Also for pedestrian crossings, tear up the button controlled lights and put in a zebra crossing. Those are so much faster. No need for the pedestrian to wait (nor scramble across in a panicked hurry, if they are old or disabled), no timer keeping the cars waiting after the pedestrian already crossed, and no pressed buttons which operate the lights after the pedestrian has gone
Study: Traffic lights should respond to cars, not the other way around
61–70 of 75 posts
Re: Study: Traffic lights should respond to cars, not the other way around
#62A sort of vague way to do the green wave, but okay I guess. But -- and I say this in all seriousness -- one of my PhD graduate students had a far more interesting and elegant technique five years ago. In short: each car has a piggy bank. As you're sitting at a red traffic light, it dispenses tokens into your piggy bank. When you go through a green traffic light you have to give some tokens back. Here's the catch: whe…
It's a good idea but would really require the car to have interaction with the system, or the system to read and interpret individual cars (to assign the token). I think the advantage with the system shown is they are only measuring throughput rather than keeping tabs on individual cars. Thus I assume it's an easier problem to solve.
Well yes and no. Our proposal wasn't to keep tabs on cars. There's no tracking whatsoever. Lights have no idea of knowing where you have been or who you are: you're just telling them how much pain you've been suffering in the near past. The tokens aren't marked -- they're simply currency so to speak.
The approach does require two-way communication between cars and nearby traffic lights. But the approaches that various people are suggesting, including this article, largely rely on communication as well: just one-way. The lights generally need to be able to detect cars approaching and at quite a distance. This requires the cars announcing their presence: either the lights have a sophisticated sensor system (lots of plates in the road, or a vision system) or -- more likely -- the cars need to have beacons installed which let the lights know they're coming. A great many of these methods also benefit from knowing not only that cars are approaching but where they intend to go -- are they going to turn left or right or straight -- well before they get into their lanes. This requires additional signaling.
What Gabriel Balan picked up on, is that to make the system fairer and more efficient, you need to be able to transfer historical information from light to light. Not only information about how many cars are coming, but what their previous histories were. If you don't want the lights communicating with one another -- essentially tracking your car -- you can do what he did: have the cars build up a history on their own and relay that to the lights as they approach them.
Re: Study: Traffic lights should respond to cars, not the other way around
#63Earlier quoted context omitted.
It's a good idea but would really require the car to have interaction with the system, or the system to read and interpret individual cars (to assign the token). I think the advantage with the system shown is they are only measuring throughput rather than keeping tabs on individual cars. Thus I assume it's an easier problem to solve.
Yeah, for a lesser investment than that, they could put some basic sensors on so I'm not waiting with 10 other cars while a green light stays on 30 seconds in the other direction for absolutely nobody. "Improving traffic lights" is pretty low-hanging fruit.
That's already been done.
Re: Study: Traffic lights should respond to cars, not the other way around
#64"Traffic lights should respond to cars, not the other way around"
True, but believe it or not it is incredibly difficult to get right.
I'm on my local council and we recently did some prep work to look into adding "AI" to the towns traffic lights.
Here is the problem; you have to do a significant portion of the lights - or it actually gets worse. A stupid amount of planning goes into light sequencing (at least it does here....) on a macro-scale - so all of the towns lights are pretty much synced to optimize traffic flow as much as possible.
Imagine doing that on the fly for the entire town.
What ''has'' been suggested, and looks good, is a sort of hybrid approach - where traffic levels are monitored and a number of different optimized sequences used to clear traffic jams as appropriate. Even this is a pain because it is essentially the same as replacing the towns system three or four times over :)
And we are lucky in having a medium sized town with large areas of uninhabited farmland (read little traffic) around it.
Not that it isn't a good idea - but I don't think it is a very simple option.
Re: Study: Traffic lights should respond to cars, not the other way around
#65Radical, but there's only one word needed here. ROUNDABOUT. Build some.
I live in a small midwestern town that has recently taken to the idea of roundabouts. At first, I was extremely pleased (having good experiences with them in Paris/French HW systems) but I quickly became discouraged when I realized that 90% of drivers had no idea what they were doing. I now avoid certain routes through town because I'm afraid of getting in an accident.
