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I am astonished that green light engineering has not gotten more attention/application over the last, say, 20 years. So much data is available and 99 percent o

I am astonished that green light engineering has not gotten more attention/application over the last, say, 20 years. So much data is available and 99 percent of all traffic lights seem to be following simple timer logic at worst and some vehicle detection at best, to prevent giving green to non existing traffic. It almost feels like a no-brainer to start optimizing light signaling by leveraging the massive amounts of data and simulation techniques we have since not far into this century. That said, I'm not sure / concerned about, how well protected our (location) data is when sharing vast amounts of it between governments and huge for-profit companies.

callalex 3y ago
Almost all infrastructure spending is a no-brainer that puts more into the economy than it takes out, but the USA is completely allergic to it anyways. This part of infrastructure is not unique in that regard.
- jacobr1 3y ago
  The US spends very high amounts of money on infrastructure ... but like in many other areas gets a very poor return on that investment. We underinvest relative the both the current need and potential benefits, but it isn't because there isn't a willingness to spend.
  - ethanbond 3y ago
    It’s a great investment for the landlords nearby! https://en.wikipedia.org/wiki/Henry_George_theorem?wprov=sfti1 https://en.wikipedia.org/wiki/Henry_George_theorem?wprov=sft...
  - outside1234 3y ago
    and it gets a very poor return on investment because it is done inefficiently - think of the 60 foot wide roads and everything else you have seen.
  - zmgsabst 3y ago
    The US spends high amounts on everything from infrastructure to healthcare to education to anti-poverty. The gaslighting that we don’t spend enough comes from the corrupt groups looting the public to deliver stupendously bad results. Most people opposed to government spending oppose that corruption and theft, not the underlying project. Eg, rail projects that are ridiculously expensive by international standards.
    - jacobr1 3y ago
      Yep, in my local area, light rail gets proposed all the time. And I'm not against it in principle. But the specific project proposals, even with their optimistic ridership numbers, pan out to something like we could buy every rider their own mid-sized sedan and pay for a personal driver for the same overall sticker-price. Figuring out the cost-effective way to deliver those kinds of project, improving state capacity, seems supremely important for the US.
6stringmerc 3y ago
I worked in a field where signals were a big component. Nationwide - the variety is quite real. It could be skilled labor. Some are mechanical switches still.
akira2501 3y ago
Light timing created during the summer may be far less ideal or even dangerous for the same area during winter. Likewise, pedestrian interactions are not identical throughout the year and may be impacted by these timings. Drivers build expectations of how intersections, particularly ones near their home, tend to operate, so season or situation specific timing may actually create accidents around the change boundaries. This is a problem that you can easily over optimize for and one that is difficult to measure the "full system" impacts of.
- DistractionRect 3y ago
  This. When they changed the timing of my usual intersection it caught me by surprise (and just entering the intersection on when it turned red). Thankfully no one on the cross street was trigger happy, but I can anecdotally attest that I was accustomed to a much longer yellow and behaved accordingly. I do believe that's why most accidents occur close to home, we develop expectations and operate on them, blindsided when conditions change without warning. But... to play devil's advocate, it's hard to develop expectations from a dynamic system, as it's operation is constantly changing/adapting to conditions.
  - zonkerdonker 3y ago
    Was there a new red light camera set up at the intersection recently? The city-contracted companies in charge of the cameras alter the yellow light duration to increase ticket revenue supposedly
    - DistractionRect 3y ago
      Nope. There are cameras, but that's presumably for license plate tracking. It's been nearly a month, so I can comfortably say it's not a red light camera.
  - rbanffy 3y ago
    > no one on the cross street was trigger happy A green light is by no means a permission to blindly accelerate. This is something that needs to be hammered in during driving lessons.
SoftTalker 3y ago
From what I've seen, roundabouts/traffic circles work just as well. They naturally prioritize traffic in the heaviest direction without needing any power or technology at all.
- rawgabbit 3y ago
  The mayor of Carmel IN is my hero. He replaced over a hundred traffic lights with roundabouts. https://www.cnbc.com/2023/08/16/why-roundabouts-are-so-uncommon-in-the-us.html https://www.cnbc.com/2023/08/16/why-roundabouts-are-so-uncom...
- bsder 3y ago
  > From what I've seen, roundabouts/traffic circles work just as well. They do not. Traffic circles work best for diffuse, medium-level traffic that appears continuously without burstiness and is roughly even to all exits. When you have "rush hour overload on one direction" (which describes 90% of the US intersections with problems) traffic circles range from worthless to actively harmful. Traffic lights work much better in those situations. And, at other intersections, anything will work including removing traffic controls. Traffic engineering is all about tradeoffs.
function_seven 3y ago
The city I live in is just about perfect with the light-controlled intersections. Seriously, I love this place. A few reasons: 1. At night, many of the intersections here go red for all directions, and will immediately turn green for a car as it approaches. If you're going the speed limit, you don't even need to slow down. (To be clear, it gives you a green before you would ordinarily need to start braking) 2. Protected left turn signals are only installed where they're appropriate. The last place I lived just threw them up at every single intersection in some sort of ass-covering maneuver. Here, if the intersection is low traffic and has good sight lines, then you make your left after yielding to oncoming traffic. 3. The timing is super tight. I regularly notice cross-traffic signals going to yellow just as the final car passes through the intersection. I'm not sitting there wondering, "Green for who??" 4. If I enter a protected left-turn lane while the cross traffic yellow is lit up, it'll still give me the arrow. Everywhere else I've lived, I'm "too late" and have to wait for an entire new cycle before I can go. But here, as I'm passing over the induction loop, the controller instantly queues me up before the oncoming thru traffic. I've been half-joking that I'm going to write a love letter to the municpal traffic engineering department, but I really think I should. I just keep noticing their work, especially when I see how bad it is in surrounding cities.
- nuancebydefault 3y ago
  I don't need exact location but I'd love to know what country that is.
  - function_seven 3y ago
    I'm in Southern California.
johnea 3y ago
I'm also amazed that no one has analyzed how much the additional accelration needed after unnecessary stops is contributing to our greenhouse gas emmisions. Air polution from vehicles is directly related to acceleration, this is when most fuel is burned. So I would think traffic opptimization would be a climate change prevention activity...
- ReactiveJelly 3y ago
  Well, if the negative externalities of gasoline / diesel were priced in correctly, then individuals would see the tradeoff between large / small and hybrid / ICE / EV cars, and say "yeah it'd be nice to save some of those expensive petrol if my city could unfuck its traffic." Or improve public transit
bbatha 3y ago
They’ve had the technology for a 20 years. I remember in the early 2000s my traffic engineer uncle describing a system he installed covering the major artery in their township. All of the lights were networked it would batch up people turning onto the artery then virtually guaranteeing your batch would have all greens on the artery if you stayed with in 5mph of the speed limit.
DougN7 3y ago
A buddy runs the traffic lights for a midsized city. One issue they’re running into is sensors/cameras failing after X years and not having the budget to replace them when needed. All the fancy algorithms are only as good as the data, when there is data.

