4 ms·

Interestingly enough, while it looks bizarre in a video game, this is functionally how left/right turn bays work in some large urban one-way streets in real-lif

by rmxt 12y ago

Interestingly enough, while it looks bizarre in a video game, this is functionally how left/right turn bays work in some large urban one-way streets in real-life. See, for example, this NYC intersection: https://goo.gl/maps/SCFrQ https://goo.gl/maps/SCFrQ . The left turn lane is a parking lane until one is within half a block of the intersection in question. While it isn't as extreme as 2 lanes to 6, it's very similar. So... is it a hack for the game, or is it a hack for real-life, or neither?

redler 12y ago
I walk through that intersection most days. What they've done in NYC is interesting. That part of First Avenue used to be, like most in mid and upper Manhattan, six (or sometimes more) undifferentiated lanes. The first change was the addition of dedicated bus lanes (right-most lane, painted reddish), complete with violation cameras and automated ticketing. This reduced competition among buses and cars -- in favor of buses, leading to somewhat better bus throughput. Cars now had five lanes -- although with parking in at least the left-most lane, and delivery trucks double-parked adjacent to the cars, more like three. Then came the big bike lane initiative. In the book Traffic, by Tom Vanderbilt, some of the takeaways are that parked cars can form a buffer between flowing traffic and bike lanes, and that narrowing roads at intersections through the addition of islands with trees on them increases pedestrian safety (in no small part by reducing the speed of turning cars at intersections). To varying degrees they've applied these ideas -- the left-most lane is now entirely a bike lane (painted green, complete with its own traffic signals). Next to that is a dedicated parking lane -- yes, in lane two -- often buffered by concrete islands at intersections, with a tree or two. You can see this here [1] Cars now have three or perhaps four lanes for general travel. For left turns, the bike and parking lanes are cut by a dedicated left-turn waiting lane [2] (usually with its own left turn signal, so left turners are not fighting pedestrians in the crosswalk). On some avenues they then added "Select Buses", which work on a "trust-but-verify" honor system so riders can enter and exit quickly through any of three wide doors without queueing to dip a Metrocard. Finally, they cut the city-wide speed limit to 25 miles per hour, adjusting the timing of avenue traffic signals accordingly. The result of all this has been much gnashing of teeth and rending of garments, but as a whole it's made the city substantially better for bikers and pedestrians, and in many cases left turns are much easier for drivers. [1] https://www.google.com/maps/@40.771088,-73.9538,3a,75y,53.97h,67.76t/data=!3m4!1e1!3m2!1svoxzueWCAGhdwHjSDRETtQ!2e0 https://www.google.com/maps/@40.771088,-73.9538,3a,75y,53.97... [2] https://www.google.com/maps/@40.771088,-73.9538,3a,65.7y,194.74h,66.74t/data=!3m4!1e1!3m2!1svoxzueWCAGhdwHjSDRETtQ!2e0 https://www.google.com/maps/@40.771088,-73.9538,3a,65.7y,194... [Edit: clarity]
- tricolon 12y ago
  I've been casually following the same issues for a few years and this is a good summary.
mikeash 12y ago
Stuff like that is pretty common in suburban Northern Virginia (for example). There are lots of busy roads with two lanes in each direction which expand to three, four, five, or even six lanes at intersections with dedicated turn lanes. I think the only reason that "proposed hack" screenshot looks so weird is because the distance between intersections is much, much shorter than it would be in real life, relative to the width of the road. For example, you can see it in action in various amounts for all four directions of this intersection: https://www.google.com/maps/@38.9770719,-77.3149885,438m/data=!3m1!1e3 https://www.google.com/maps/@38.9770719,-77.3149885,438m/dat... But it doesn't look comical, because the roads are proportionately much more slender and the transitions more gradual. I haven't played the game, but it sounds like it ended up being accurate here!
- nmeofthestate 12y ago
  It sounds like the game is inaccurate in how it models traffic, because in real life people do move out to make use of empty inner lanes (outer lanes? I can never remember). NB: I've not played the game so I'm not 100% on what the traffic problem is, exactly.
  - UberMouse 12y ago
    The problem stems from the car AI being crazy aggressive in it's lane switching. They will switch to the lane for their exit the instant they can, even if they still have to travel around the entire city to get to it. Leading to middle lanes not getting as much use (At least without careful planning to ensure there is something they can exit the road from the middle lanes with) and potentially large backups of a single line of cars waiting to turn right (Even when the lane right next to it is also a right turn lane). They also cannot merge properly so I end up placing exits on both side of my highways (For both incoming and outgoing traffic) with one side coming up and over the road to join into the other sides exit to limit congestion. Not that any of these things are completely unrealistic but it is occasionally annoying when your traffic is backed up solely because they're ignoring the adjacent lane.

