The two-adjacent signals causing extra traffic is something I encounter daily in Berkeley -- Ashby / Claremont & Ashby / Domingo. I probably blow an average of 5 minutes a day cause of that double intersection.
To highlight one other point from the video: You want a light to be able to clear the line built up each time. If not, flux in > flux out and that's a recipe for a growing line, which causes a traffic jam.
Many progressive cities intentionally time their lights for this for two reasons. One is to intentionally limit capacity. Once a road gets past a certain density, you end up with problems that make things astronomically worse (for example: people who "block the box" and cause everything to grind to a halt.)
The second reason: trying to incentivize people onto trains, buses, bikes, foot, etc.
Cambridge, MA does this. The light are purposefully timed to not let you travel through multiple greens on the tertiary roads in particular, less so secondary, etc.
Cambridge also gives a substantial amount of time to pedestrians as part of every cycle- no "beg button", because the city does not consider someone on foot to be less deserving of crossing time - specifically to not have the car "be king". By making it relatively fast to get around on foot, they reduce the incentive to drive.
They also heavily structure the residential neighborhood streets with one-way directions designed to make it very difficult to use the streets people live on as cut-throughs when the main roads jam up because that leads to noise, pollution, and danger to people on foot and bike, particularly because the kind of person to use a neighborhood as a cut-through is likely also driving quickly and aggressively.
Exactly, a road system as a whole has a certain capacity and friction in the system is used intentionally to maintain order. It is a bit like limiting electrical current using resistors in electrical circuits. Sure you could leave them out, but then you will have problems.
efavdb · · focus · HN ↗
To highlight one other point from the video: You want a light to be able to clear the line built up each time. If not, flux in > flux out and that's a recipe for a growing line, which causes a traffic jam.
KennyBlanken · · focus · HN ↗
The second reason: trying to incentivize people onto trains, buses, bikes, foot, etc.
Cambridge, MA does this. The light are purposefully timed to not let you travel through multiple greens on the tertiary roads in particular, less so secondary, etc.
Cambridge also gives a substantial amount of time to pedestrians as part of every cycle- no "beg button", because the city does not consider someone on foot to be less deserving of crossing time - specifically to not have the car "be king". By making it relatively fast to get around on foot, they reduce the incentive to drive.
They also heavily structure the residential neighborhood streets with one-way directions designed to make it very difficult to use the streets people live on as cut-throughs when the main roads jam up because that leads to noise, pollution, and danger to people on foot and bike, particularly because the kind of person to use a neighborhood as a cut-through is likely also driving quickly and aggressively.
atoav · · focus · HN ↗