8 ms·
Light Traffic
- niftich 9y agoThis is a cool video, but the paper itself [1] is pretty light. The substance of the paper is basically (from the abstract): "Despite simulation-based evidence of the potential benefits of SIs [Slot-based Intersections], a comprehensive, analytical framework to compare their relative performance with traffic lights is still lacking. Here, we develop such a framework." A handful of other quotes from the body examine the rationale and context for investigating this question. They compare the results of a platooning-type control strategy with a fair scheduling strategy, and the "usual", fixed-cycle strategy, and find that the platooning one, deemed 'BATCH', scales towards the optimal throughput as the number of vehicles increases. There's formulas and graphs to back this up. This is good work, but the website is a marvellous example of marketing; subtly promoting the higher implications of the work instead of the work itself. [1] http://senseable.mit.edu/papers/pdf/20160316_Tachet_etal_RevisitingStreet_PLOS.pdf http://senseable.mit.edu/papers/pdf/20160316_Tachet_etal_Rev...
- w0de0 9y agoWhat about pedestrians? For me, a future in which vehicles have more control of our public spaces is worse than the present, no matter the efficiency of the arrangement. Many American cities are notorious for being designed for the automobile, not the human. Let's not double down. More Ramblas!
- ukulele 9y agoAutonomous vehicles are far more deferential to pedestrians than human drivers. It's not even close.
- Pulcinella 9y agoHeh. I find it funny that fiction portrays machines wanting to destroy humanity. It may turn out that machines with super human reaction times, never get tired or frustrated, and have infinite patience end up being nicer people than actual people.
- seanmcdirmid 9y agoIt is kind of funny because pedestrian crossings already kind of work like this in China. The car will never ever stop for you, rather, it will adjust its speed and swerve slightly to avoid a collision (if expected, if unexpected, then its a totally different game). Likewise, the pedestrian is expected to move in a consistent direction and adjust their speed to avoid being in the way of a car. The result is that car traffic and pedestrian traffic can keep moving at the same time even when orthogonal. Of course, it often doesn't work, and it is only possible at all given the slower vehicle speeds of a congested road network. Also, the flow of pedestrians in China is rather more continuous than in America.
- zten 9y agoOddly, this is a cyclist behavior that is very widely admonished as being pedestrian-hostile.
- plandis 9y agoIn most places in the US it is unlawful for cyclists in the road not to follow traffic law. It is pedestrian hostile in the sense that people don't expect it because it is unlawful.
- seanmcdirmid 9y agoYou mean in the USA. In a cyclist-friendly country like the Netherlands, it is considered completely normal even by pedestrians.
- tinco 9y agoThat it is normal doesn't mean it's not pedestrian hostile. I catch myself cycling over-aggressively. For example, everyone knows that pedestrians have right of way on a zebra-crossing. Good luck with that in The Netherlands. Cyclists will simply not give you right of way, they'll swerve around you, ignore you, and generally make you uncomfortable. The Netherlands is a cyclists country in much the same way as the U.S. is car country, pedestrians are second class.
- perennate 9y agoCyclists are also not considered. Maybe the intersection looks like this once you add pedestrians and cyclists: https://vimeo.com/106226560 https://vimeo.com/106226560 Edit: also worth checking the earlier discussion from a couple years ago: https://news.ycombinator.com/item?id=11336009 https://news.ycombinator.com/item?id=11336009
- ilyagr 9y agoThat's an awesome video, thanks!
- yeukhon 9y agoI thought this whole sensor thing a lot in the past, specifically as an argument to criticize the state of our autonomous vehicle development. We must be very careful handling electronic failures and sensor reliability. I know someone will bring up "well, traditional car will fail and results in fatal crash too, but technology can help us catch that and predict accidents by looking at 360 degree!". True, but let's not let that promise blinds us. Also, this senor-led, slot-based system won't work in areas like NYC midtown, so not a one-size fits all solution (that's a given). If we exclude accidents and roadworks, then traffic lights, narrow roads, increase of cars on the road (due to ride-sharing and cars becoming more affordable), and double parking, they all contribute to the majority of traffic jam. Some futuristic fixes include flying cars, roads in mid-air, roads through buildings, and more underpass might help but they don't scale when you keep adding more cars. We need to improve our mass transit. If you have ever played Skyline or SimCity, you know that intersection sucks and mass transit is preferred over roads. Too many school buses will slow down traffic. Multi-lane to single-lane can jam the road. The NY subway system coverage is pretty good, but each train runs on one lane and is a single point of failure. Kudos to those working in transportation planning though...