callalex 3y ago

Almost all infrastructure spending is a no-brainer that puts more into the economy than it takes out, but the USA is completely allergic to it anyways. This part of infrastructure is not unique in that regard.

jacobr1 3y ago
The US spends very high amounts of money on infrastructure ... but like in many other areas gets a very poor return on that investment. We underinvest relative the both the current need and potential benefits, but it isn't because there isn't a willingness to spend.
- ethanbond 3y ago
  It’s a great investment for the landlords nearby! https://en.wikipedia.org/wiki/Henry_George_theorem?wprov=sfti1 https://en.wikipedia.org/wiki/Henry_George_theorem?wprov=sft...
- outside1234 3y ago
  and it gets a very poor return on investment because it is done inefficiently - think of the 60 foot wide roads and everything else you have seen.
- zmgsabst 3y ago
  The US spends high amounts on everything from infrastructure to healthcare to education to anti-poverty. The gaslighting that we don’t spend enough comes from the corrupt groups looting the public to deliver stupendously bad results. Most people opposed to government spending oppose that corruption and theft, not the underlying project. Eg, rail projects that are ridiculously expensive by international standards.
  - jacobr1 3y ago
    Yep, in my local area, light rail gets proposed all the time. And I'm not against it in principle. But the specific project proposals, even with their optimistic ridership numbers, pan out to something like we could buy every rider their own mid-sized sedan and pay for a personal driver for the same overall sticker-price. Figuring out the cost-effective way to deliver those kinds of project, improving state capacity, seems supremely important for the US.

6stringmerc 3y ago

I worked in a field where signals were a big component. Nationwide - the variety is quite real. It could be skilled labor. Some are mechanical switches still.

akira2501 3y ago

Light timing created during the summer may be far less ideal or even dangerous for the same area during winter. Likewise, pedestrian interactions are not identical throughout the year and may be impacted by these timings. Drivers build expectations of how intersections, particularly ones near their home, tend to operate, so season or situation specific timing may actually create accidents around the change boundaries. This is a problem that you can easily over optimize for and one that is difficult to measure the "full system" impacts of.

