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Light Traffic

senseable.mit.edu

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Re: Light Traffic

#101

Post by madeofpalk »

jakecopp wrote: post #57
maxander wrote: post #41

So a system that requires all vehicles on the road to have flawless sensor and communications systems can achieve some improvement over current-day technology (from the paper, approximately a "doubling of capacity" for intersections with this implemented.) This is a profoundly uninteresting result, given the current-day technology in question is "a dozen lights attached to a timer." Add devices that are several order…

What I don't understand is why every traffic light doesn't have cameras and some image recognition/machine learning (whether local or remote) to improve the timing - it would be such a cheap and easy fix compared to putting a sensor in each car.

Sydney actually developed an integrated traffic light system titled "Sydney Coordinated Adaptive Traffic System" (SCATS) which has been exported around the world. It adjusts timing of traffic light systems using a variety of sensors - if a bus is running late it will affect the phasing to give it more green lights to try and get it back on time.

https://en.wikipedia.org/wiki/Sydney_Coordinated_Adaptive_Tr...

Re: Light Traffic

#102

Post by lobster_johnson »

jakecopp wrote: post #57
maxander wrote: post #41

So a system that requires all vehicles on the road to have flawless sensor and communications systems can achieve some improvement over current-day technology (from the paper, approximately a "doubling of capacity" for intersections with this implemented.) This is a profoundly uninteresting result, given the current-day technology in question is "a dozen lights attached to a timer." Add devices that are several order…

What I don't understand is why every traffic light doesn't have cameras and some image recognition/machine learning (whether local or remote) to improve the timing - it would be such a cheap and easy fix compared to putting a sensor in each car.

This is usually called adaptive traffic control, and has been implemented (minus machine learning, I'm guessing) in a bunch of places, including a part of New York City [1] and, more famously, Australia [2]. The latter system, pioneered by the city of Sydney, has been sold to other countries such as Singapore. Not sure how technologically interesting these systems are. The Sydney system was developed in the 1970s, but has been improved with more modern tech (such as cellular networking) since then.

[1] http://www.nyc.gov/html/dot/html/pr2012/pr12_25.shtml

[2] https://en.wikipedia.org/wiki/Sydney_Coordinated_Adaptive_Tr...

Re: Light Traffic

#103

Post by jakecopp »

madeofpalk wrote: post #101
jakecopp wrote: post #57

Earlier quoted context omitted.

What I don't understand is why every traffic light doesn't have cameras and some image recognition/machine learning (whether local or remote) to improve the timing - it would be such a cheap and easy fix compared to putting a sensor in each car.

Sydney actually developed an integrated traffic light system titled "Sydney Coordinated Adaptive Traffic System" (SCATS) which has been exported around the world. It adjusts timing of traffic light systems using a variety of sensors - if a bus is running late it will affect the phasing to give it more green lights to try and get it back on time. https://en.wikipedia.org/wiki/Sydney_Coordinated_Adaptive_Tr...

I believe the only car sensor for SCATS is an inductive loop so it doesn't know the amount of backed up traffic, and it was developed in the 1970s and rolled out across Australia in the 80s - it's better than a timer but I don't think it should be what the world aspires to.

That being said, I had some interesting conversations with a person who worked for Transport for NSW who said some of the signalling backend was recently improved to streamline future integration with self driving cars, I can't find a reference for this though.

Re: Light Traffic

#104

Post by DrScump »

jakecopp wrote: post #57
maxander wrote: post #41

So a system that requires all vehicles on the road to have flawless sensor and communications systems can achieve some improvement over current-day technology (from the paper, approximately a "doubling of capacity" for intersections with this implemented.) This is a profoundly uninteresting result, given the current-day technology in question is "a dozen lights attached to a timer." Add devices that are several order…

What I don't understand is why every traffic light doesn't have cameras and some image recognition/machine learning (whether local or remote) to improve the timing - it would be such a cheap and easy fix compared to putting a sensor in each car.

Magnetic loop sensors in pavement have been used to recognize vehicles at intersections for decades.

Re: Light Traffic

#105

Post by sharpercoder »

IshKebab wrote: post #49
sharpercoder wrote: post #39

Earlier quoted context omitted.

