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Yes, we are programmers, and are philosophically inclined to solve things through clever centralization. That doesn't mean it's the only, or the optimal soluti

by dalke 11y ago

Yes, we are programmers, and are philosophically inclined to solve things through clever centralization. That doesn't mean it's the only, or the optimal solution. Roundabouts depend on decentralized control to achieve very similar goal. (Though without, by the way, the pretty nasty failure modes should that box, or the power, go down.) It's all handwaving without experimental studies and economic analysis. The numbers for roundabout are much better established than the smart systems, which are still experimental in nature. For that matter, how much is that cost? The proposal at http://readwrite.com/2014/01/22/ai-traffic-lights-intelligent http://readwrite.com/2014/01/22/ai-traffic-lights-intelligen... is "$20,000 to $40,000 per intersection" for 'a box with a computer in it'. From http://safety.fhwa.dot.gov/intersection/innovative/roundabouts/case_studies/fhwasa09018/ http://safety.fhwa.dot.gov/intersection/innovative/roundabou... , "The average construction cost of roundabouts is estimated at approximately $250,000". That gets its numbers from http://www.fhwa.dot.gov/publications/research/safety/00067/00067.pdf http://www.fhwa.dot.gov/publications/research/safety/00067/0... which says: > Recent roundabout projects in the United States have shown a wide range in reported construction costs. Assuming “1998 U.S. Dollars” in the following examples, costs ranged from $10,000 for a retrofit application of an existing traffic circle to $500,000 for a new roundabout at the junction of two State highways. National Cooperative Highway Research Program (NCHRP) Synthesis 264 (3) reports that the average construction cost of 14 U.S. roundabouts, none being part of an interchange, was approximately $250,000. This amount includes all construction elements, but does not include land acquisition. Elsewhere I gave links to places which said the installation costs for a roundabout were more expensive than signals. I don't know if the extra 5-10% price of the "box with a computer" changes the balance. I tried to get numbers for the cost of a intersection. from http://azdot.gov/business/engineering-and-construction/traffic/faq/pros-and-cons-of-traffic-signals http://azdot.gov/business/engineering-and-construction/traff...: > A modern signal can cost taxpayers between $80,000 and $100,000 to install, depending on the complexity of the intersection and the characteristics of the traffic using it. On top of this, there is the perpetual cost of the electrical power consumed in operating a signalized intersection 24 hours a day. This cost now averages about $1,400 per year. However, that appears to be for the dumb light, and not one with 'cameras and network connections' or even magnetic sensors. From http://www.masslive.com/news/index.ssf/2009/02/450000_traffic_light_cost_eyed.html http://www.masslive.com/news/index.ssf/2009/02/450000_traffi... : > A request to spend $450,000 to install a new traffic signal on Easthampton Road remains an option for the City Council. > And while the price tag might seem high for one traffic light, city officials insist that's the going rate to design and install such an item. > "They're smarter controllers than they ever were in the past," Department of Public Works Superintendent William D. Fuqua said yesterday. It's definitely not clear to me that the high-tech, interconnected system you desire is cheaper or more effective than roundabouts. (Again, there are clearly place where signals are more effective. I am not saying to only use rounabouts.) I would be happy to read any evidence you have which says otherwise. This also means I don't think you can call out "environmentalists" for not yet pushing for your high-tech dream to come to fruition. Mind you, some of those environmentalists are pushing for "complete streets", which is yet another way to achieve comparable goals of more effective use of public roads.

