3 ms·

> Actuated signal control [...] inductive loop sensors embedded into the road surface It blows my mind how many people don't realize that's what those circle

> Actuated signal control [...] inductive loop sensors embedded into the road surface It blows my mind how many people don't realize that's what those circles near the stop bar of an intersection are for, and will then stop 3+ car lengths behind the stop bar, and then can't figure out why the light is never going green. > two signals closely spaced in a row on a major roadway. If one signal gives a green but the next one doesn’t, cars can back up This is a major problem at an intersection near me that I used to have to drive through frequently. Two intersections, only about 500 feet between them, and MOST traffic during rush out coming from just one of the directions, yet the lights were often exactly out of sync. The first light would be red while the next one was green. Then the first would go green while the other went red, and traffic would only move about 500 feet then stop for 2 minutes. The backup would last well over a mile. > The obvious next step in efficiency is coordination of most or all the signals within a traffic network. This is the job of adaptive signal control technologies, or ASCT. [..] These types of systems can dramatically reduce congestion My cynical ass would not be surprised at all if oil/gas companies were lobbying against ASCT because idling cars are buying more fuel. Wouldn't be too hard to convince people that an ASCT would cost too much to implement while not producing significant traffic benefits.

at1as 5d ago
> This is a major problem at an intersection near me that I used to have to drive through frequently. Two intersections, only about 500 feet between them In San Francisco (as well as other cities I've lived in) they put police in the middle of intersections during rush hour to guide traffic (i.e., stop cars before they drive into an intersection that they'll get stuck in the middle of). Seems woefully inefficient
- bluGill 5d ago
  When traffic is really heavy humans are better than machines at getting traffic through. However they cost a lot of money and so are only rarely worth the cost.
- WalterBright 5d ago
  The traffic cops greatly improve throughput. Imagine how much gas would be saved if the city spent a little effort on the traffic lights.
  - andrepd 5d ago
    How much gas would be saved by turning half of each 4-lane stroad into a bike lane! :)
mlaretallack 5d ago
ASCT is standard practice (and has been standard practice) on most junctions in most towns and cities in the UK for over 20 years.
- Sohcahtoa82 5d ago
  Curious...in the UK, is the implementation of something like that done by government employees? In the USA, a significant amount of tax-funded infrastructure is actually built out by contractors, which means there's profit going to a corporation, and there's often a cynical idea that the contracts go out to whoever will send a kickback in the form of a campaign contribution to whoever makes the decision on which contractor to use.
  - mlaretallack 5d ago
    The local councils (local Authority) usually get external companies to design the systems, but there are standard, off the shelf solutions that are specified to be used. These systems range from time synced junctions (with Vehicle attenuation) up to full Urban Traffic Control systems, the protocols used are mostly standard (UTMC), so the local Authority just needs to say what they need. For a UTC system it used to be that the council would run the instation, but with cloud computing, that's mostly run for them now as a hosted system. Usually this is all controlled by the standard local council procurement rules, and run by council employees not elected officials. The elected officials can say a scheme is needed and approve costs, but not who does it.
mock-possum 5d ago
If I had a nickle for every time I’ve had to get out of my car and walk up to the person in front of me and explain that they need to pull forward for the light to change - I’d have two nickels, yadda yadda yadda.
toast0 5d ago
> My cynical ass would not be surprised at all if oil/gas companies were lobbying against ASCT because idling cars are buying more fuel. Wouldn't be too hard to convince people that an ASCT would cost too much to implement while not producing significant traffic benefits. I don't think you need a vast conspiracy to point out that connecting traffic signals costs more (fancier signal equipment, running cable, maintaining the cables, etc) and the benefits may be subtle, hard to predict, and maybe even hard to measure. Additionally, you have a lot of people that would prefer to slow traffic. Depending on local culture, investing in traffic control can be difficult (although upgrading traffic signal systems may be better able to accomodate priority for transit and bicycle detection)

at1as 5d ago

> This is a major problem at an intersection near me that I used to have to drive through frequently. Two intersections, only about 500 feet between them In San Francisco (as well as other cities I've lived in) they put police in the middle of intersections during rush hour to guide traffic (i.e., stop cars before they drive into an intersection that they'll get stuck in the middle of). Seems woefully inefficient

bluGill 5d ago
When traffic is really heavy humans are better than machines at getting traffic through. However they cost a lot of money and so are only rarely worth the cost.
WalterBright 5d ago
The traffic cops greatly improve throughput. Imagine how much gas would be saved if the city spent a little effort on the traffic lights.
- andrepd 5d ago
  How much gas would be saved by turning half of each 4-lane stroad into a bike lane! :)

mlaretallack 5d ago

ASCT is standard practice (and has been standard practice) on most junctions in most towns and cities in the UK for over 20 years.

Sohcahtoa82 5d ago
Curious...in the UK, is the implementation of something like that done by government employees? In the USA, a significant amount of tax-funded infrastructure is actually built out by contractors, which means there's profit going to a corporation, and there's often a cynical idea that the contracts go out to whoever will send a kickback in the form of a campaign contribution to whoever makes the decision on which contractor to use.
- mlaretallack 5d ago
  The local councils (local Authority) usually get external companies to design the systems, but there are standard, off the shelf solutions that are specified to be used. These systems range from time synced junctions (with Vehicle attenuation) up to full Urban Traffic Control systems, the protocols used are mostly standard (UTMC), so the local Authority just needs to say what they need. For a UTC system it used to be that the council would run the instation, but with cloud computing, that's mostly run for them now as a hosted system. Usually this is all controlled by the standard local council procurement rules, and run by council employees not elected officials. The elected officials can say a scheme is needed and approve costs, but not who does it.

mock-possum 5d ago

If I had a nickle for every time I’ve had to get out of my car and walk up to the person in front of me and explain that they need to pull forward for the light to change - I’d have two nickels, yadda yadda yadda.

toast0 5d ago

> My cynical ass would not be surprised at all if oil/gas companies were lobbying against ASCT because idling cars are buying more fuel. Wouldn't be too hard to convince people that an ASCT would cost too much to implement while not producing significant traffic benefits. I don't think you need a vast conspiracy to point out that connecting traffic signals costs more (fancier signal equipment, running cable, maintaining the cables, etc) and the benefits may be subtle, hard to predict, and maybe even hard to measure. Additionally, you have a lot of people that would prefer to slow traffic. Depending on local culture, investing in traffic control can be difficult (although upgrading traffic signal systems may be better able to accomodate priority for transit and bicycle detection)