- zhoujianfu 9y agoWhat would people give the odds we achieve a world of autonomous flying drone transport for local travel before a world of autonomous self-driving cars? It seems right now like we’re really close with self-driving cars but objectively flying ones would be a lot better: Shorter distances to travel (point to point), easier to implement collision avoidance, faster, no need for this crazy infrastructure we build/maintain of roads, bridges, traffic lights, tunnels, snow plows, street cleaners, etc...
- philipodonnell 9y agoI believe the failure modes are a bigger concern for flight-based vehicles.
- orasis 9y agoDrones are far too loud.
- icebraining 9y agoDrones don't have to be quad/octocopters. I'd love to see a self-driving electric paraplane.
- marten-de-vries 9y agoI'm curious if developments like this will mean future cars will not require lights at all. After all, the same communication required for an intelligent traffic intersection like this could just as well be used to exchange breaking, lane changing and position information.
- Spivak 9y agoI think a short summary is that the researchers are looking at proposing a few different schedulers for intersections with the aim of implementing them with autonomous cars. The results exist in ideal conditions with little thought given to real-world edge cases, what a transition might look like, how cars would coordinate, or if a square intersection is even a good shape for this kind of thing. My lingering question after reading the paper is the enforcement mechanism. Process scheduling because there's an omnipotent authority with total control over all processes but whatever system is used needs to work with no central control and if all the cars are programmed to be selfish.
- Animats 9y agoThe Stanford Cart people proposed something like that in the late 1960s/early 1970s. There may even have been a video.
- rcarmo 9y agoThere's been a marked tendency to replace intersections with roundabouts and shared spaces (https://en.wikipedia.org/wiki/Shared_space https://en.wikipedia.org/wiki/Shared_space) in many places, including the outskirts of Lisbon (as well as a few legendary mazes in Britain). There was even a BBC report on the latter (which I can't find right now, as usual, only a follow-up: http://www.bbc.com/news/uk-33303031 http://www.bbc.com/news/uk-33303031). Drawing a (admittedly inaccurate) parallel with shared spaces (which are harder to navigate by sensory deprived humans than standard intersections), I'd say roundabouts (which preserve crossings) would be a more sensible short-term approach overall -- especially considering the remaining human drivers. Full disclosure: I don't drive anymore. Gave it up decades ago because I prefer to do something useful with my commute times, and resort to public transportation or Uber whenever possible, which (ironically) allows me to arrive earlier to meetings than most of my colleagues (who need to hunt down a parking space).
- ColanR 9y agore 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.
- rcarmo 9y agoI 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 it a little harder on elderly pedestrians to go fully "across" since they have to walk the extra distance).
- ryth_ 9y agoThey actually introduced a shared space at Amsterdam Central Station about 1-2 years ago that I cross daily. The shared space is right next to the incredibly busy ferries and perpendicular to what used to be a bicycle lane. It's now one big square shared by bicycles, pedestrians and scooters. It does work incredibly well and there are rarely any accidents. The downside however is that it's quite a struggle to cross. It makes me dread to leave the ferry and enter the warzone once again every morning. I understand that it is designed to make me uncomfortable, but it is taken to such an extend that I don't even really want to walk there.
- natemurthy 9y agoThis looks like an awesome project, and I hope this receives significant attention from city planners. I imagine as cars become more connected, we'll have better interfaces for integrating mobile traffic sensors with stationary traffic sensors for optimal management of vehicle flow along congested streets. But I do worry about the pace at which city planners adopt such technology at a time when local government budgets are tight.
- IndrekR 9y agoThis is a good video example of how manufacturing works in lean factories. By reducing or avoiding inventories, fetching from temporary warehouses and machining stops (traffic lights here) you can often increase the production rate significantly.
- rcarmo 9y agoLook up "kiva warehouse robots". You'll spend an hour fascinated by modern warehousing :)
- IndrekR 9y agoThanks! Kiva/Amazon is a great real-time optimization challenge. Digikey logistics is a good example of how it is well done with non-machines: https://youtu.be/pYqzccJdgVY https://youtu.be/pYqzccJdgVY
- purplejacket 9y agoFor fucks sake, where are the pedestrians??