Ugh. If there's one thing that the French road system does badly, it's roundabouts.. Firstly, they have the weird idea of having two types - roundabouts that have traffic entering into the roundabout giving way to the traffic already on the roundabout, and then roundabouts where the traffic entering has priority over the traffic already on the roundabout. Some roundabouts of the second type have traffic lights on the roundabout.
And who hasn't seen photos of the traffic on Etoile (the roundabout that goes around the Arc de Triomphe)? Nightmare! All of those stories people tell abot Etoile are true - I sometimes go up there on foot so that guests can see the arc de triomphe up close, and I see an accident about once in every three trips. Insane.
Re: Study: Traffic lights should respond to cars, not the other way around
#66"Traffic lights should respond to cars, not the other way around" True, but believe it or not it is incredibly difficult to get right. I'm on my local council and we recently did some prep work to look into adding "AI" to the towns traffic lights. Here is the problem; you have to do a significant portion of the lights - or it actually gets worse. A stupid amount of planning goes into light sequencing (at least it doe…
And let's not get into "intelligent pressure pads". The number of times I've had to run a red light at night because the pad doesn't register my bicycle...
Re: Study: Traffic lights should respond to cars, not the other way around
#67Here in downtown Seattle the traffic lights are timed for pedestrians. One can walk from one end of the city to the other without waiting for a light to change.
Re: Study: Traffic lights should respond to cars, not the other way around
#68Shouldn't lights be optimized first to reduce accidents? I've always understood inefficiency to be an intentional safety feature.
Keep all lights red. Nobody moves, pretty simple heuristic solves for reducing automobile accidents.
Maybe the ideal is that there are signals that permit bicycles and pedestrians, but if cars want to go they have to get out and push a button to get the light to let them through.
Re: Study: Traffic lights should respond to cars, not the other way around
#69Earlier quoted context omitted.
That's a bare assertion, and the link doesn't support it. There's a very important vehicle missing from the list: trucks. Add "cargo" to "people" and, suddenly, it's no longer easy to measure. How many cars are carrying cargo in addition to persons, thereby being partially a truck in function?
How many car trips include more cargo than can be carried on a bus or on a bike?
Of my single-occupancy trips, 100%.
The important distinction is that a car is a "place for my stuff."[1] I carry tools[1], erythritol, and emergency[2] preparedness items, at the very least. My largest car carries enough of a subset of my home that it's even a comfortable place to sleep, if need be.
I could certainly do without, but, having done so in the past, it's not worth it. Similarly, carrying a large enough subset on a bike, bus, or both, as I've done when I bike commuted, was a constant annoyance. Routinely/exclusively bicycling also requires additional cargo in the form of lights, locks, and minor repair tools.
[1] cf the late, great George Carlin
[2] As with my usage of "cargo," this is general, including such things as laptop.
[3] In California, we call them "earthquake"
Re: Study: Traffic lights should respond to cars, not the other way around
#70Earlier quoted context omitted.
That's a bare assertion, and the link doesn't support it. There's a very important vehicle missing from the list: trucks. Add "cargo" to "people" and, suddenly, it's no longer easy to measure. How many cars are carrying cargo in addition to persons, thereby being partially a truck in function?
Most freight does not need to move during peak traffic flow, and of course much of it already does. I'd be curious to hear your speculation about how much cargo is actually move by cars during peak traffic volume.
Don't confuse "freight" with cargo, which I use to include everything that's physical stuff.
I don't have a guess as to the magnitude, but, anecdotally, even[1] at peak commute times, I see plenty of dedicated delivery vehicles, as well as people visibly carrying something large and bulky, such as sports equipment[2], changes of clothes, baby stuff[3], and gardening tools.
I wouldn't at all be surprised if the vast majority of peak commute trips are just trying people going "from point A to point B," but even a single, unpredictably time, cargo-carrying trip per week for a particular individual is adequate incentive for having the cability the rest of the time.
[1] or especially, since that's mostly when I'm moving slowly enough to gaze at other vehicles at length.
[2] a friend of mine commuted by train and/or bike for a while and eventually abandoned it, in part, because it meant he could no longer play ice hockey mid-day on workdays.
[3] strollers and diaper bags I've come to recognize, and, if one can extrapolate from child safety seats, there are even more unseen.