DistractionRect 3y ago
This. When they changed the timing of my usual intersection it caught me by surprise (and just entering the intersection on when it turned red). Thankfully no one on the cross street was trigger happy, but I can anecdotally attest that I was accustomed to a much longer yellow and behaved accordingly. I do believe that's why most accidents occur close to home, we develop expectations and operate on them, blindsided when conditions change without warning. But... to play devil's advocate, it's hard to develop expectations from a dynamic system, as it's operation is constantly changing/adapting to conditions.
- zonkerdonker 3y ago
  Was there a new red light camera set up at the intersection recently? The city-contracted companies in charge of the cameras alter the yellow light duration to increase ticket revenue supposedly
  - DistractionRect 3y ago
    Nope. There are cameras, but that's presumably for license plate tracking. It's been nearly a month, so I can comfortably say it's not a red light camera.
- rbanffy 3y ago
  > no one on the cross street was trigger happy A green light is by no means a permission to blindly accelerate. This is something that needs to be hammered in during driving lessons.

SoftTalker 3y ago

From what I've seen, roundabouts/traffic circles work just as well. They naturally prioritize traffic in the heaviest direction without needing any power or technology at all.

rawgabbit 3y ago
The mayor of Carmel IN is my hero. He replaced over a hundred traffic lights with roundabouts. https://www.cnbc.com/2023/08/16/why-roundabouts-are-so-uncommon-in-the-us.html https://www.cnbc.com/2023/08/16/why-roundabouts-are-so-uncom...
bsder 3y ago
> From what I've seen, roundabouts/traffic circles work just as well. They do not. Traffic circles work best for diffuse, medium-level traffic that appears continuously without burstiness and is roughly even to all exits. When you have "rush hour overload on one direction" (which describes 90% of the US intersections with problems) traffic circles range from worthless to actively harmful. Traffic lights work much better in those situations. And, at other intersections, anything will work including removing traffic controls. Traffic engineering is all about tradeoffs.

function_seven 3y ago

The city I live in is just about perfect with the light-controlled intersections. Seriously, I love this place. A few reasons: 1. At night, many of the intersections here go red for all directions, and will immediately turn green for a car as it approaches. If you're going the speed limit, you don't even need to slow down. (To be clear, it gives you a green before you would ordinarily need to start braking) 2. Protected left turn signals are only installed where they're appropriate. The last place I lived just threw them up at every single intersection in some sort of ass-covering maneuver. Here, if the intersection is low traffic and has good sight lines, then you make your left after yielding to oncoming traffic. 3. The timing is super tight. I regularly notice cross-traffic signals going to yellow just as the final car passes through the intersection. I'm not sitting there wondering, "Green for who??" 4. If I enter a protected left-turn lane while the cross traffic yellow is lit up, it'll still give me the arrow. Everywhere else I've lived, I'm "too late" and have to wait for an entire new cycle before I can go. But here, as I'm passing over the induction loop, the controller instantly queues me up before the oncoming thru traffic. I've been half-joking that I'm going to write a love letter to the municpal traffic engineering department, but I really think I should. I just keep noticing their work, especially when I see how bad it is in surrounding cities.

nuancebydefault 3y ago
I don't need exact location but I'd love to know what country that is.
- function_seven 3y ago
  I'm in Southern California.

johnea 3y ago

I'm also amazed that no one has analyzed how much the additional accelration needed after unnecessary stops is contributing to our greenhouse gas emmisions. Air polution from vehicles is directly related to acceleration, this is when most fuel is burned. So I would think traffic opptimization would be a climate change prevention activity...

ReactiveJelly 3y ago
Well, if the negative externalities of gasoline / diesel were priced in correctly, then individuals would see the tradeoff between large / small and hybrid / ICE / EV cars, and say "yeah it'd be nice to save some of those expensive petrol if my city could unfuck its traffic." Or improve public transit

bbatha 3y ago

They’ve had the technology for a 20 years. I remember in the early 2000s my traffic engineer uncle describing a system he installed covering the major artery in their township. All of the lights were networked it would batch up people turning onto the artery then virtually guaranteeing your batch would have all greens on the artery if you stayed with in 5mph of the speed limit.

DougN7 3y ago

A buddy runs the traffic lights for a midsized city. One issue they’re running into is sensors/cameras failing after X years and not having the budget to replace them when needed. All the fancy algorithms are only as good as the data, when there is data.