- tomxor 9y ago> For fucks sake, where are the pedestrians?? You're watching it wrong: It's a dystopian future in which all humans died out after years of being forced to take part in a city scale version of frogit with perma-death against autonomous vehicles.
- sharpercoder 9y agoOn 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.
- IshKebab 9y agoIs this satire? How do you walk anywhere otherwise?
- ReverseCold 9y agoMaybe, 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.
- greeneggs 9y agoI 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.
- icebraining 9y agoMake the whole city 20mph max? Fine by me :)
- ZenoArrow 9y agoWhat are the benefits of this proposal when compared to roundabouts?
- tomxor 9y agoI live in the UK where roundabouts are almost everywhere. While they are definitely more efficient than crossroads they still have some flow control issues in some scenarios: each joining road effectively controls the flow of the next joining road further along the roundabout through priority, this is both a strength (automatic flow control) and a weakness (unbalanced flow of joining roads): Imagine a simple roundabout in place of an crossroad with 4 joining roads, if only two joining roads next to each other are active and of those two, the one to the right has an endless contiguous flow, then all traffic on the road to the left is blocked - it's basically waiting for road to the right to be blocked by someone coming onto the roundabout from the next road along. As a result we have traffic lights on roundabouts as well sometimes, which prevents this unfairness but also takes them back closer to the efficiency of a crossroad. I think the best combinations would be autonomous + roundabouts, I think fast crossroads are just dangerous (autonomous or not). Roundabouts force vehicles to slow down due to the forced turn and negotiate one stream of traffic going in one direction rather than two streams going in up to 4 directions at speed. The potential injury from the later is so much higher it's a non-argument.
- ZenoArrow 9y agoI also live in the UK, so I'm familiar with roundabouts for the same reasons you are, but I'm glad you've given the explanation for those that are not. In your example, "an crossroad with 4 joining roads, if only two joining roads next to each other are active and of those two, the one to the right has an endless contiguous flow, then all traffic on the road to the left is blocked", this is a theoretical weakness, but in practice it rarely occurs. For starters, the chances of zero traffic from the other two roads is small, and "continuous" traffic is rarely busy to the level where cars from the road to the left are blocked completely. Furthermore, if such bottlenecks occur, they can be mitigated against by diverting traffic, through the addition of changes to surrounding roads. Roundabouts may not be something to be implemented without consideration to the surrounding road infrastructure, but they seem like they would be decent step forward for many busy intersections with traffic coming from multiple directions.
- vs2 9y agowont roundabouts solve the same problem today!?
- paulsutter 9y agoThis slot based system is hell for pedestrians and bicycles. Let’s put powered vehicles underground and reserve the surface for humans. “Without tunnels we’ll be in traffic hell forever” -Elon Musk
- sharpercoder 9y agoA few thoughts on this matter: 1. Roundabouts are safer and better with human drivers but bad from a usability standpoint. It's annoying to drive, slower, and makes people feel nauseous when driving through many. When we have road usage of autonomous vehicles surpassing 50%, I suggest to remove them. 2. Two-Leveled intersections without left turns seem cost effective and highly advantageous in cities. To lower the cost even further, it may be possible to design them for vehicles only (much lower ceilings needed, so much lower cost). Left turns can be achieved (especially in the US this is viable) bu going right three times (going around the block). Two-leveled intersections without left turns can reach 100% capacity in all lanes from all directions. 3. Lane-specific traffic light already may increase efficiency on intersections. Imagine a 2x2 intersection from both directions: the right turns can be green (where cars turn right on the rightmost lane) while through-traffic can use the left lane.
- mgbmtl 9y agoI feel like so many similar proposals tend to ignore how saturated our roads are, how expensive the road infrastructure maintenance is, and how fast people expect to drive (because of long commutes from endless suburbs). We need to find innovative ways to implement forms of collective transportation (rail or what not) in already dense areas. Rail/subways have already proven how effective they are. Autonomous vehicles are necessary to improve road safety, maybe they can help slightly reduce the amount space used by roads, but they won't solve most of the problems we have today on our unsustainable roads.