On roads where you can drive 30+MPH (50 KMPH+), I would suggest removing any possiblity for pedestrians to cross. Either make the road 20MPH (30KMPH) max where all space is shared with pedestrians, bicycles and cars - or make much better, safer & faster 50KMPH+ roads.

Is this satire? How do you walk anywhere otherwise?

If I'm in a car, I'd like to not brake-accelerate-brake-accelerate but rather move in a constant tempo. If I'm a pedestrian, I'd like a car-less safe environment to walk.

Re: Light Traffic

#106

Post by seanmcdirmid »

vinay427 wrote: post #91
mindslight wrote: post #66

Earlier quoted context omitted.

"Widely" ? Maybe in altruism-display places like SoCal, where the expectation for traffic interaction is to stop and have a ten minute meeting about how to proceed so everyone can feel leave feeling superior. In general it's just called yielding , and that it happens in all four dimensions is implicit. The difference in China is that the tolerances are smaller.

Can you elaborate on where this is coming from? I know you're exaggerating, but in my limited experience I haven't noticed abnormally long yield times at intersections in southern California.

There used to be something called a "Californian stop" that was a partial stop rather than a full stop, but after living in LA for a year, I never saw it happen.

Re: Light Traffic

#107

Post by burfog »

rcarmo wrote: post #21
ColanR wrote: post #16

Earlier quoted context omitted.

re shared spaces, from the wikipedia: > Hans Monderman and others have suggested that, by creating a greater sense of uncertainty and making it unclear who has priority, drivers will reduce their speed, in turn reducing the dominance of vehicles, reducing road casualty rates, and improving safety for other road users. clearly, Hans Monderman has never driven in Mumbai, India.

I think that shared spaces make sense in small towns, university campuses, and other contexts where traffic flow is low due to the inherent context (and, above all, where pedestrians can support each other). But for modest to high volume traffic, roundabouts are better (although if the traffic flow is constant, you usually have to place the crossings a bit further away from the center of the roundabout, which makes i…

For high traffic, a roundabout would have to be truly huge. It isn't viable unless land is practically free. You need something more like this:

https://en.wikipedia.org/wiki/High_Five_Interchange

That crosses 16 lanes with 14 lanes. (3,5,5,3 with 3,4,4,3)

Re: Light Traffic

#108

Post by nordsieck »

jakecopp wrote: post #86
jakobegger wrote: post #65

Earlier quoted context omitted.

Lots of traffic lights in my area already have sensors (induction loops to detect waiting cars or approaching bicycles, IR motion detectors to detect pedestrians). In some cases this is really useful (eg. a traffic light for a bike path does not need to switch very often in winter, so it only switches when a bike approaches) I think that the problem is that often there is too much traffic from all directions and even…

I believe the induction loops only sense if the first car is present. This is helpful, but can't detect the number of cars which I think is the next most important metric.

At busy intersections, there will typically be a loop at the 1st spot and a second loop further back - say, at the 5th spot. It's not perfect, but it's pretty good.

Re: Light Traffic

#109

Post by greeneggs »

ReverseCold wrote: post #77
IshKebab wrote: post #49

Earlier quoted context omitted.

Is this satire? How do you walk anywhere otherwise?

Maybe, but it's an interesting concept. My city put bridges over a lot of the major roads for people to cross. A few roads have a tunnels underneath as well.

I imagine you don't even have to put too many of them in, before any pedestrians give up and drive---having tired of needing to climb and descend four flights of stairs or, worse, walk an extra block along ramps, just to cross the street.

Re: Light Traffic

#110

Post by adrianmonk »

chiefofgxbxl wrote: post #47

I think people are focused on maximizing the wrong metric. Traffic projects like this tend to want to maximize car throughput , when what we really need is to minimize travel distance/time . Maybe then society would start looking at the effects that cars have made to sprawl, and the self-reinforcement cycle that emerges.

I think it is a both thing rather than an either-or thing.

As long as roads continue to exist in any form, it seems crazy not to aim for efficiency. What is to be gained by passing up opportunities to make them efficient?

So this is not a wrong metric, it is just that both metrics need to be taken into account.

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