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Apparently my city is pondering a blanket 20 mph speed limit on almost all roads within the city. Is this a good idea?
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Mar 11, 2015 16:08
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Fangz posted:Apparently my city is pondering a blanket 20 mph speed limit on almost all roads within the city. Is this a good idea? Do they have a severe budget shortfall?
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Mar 11, 2015 16:11
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Well it's Edinburgh. "Campaigners hail Edinburgh's 20mph speed limit plan" http://gu.com/p/46dg2 I imagine they are budget constrained, but not hugely in the red.
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Mar 11, 2015 16:14
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I live in a small town (like 1500 people) that has a 20 MPH "All Town" limit. It's a pretty normal speed for a regular street, I'd think.
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Mar 11, 2015 17:12
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20 MPH is way safer for basically everybody, there's no need to be racing through the city.
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Mar 11, 2015 17:39
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Kaal posted:It's very cool looking, but I scratch my head at the idea of using the space inside the interchange. What exactly is supposed to go inside? Certainly it isn't a useful residential or commercial space. Maybe you could put in a solar field or a monument - something that doesn't need to be accessed very much - but it seems like a lot of compromises just in order to get a few acres of land that still can't be easily used. Perpetual Starbucks drive-thru, obviously.
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Mar 11, 2015 18:15
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Fangz posted:Well it's Edinburgh. As someone who walks a lot (and also drives) there, yes, it's a great idea and will make the city a much more pleasant place to be. Pedestrian experience and journey times will be significantly improved at a very slight (often non-existent) journey time penalty to motorists.
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Mar 11, 2015 18:21
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Fangz posted:Apparently my city is pondering a blanket 20 mph speed limit on almost all roads within the city. Is this a good idea? The amusing thing is that a lot of the time most of Edinburgh's roads crawl along at less than 20 anyway. loving Gorgie Road in the morning Jesus Christ.
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Mar 11, 2015 19:06
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According to that article it is not all roads but merely 80% of them. That is the case in pretty much every Dutch city. I think it works great. Costs you maybe a few seconds on a journey, the last few hundred meters are a bit slower though with the layout of most streets i wouldn't do 50kph even if that was the speed limit. Small price to pay for the increased quality of life (being able to walk places without getting killed and such).
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Mar 11, 2015 19:56
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NihilismNow posted:According to that article it is not all roads but merely 80% of them. That is the case in pretty much every Dutch city. I think it works great. Costs you maybe a few seconds on a journey, the last few hundred meters are a bit slower though with the layout of most streets i wouldn't do 50kph even if that was the speed limit. Small price to pay for the increased quality of life (being able to walk places without getting killed and such). Absolutely. Given that there will always be drivers who do 10-20km/h over the speed limit, setting limits to 30km/h (20mph) means that in the worst case you have drivers doing 40-50 (25-30) on those residential streets, rather than 60-70km/h. Seeing people do 70 down a street which could have kids, pets or seniors crossing is downright harrowing.
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Mar 11, 2015 21:53
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Well designed urban streets don't even need a specific low speed limit, they're just designed in such a way that it's basically impossible/pointless to go faster than 30-40k or so. There's just too many lights, too many people at cross walks, everything's narrow, there's poo poo moving all around you so you just have to go slow to feel at all safe. \/ In Victoria they reduced the speed limit to 40k as the default limit, which is stupid because the streets were you needed to go slower already had slower traffic because poo poo is stop and go or jammed with pedestrians. The group pushing for it had absolutely no hard data to back anything up but one of their biggest pushes was about air quality and global warming. I don't get it. The only way I can see the logic following is that by making the city safer for walking and cycling and a tiny bit slower for cars, maybe less people will drive?? Baronjutter fucked around with this message at 22:51 on Mar 11, 2015 |
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Mar 11, 2015 22:42
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It's definitely a big boon for safety, but I don't see how it would reduce pollution. Cars produce the least pollution somewhere around 45mph, and each additional stop is another emission of exhaust. Hopefully they're planning on properly coordinating their signals at the same time, or their air quality's going to get a good deal worse!
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Mar 11, 2015 22:48
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Cichlidae posted:It's definitely a big boon for safety, but I don't see how it would reduce pollution. Cars produce the least pollution somewhere around 45mph, and each additional stop is another emission of exhaust. Hopefully they're planning on properly coordinating their signals at the same time, or their air quality's going to get a good deal worse! I wonder what the data from the Netherlands says about this.
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Mar 11, 2015 22:56
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Part of Paris' war on air pollution did involve lowering speed limits, but it was a multi-pronged literal war on cars. Streets were narrowed, speed limits reduced, parking eliminated, transit increased, bike share program. They pulled out every trick in the book. All together it really worked, air quality is up and car ownership has gone from about 60% to 40% in just a few years.
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Mar 11, 2015 23:02
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Cichlidae posted:It's definitely a big boon for safety, but I don't see how it would reduce pollution. Cars produce the least pollution somewhere around 45mph, and each additional stop is another emission of exhaust. Hopefully they're planning on properly coordinating their signals at the same time, or their air quality's going to get a good deal worse! The number of stops will presumably be the same or less but the pointless acceleration beyond 20mph will go, so presumably that will help? I find this 'but nobody gets to 20 anyway!!' thing slightly silly really, because even during peak hours Edinburgh has relatively little congestion and even in quite busy traffic drivers have plenty of opportunities to hit 30mph - before, of course, they hit the back of the next queue. It's right in terms of average speed though of course - that's why there won't be so much of a journey time reduction.