- acranox 9y agoThey also seem to ignore people riding on bikes, and people walking around.
- closeparen 9y agoUnsustainable compared to what? New York is clearly demonstrating that it’s incapable of sustaining a subway, and it has just about the best conditions possible for such a project. You think a place that can’t even manage roads can swing a subway? Is it sustainable to all move closer together? Not if the residents of existing cities have anything to say about how those cities are governed. They don’t want the extra population.
- notatoad 9y agounsustainable is an absolute, not a relative. A road network doesn't have to be unsustainable relative to anything in order for it to be full to capacity at and for there to be no room for any more roads, which is the situation New York finds itself in. It is physically impossible for NYC to have sustained substantial growth to their private vehicle infrastructure, hence "unsustainable". If they want to grow their transportation network, they need to do it via other modes. And i reject your assertion that New York has the best possible conditions for transportation infrastructure. A lack of space, a huge demand, and a corrupt mixture of local government and unions don't make for an idea development environment.
- 9y ago
- maxander 9y agoSo 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 orders of magnitude more expensive and yeah you'll get something better- that they only achieve a factor of two improvement (in theory!) reads as a stunning failure of autonomous vehicle technology to pull their weight in this regard. (Granted, more clever schemes might be produced that might get better results from this scenario- it's hard to prove that they can't be effective.) Better idea- instead of having the world pay for sensor/communication systems on every car, have the same sensor packages installed on the traffic lights so that they can operate in a smarter fashion. Orders of magnitude less expensive, and quite possibly as effective in reducing traffic backup.
- jakecopp 9y agoWhat 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.
- tedmiston 9y agoA sensor itself isn't expensive but moving, storing, and processing all of that data to ultimately take action is. Let alone concerns with people about being recorded in public, even if red light cameras are permitted in some states today.
- jakecopp 9y agoEven OpenCV running on a Raspberry Pi can pick out cars in a moving image - a bad offline solution (with a sensible fallback) would be better than a timer. On a large remote setup I think you are right though.
- chiefofgxbxl 9y agoI 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.
- jakecopp 9y agoI view maximizing car throughput as beneficial because it means less roads need to be built (more money for mass transit).
- ImaCake 9y agoI honestly think the real toll is the mental concentration required and the stress caused by driving a car. Self-driving cars automatically fix that problem by removing the need for the passenger to concentrate on not killing people. When I take the bus I don't worry so much about my commute time, because I spend the ride relaxing and reading.
- adrianmonk 9y agoI 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.
- ReverseCold 9y agoThis all works okay if you can trust every car on the road, but what about XYZ hacker broadcasting false information to slow everything down? Or more nefarious, they could cause an accident.
- JackFr 9y agoCurious to see how it would respond to to volumes higher than it can safely handle. Revert to traffic light?
- ramzyo 9y agoCool idea. This seems like a big caveat though, >> With today's traffic volumes, queues would vanish and travel delays would be cut to almost zero. I’m pretty sure it’s critical in traffic engineering to consider how the design would hold up in the event of larger volume given greater efficiency. There’s a single lane exit on the Mass Pike about 5 miles outside of Boston that’s always backed up onto the highway. I’d always wondered why they hadn’t added a lane, put a divider, or otherwise designed the exit differently. A few years ago a former colleague met the engineer who did the traffic analysis for that exit. Apparently adding capacity to achieve greater throughput would’ve resulted in worse traffic at the exit. According to the models they developed, the more constrained solution was actually optimal, although to the frustrated driver (me!) it still seems poorly designed. Granted, this is an example of increasing capacity rather than improving efficiency. Regardless, I’d be interested to see how the MIT solution holds up to increased traffic volume.
- adrianmonk 9y agoThese slots look way too small in the animation. Every slot needs a bit of a safety buffer. Getting t-boned is more dangerous than getting rear-ended. So it seems like they should be trying to amortize that cost by grouping cars together, both horizontally (side by side) and vertically (front to back). So in other words, have a cluster of, say, 5 or 10 cars that cross the intersection together. That can be done by adjusting the speed of cars well in advance of the intersection to group them, so it's not necessary to come to a stop as with stoplights.
- m3kw9 9y agoThey should just keep it simple, convert large intersections to massive round a-bouts.
- opensourcenews 9y agoAnd the pedestrians go where?