9y ago
    I saw the same thing in Ghana. On several occasions, the traffic light in the town’s busiest intersection would fail for hours, usually due to a “dum-sor” power supply shortage in the region[1]. However, all the drivers were very experienced with 4+-way intersections with no lights or signage, and everything progressed pretty smoothly (until I had to make my way through). [1] https://en.m.wikipedia.org/wiki/Dumsor https://en.m.wikipedia.org/wiki/Dumsor
  - matt4077 9y ago
    This sort of "chaotic-order" does indeed look impressive, and I've personally been mesmerised, just watching busy intersections in India or the Philippines. 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_deaths_per_VMT.png#/media/File:USA_annual_VMT_vs_deaths_per_VMT.png 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...).
lloeki 9y ago
IIRC near Paris there are some highways with an extra lane on the far side that is normally outright blocked by barriers that can hinge themselves away in case of heavy traffic. 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.
- toomuchtodo 9y ago
  Emergency lane.
RandallBrown 9y ago
That same thing also exists in the US. I've seen it in Ohio and New York.
- acjohnson55 9y ago
  Nicholasville Road in Lexington, Kentucky used this approach when I lived there. And I just saw the same thing in Silver Spring, Maryland yesterday. I'm guessing lights suffice on city streets, where lights are controlling traffic at intersections anyway.
wenc 9y ago
I've seen overhead lighted signboards that indicate direction of traffic at many U.S./Canada land borders. Typically the traffic at the border is asymmetric at different times of the day, so this really helps create efficient utilization patterns.
setr 9y ago
Chicago has a gated middle 2-lane express lane in the freeway. Gates go up on one side to allow traffic through, depending on traffic conditions, to force it one-way. What I've never been sure about is how they guarantee no one is still traveling in the wrong direction at transition time
- kgermino 9y ago
  Mostly cameras. However they do have someone actually drive the lanes (I believe it’s usually during the mid-day turn) at least once a day to make sure the road is completely clear (debris, etc.)
True-Saber 9y ago
In Germany a majority of people allowed to drive know how to really drive. I can only imagine the head-on pile up it would cause in the US. Half the time I'm just happy to get home alive, we may have some decent infrastructure but our driver training is near criminally bad.

konspence 9y ago

Same in Vancouver, BC. The Lions Gate bridge has reversible lanes toggled by overhead signs. https://upload.wikimedia.org/wikipedia/commons/7/7e/Lions_Gate.jpg https://upload.wikimedia.org/wikipedia/commons/7/7e/Lions_Ga...

Animats 9y ago
The Golden Gate Bridge had that for decades, but there were too many accidents. A "zipper" barrier was considered many times, but early versions weren't strong enough to stay put if hit, or were too wide, eating up too much lane width. 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.jpg http://historicbridges.org/illinois/lincolnpark/ccp_passe.jp...
- greeneggs 9y ago
  My memory is that the Golden Gate Bridge used movable traffic cones (pylons) for decades before the current barrier system. Was there a time that lane direction was only based on overhead signage?
  - Animats 9y ago
    Pictures of the bridge show a whole range of things the Golden Gate Bridge authority tried. Solid lines for every lane. Double lines down the middle. Neon signs ("2/3/4 lanes") at each end. Traffic cones at each end to guide cars into the 2/3/4 lane arrangement. Pylons that plugged into the bridge deck. (Probably post-1986, when the bridge deck was replaced, one section at a time. and the roadway was widened by two feet.) A "zipper" movable barrier was considered several times, but early versions were too wide or not strong enough. Finally they got one that worked.

janaagaard 9y ago

> 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.

narrowtux 9y ago
not really ;)
wenc 9y ago
> 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.
- stirner 9y ago
  I saw the same thing in Ghana. On several occasions, the traffic light in the town’s busiest intersection would fail for hours, usually due to a “dum-sor” power supply shortage in the region[1]. However, all the drivers were very experienced with 4+-way intersections with no lights or signage, and everything progressed pretty smoothly (until I had to make my way through). [1] https://en.m.wikipedia.org/wiki/Dumsor https://en.m.wikipedia.org/wiki/Dumsor
- matt4077 9y ago
  This sort of "chaotic-order" does indeed look impressive, and I've personally been mesmerised, just watching busy intersections in India or the Philippines. 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_deaths_per_VMT.png#/media/File:USA_annual_VMT_vs_deaths_per_VMT.png 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...).

lloeki 9y ago

IIRC near Paris there are some highways with an extra lane on the far side that is normally outright blocked by barriers that can hinge themselves away in case of heavy traffic. 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.

toomuchtodo 9y ago
Emergency lane.

RandallBrown 9y ago

That same thing also exists in the US. I've seen it in Ohio and New York.

acjohnson55 9y ago
Nicholasville Road in Lexington, Kentucky used this approach when I lived there. And I just saw the same thing in Silver Spring, Maryland yesterday. I'm guessing lights suffice on city streets, where lights are controlling traffic at intersections anyway.

wenc 9y ago

I've seen overhead lighted signboards that indicate direction of traffic at many U.S./Canada land borders. Typically the traffic at the border is asymmetric at different times of the day, so this really helps create efficient utilization patterns.

setr 9y ago

Chicago has a gated middle 2-lane express lane in the freeway. Gates go up on one side to allow traffic through, depending on traffic conditions, to force it one-way. What I've never been sure about is how they guarantee no one is still traveling in the wrong direction at transition time

kgermino 9y ago
Mostly cameras. However they do have someone actually drive the lanes (I believe it’s usually during the mid-day turn) at least once a day to make sure the road is completely clear (debris, etc.)

True-Saber 9y ago

In Germany a majority of people allowed to drive know how to really drive. I can only imagine the head-on pile up it would cause in the US. Half the time I'm just happy to get home alive, we may have some decent infrastructure but our driver training is near criminally bad.