WalterBright 11y ago
Since your own figures show it is cheaper, especially since the lights, cameras, and network connections are already installed and paid for, I don't understand what more evidence you need. As for their efficacy, the anecdote I posted shows there's plenty of low hanging fruit that would substantially improve things, even without an AI.
- dalke 11y ago
  Let me correct what appears to be a miscommunication. The numbers I gave don't prove anything, other than show that there is a huge range in cost, depending on the intersection type. You say "the lights, cameras, and network connections are already installed and paid for", but how many intersections are that way? More specifically, the numbers I showed are that a fully equipped signal, like what you want, costs $450,000, while a roundabout is cheaper. If all lights already have "lights, cameras, and network connections" then it's a sunken cost. If 1% of the signals are that way, then it's entirely different. I certainly don't know how interconnected the lights are. But even with hard numbers - and you haven't made any claims to any numbers - that's only a part of the point. (FWIW, the best numbers I found are from http://readwrite.com/2014/01/22/ai-traffic-lights-intelligent http://readwrite.com/2014/01/22/ai-traffic-lights-intelligen... which says "According to el-Tantawy, many of today’s traffic lights at intersections operate based on pre-programmed repeated cycles that run with little or no input from fluctuations in traffic.". That's not really helpful, other than to show there are a lot of dumb signals in the US.) Yes, construction is cheaper on average for signals, but bear in mind that signals with 'lights, cameras, and network connections' are definitely not average signals. But construction is only part of the cost-benefit analysis. The signals need to be powered, and replaced about every 10 years according to one of the URLs I gave. Roundabouts have a 25 year lifetime. Roundabouts are also safer, so there the benefits to human life must be included. And as I pointed out, you also have to consider the failure modes. Sure, yes, there's 'low hanging fruit' (which is a misnomer, as the really 'low hanging fruit', like traffic light coordination and in-pavement detectors, have long since been picked). But that's because you have a goal in mind, which is to "improve traffic signals", not "improve traffic systems" (which roundabouts do), or "improve quality of life" (which 'complete streets' and livable community advocates want to do). Thus, if you think that '"The reductions of 40 percent in vehicle wait time, nearly 26 percent in travel time and 21 percent in projected vehicle emissions realized in this pilot are remarkable,"' is a good justification, then you have to compare it to other solutions which achieve or improve upon those same goals, and not just cherry-pick (again with the fruit metaphors!) the numbers that best support your goal. As I also pointed out, the pathway to more roundabouts isn't to wholescale replace existing signals, but to use them for new intersections, and for those with high accident rates where it's most worthwhile to switch. The over time, as the old signals need replacing, switch many of them to roundabouts. That too "would substantially improve things, even without an AI".

by dalke 11y ago

WalterBright 11y ago

Since your own figures show it is cheaper, especially since the lights, cameras, and network connections are already installed and paid for, I don't understand what more evidence you need. As for their efficacy, the anecdote I posted shows there's plenty of low hanging fruit that would substantially improve things, even without an AI.

dalke 11y ago
Let me correct what appears to be a miscommunication. The numbers I gave don't prove anything, other than show that there is a huge range in cost, depending on the intersection type. You say "the lights, cameras, and network connections are already installed and paid for", but how many intersections are that way? More specifically, the numbers I showed are that a fully equipped signal, like what you want, costs $450,000, while a roundabout is cheaper. If all lights already have "lights, cameras, and network connections" then it's a sunken cost. If 1% of the signals are that way, then it's entirely different. I certainly don't know how interconnected the lights are. But even with hard numbers - and you haven't made any claims to any numbers - that's only a part of the point. (FWIW, the best numbers I found are from http://readwrite.com/2014/01/22/ai-traffic-lights-intelligent http://readwrite.com/2014/01/22/ai-traffic-lights-intelligen... which says "According to el-Tantawy, many of today’s traffic lights at intersections operate based on pre-programmed repeated cycles that run with little or no input from fluctuations in traffic.". That's not really helpful, other than to show there are a lot of dumb signals in the US.) Yes, construction is cheaper on average for signals, but bear in mind that signals with 'lights, cameras, and network connections' are definitely not average signals. But construction is only part of the cost-benefit analysis. The signals need to be powered, and replaced about every 10 years according to one of the URLs I gave. Roundabouts have a 25 year lifetime. Roundabouts are also safer, so there the benefits to human life must be included. And as I pointed out, you also have to consider the failure modes. Sure, yes, there's 'low hanging fruit' (which is a misnomer, as the really 'low hanging fruit', like traffic light coordination and in-pavement detectors, have long since been picked). But that's because you have a goal in mind, which is to "improve traffic signals", not "improve traffic systems" (which roundabouts do), or "improve quality of life" (which 'complete streets' and livable community advocates want to do). Thus, if you think that '"The reductions of 40 percent in vehicle wait time, nearly 26 percent in travel time and 21 percent in projected vehicle emissions realized in this pilot are remarkable,"' is a good justification, then you have to compare it to other solutions which achieve or improve upon those same goals, and not just cherry-pick (again with the fruit metaphors!) the numbers that best support your goal. As I also pointed out, the pathway to more roundabouts isn't to wholescale replace existing signals, but to use them for new intersections, and for those with high accident rates where it's most worthwhile to switch. The over time, as the old signals need replacing, switch many of them to roundabouts. That too "would substantially improve things, even without an AI".