by rmxt 12y ago

redler 12y ago

I walk through that intersection most days. What they've done in NYC is interesting. That part of First Avenue used to be, like most in mid and upper Manhattan, six (or sometimes more) undifferentiated lanes. The first change was the addition of dedicated bus lanes (right-most lane, painted reddish), complete with violation cameras and automated ticketing. This reduced competition among buses and cars -- in favor of buses, leading to somewhat better bus throughput. Cars now had five lanes -- although with parking in at least the left-most lane, and delivery trucks double-parked adjacent to the cars, more like three. Then came the big bike lane initiative. In the book Traffic, by Tom Vanderbilt, some of the takeaways are that parked cars can form a buffer between flowing traffic and bike lanes, and that narrowing roads at intersections through the addition of islands with trees on them increases pedestrian safety (in no small part by reducing the speed of turning cars at intersections). To varying degrees they've applied these ideas -- the left-most lane is now entirely a bike lane (painted green, complete with its own traffic signals). Next to that is a dedicated parking lane -- yes, in lane two -- often buffered by concrete islands at intersections, with a tree or two. You can see this here [1] Cars now have three or perhaps four lanes for general travel. For left turns, the bike and parking lanes are cut by a dedicated left-turn waiting lane [2] (usually with its own left turn signal, so left turners are not fighting pedestrians in the crosswalk). On some avenues they then added "Select Buses", which work on a "trust-but-verify" honor system so riders can enter and exit quickly through any of three wide doors without queueing to dip a Metrocard. Finally, they cut the city-wide speed limit to 25 miles per hour, adjusting the timing of avenue traffic signals accordingly. The result of all this has been much gnashing of teeth and rending of garments, but as a whole it's made the city substantially better for bikers and pedestrians, and in many cases left turns are much easier for drivers. [1] https://www.google.com/maps/@40.771088,-73.9538,3a,75y,53.97h,67.76t/data=!3m4!1e1!3m2!1svoxzueWCAGhdwHjSDRETtQ!2e0 https://www.google.com/maps/@40.771088,-73.9538,3a,75y,53.97... [2] https://www.google.com/maps/@40.771088,-73.9538,3a,65.7y,194.74h,66.74t/data=!3m4!1e1!3m2!1svoxzueWCAGhdwHjSDRETtQ!2e0 https://www.google.com/maps/@40.771088,-73.9538,3a,65.7y,194... [Edit: clarity]

tricolon 12y ago
I've been casually following the same issues for a few years and this is a good summary.

mikeash 12y ago

Stuff like that is pretty common in suburban Northern Virginia (for example). There are lots of busy roads with two lanes in each direction which expand to three, four, five, or even six lanes at intersections with dedicated turn lanes. I think the only reason that "proposed hack" screenshot looks so weird is because the distance between intersections is much, much shorter than it would be in real life, relative to the width of the road. For example, you can see it in action in various amounts for all four directions of this intersection: https://www.google.com/maps/@38.9770719,-77.3149885,438m/data=!3m1!1e3 https://www.google.com/maps/@38.9770719,-77.3149885,438m/dat... But it doesn't look comical, because the roads are proportionately much more slender and the transitions more gradual. I haven't played the game, but it sounds like it ended up being accurate here!

nmeofthestate 12y ago
It sounds like the game is inaccurate in how it models traffic, because in real life people do move out to make use of empty inner lanes (outer lanes? I can never remember). NB: I've not played the game so I'm not 100% on what the traffic problem is, exactly.
- UberMouse 12y ago
  The problem stems from the car AI being crazy aggressive in it's lane switching. They will switch to the lane for their exit the instant they can, even if they still have to travel around the entire city to get to it. Leading to middle lanes not getting as much use (At least without careful planning to ensure there is something they can exit the road from the middle lanes with) and potentially large backups of a single line of cars waiting to turn right (Even when the lane right next to it is also a right turn lane). They also cannot merge properly so I end up placing exits on both side of my highways (For both incoming and outgoing traffic) with one side coming up and over the road to join into the other sides exit to limit congestion. Not that any of these things are completely unrealistic but it is occasionally annoying when your traffic is backed up solely because they're ignoring the adjacent lane.