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no, traffic lights are efficiency. Traffic is easily modeled as buffers and context switching. As traffic flows through an intersection, the buffer for that di

no, traffic lights are efficiency. Traffic is easily modeled as buffers and context switching. As traffic flows through an intersection, the buffer for that direction drains. When it switches, there is a penalty to context switch (the traffic must come to a stop, some traffic must finish through the intersection). The perpendicular buffer (which has been filling), requires the intersection to clear completely before proceeding. Then its buffer can empty. 4-way stop signs introduce context switching for every car (the intersection must clear before proceeding) and you must stop every intersection, buffer stalls. Round-abouts ensure more rapid context switching (only wait for the car to your left to clear), no waiting for an empty buffer to continue to be empty, and fewer buffers per intersection (think left turn buffer, right turn buffer).

pmontra 4y ago
Efficiency, well... Sometimes / somewhere they seem set up to maximize driving time and pollution by turning the next light to red when one has just gone green. I wish they could use computer vision to turn traffic lights to red only when two cars approach the intersection from perpendicular directions.
- abfan1127 4y ago
  traffic lights in my old city did just that. Cameras monitored intersections and switched lights accordingly.
trgn 4y ago
> no, traffic lights are efficiency. That's exactly what I said. Traffic lights for governing car traffic are the result of a modernist obsession with efficiency; in this case a pre-occupation with car travel speeds, throughput, ... as if these are the only things that matter. I gather you view that as a positive, but I see it as a very impoverished monomaniacal mindset. That technocratic value system has poisoned (literally and figuratively) the public realm. We need less of it.
- abfan1127 4y ago
  travel speeds and throughput aren't necessarily related. Recall that car spacing is usually instructed to be "2s". the throughput is 1 car/2s. thats regardless of speed. Speed dictates the length of the yellow light, often about 1s for every 10mph, but the actual throughput is the same regardless of speed.
hedora 4y ago
> no, traffic lights are efficiency. Yes, but: https://xkcd.com/277/ https://xkcd.com/277/ Around here, typical light cycles are 2-3 minutes, and intersections often sit idle for 60+ seconds. When there are power outages, and the lights switch to four way stop mode (blinking red), traffic usually improves. Also, the California state government has basically mandated programs that intentionally increase congestion. They call it traffic quiescing, or say they want to reduce commute miles driven per year. No, they aren't providing meaningful improvements to public transit or bike safety.

pmontra 4y ago

Efficiency, well... Sometimes / somewhere they seem set up to maximize driving time and pollution by turning the next light to red when one has just gone green. I wish they could use computer vision to turn traffic lights to red only when two cars approach the intersection from perpendicular directions.

abfan1127 4y ago
traffic lights in my old city did just that. Cameras monitored intersections and switched lights accordingly.

trgn 4y ago

> no, traffic lights are efficiency. That's exactly what I said. Traffic lights for governing car traffic are the result of a modernist obsession with efficiency; in this case a pre-occupation with car travel speeds, throughput, ... as if these are the only things that matter. I gather you view that as a positive, but I see it as a very impoverished monomaniacal mindset. That technocratic value system has poisoned (literally and figuratively) the public realm. We need less of it.

abfan1127 4y ago
travel speeds and throughput aren't necessarily related. Recall that car spacing is usually instructed to be "2s". the throughput is 1 car/2s. thats regardless of speed. Speed dictates the length of the yellow light, often about 1s for every 10mph, but the actual throughput is the same regardless of speed.

hedora 4y ago

> no, traffic lights are efficiency. Yes, but: https://xkcd.com/277/ https://xkcd.com/277/ Around here, typical light cycles are 2-3 minutes, and intersections often sit idle for 60+ seconds. When there are power outages, and the lights switch to four way stop mode (blinking red), traffic usually improves. Also, the California state government has basically mandated programs that intentionally increase congestion. They call it traffic quiescing, or say they want to reduce commute miles driven per year. No, they aren't providing meaningful improvements to public transit or bike safety.