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Mar 12, 2015 00:04
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Lead out in cuffs posted:I wonder what the data from the Netherlands says about this. There was a study out of England last month comparing the exposure to dangerous levels of particulate exhaust when stopped vs. moving. Air quality within cars is a lot worse than air quality outside, as you might expect, and it declines drastically when you come to a stop. I found a study through spiegel.de, which added that respiratory problems due to bad air quality is the third leading cause of death among Germans, so we're not talking small amounts of pollution. So basically, any system that requires cars to stop at all is going to cause more pulmonary death. The easy solution is to ban cars. The less disruptive solution that lets suburbanites keep their happy 1960s dream is to improve emissions standards and switch to cleaner fuels. Unfortunately, electric cars won't be a solution in countries that derive much of their electricity from fossil fuels. Another recent study showed that electric cars fed from coal plants weren't any cleaner than gasoline-burning cars.
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Mar 12, 2015 00:15
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Cichlidae posted:There was a study out of England last month comparing the exposure to dangerous levels of particulate exhaust when stopped vs. moving. Air quality within cars is a lot worse than air quality outside, as you might expect, and it declines drastically when you come to a stop. I found a study through spiegel.de, which added that respiratory problems due to bad air quality is the third leading cause of death among Germans, so we're not talking small amounts of pollution. So basically, any system that requires cars to stop at all is going to cause more pulmonary death. Lol yeah on electrical cars in places that get their electricity from coal. What with energy losses between power plant and car, you would probably produce less pollution running your car on a coal-fired steam engine. What I meant, though, was that the Netherlands has had these lowered limits in place for about 30 years or so, and I suspect that somebody would have studied whether that has had a negative impact on emissions. I'd suspect that there are other factors besides per-car pollution, like how making cycling and walking safer and more comfortable has undoubtedly reduced the number of cars on the road. Maybe the many Dutch traffic engineers in this thread could help out?
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Mar 12, 2015 00:34
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Cichlidae posted:There was a study out of England last month comparing the exposure to dangerous levels of particulate exhaust when stopped vs. moving. Air quality within cars is a lot worse than air quality outside, as you might expect, and it declines drastically when you come to a stop. I found a study through spiegel.de, which added that respiratory problems due to bad air quality is the third leading cause of death among Germans, so we're not talking small amounts of pollution. So basically, any system that requires cars to stop at all is going to cause more pulmonary death. Is this true even with modern cabin air filters? Most cars have them now (to my knowledge, anyway--I figure if my 2006 Civic had it, they must be everywhere).
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Mar 12, 2015 05:29
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On the other hand, it's a lot easier to regulate and clean up one big pollution source rather than thousands of little ones. How long does it take for efficiency improvements to trickle down to the population at large? People buying new cars now are getting the deal, but it's all of the used not-so-efficient cars that hold the share, right?
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Mar 12, 2015 09:41
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dupersaurus posted:On the other hand, it's a lot easier to regulate and clean up one big pollution source rather than thousands of little ones. Yep - and I don't think there's any developed countries that don't generate some reasonable proportion of their energy from renewable sources. Even if you're generating from 100% fossil fuels, the fact you're no longer generating pollution right in the heart of your busiest population centres is a plus too.
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Mar 12, 2015 10:14
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Kakairo posted:Is this true even with modern cabin air filters? Most cars have them now (to my knowledge, anyway--I figure if my 2006 Civic had it, they must be everywhere). Unless they're HEPA filters, they're not going to catch the smallest particles. I know I can certainly smell burnt rubber or cigarette smoke within a second or two when I'm inside my relatively new car. Jonnty posted:Yep - and I don't think there's any developed countries that don't generate some reasonable proportion of their energy from renewable sources. Even if you're generating from 100% fossil fuels, the fact you're no longer generating pollution right in the heart of your busiest population centres is a plus too. This study was specifically targeting CO2 emissions, which don't care whether they're being puffed out of a billion tailpipes or a million smokestacks; it's all going in the same place. You're definitely right about particulates, though - it's much easier to filter point sources.
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Mar 12, 2015 12:07
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Speaking of Edinburgh, I just made a thing: Imagine trying to make one for London...
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Mar 12, 2015 12:41
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I was watching some youtubes on the Edinburgh tram, it looks nice. But it seems to have been a massive boondoggle for it's construction. Now that it's done is it working as intended? How could it possibly have gone over-budget so much without either massive corruption or criminal levels of negligence/idiocy?
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Mar 12, 2015 18:14
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Baronjutter posted:I was watching some youtubes on the Edinburgh tram, it looks nice. But it seems to have been a massive boondoggle for it's construction. Now that it's done is it working as intended? How could it possibly have gone over-budget so much without either massive corruption or criminal levels of negligence/idiocy? It's easy to go over budget if your original budget wasn't exactly grounded in reality, but rather in "what cost could we get passed?" or "what would be the absolute minimum to do this project?".
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Mar 12, 2015 18:58
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Baronjutter posted:I was watching some youtubes on the Edinburgh tram, it looks nice. But it seems to have been a massive boondoggle for it's construction. Now that it's done is it working as intended? How could it possibly have gone over-budget so much without either massive corruption or criminal levels of negligence/idiocy? It's all a bit confusing, so we're having an inquiry to find out where all the money went. Its offices were recently subject to a suspiciously targeted break-in. I'll leave you to draw your own conclusions about where some of the cash might have ended up.
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Mar 12, 2015 19:16
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Nintendo Kid posted:It's easy to go over budget if your original budget wasn't exactly grounded in reality, but rather in "what cost could we get passed?" or "what would be the absolute minimum to do this project?". Other than the obvious problems of essentially lying to get a project passed knowing you'll go way over budget but then it will be too late is that then other communities end up not wanting to build such projects because "they always go 10x over budget, look at how bad Edinburgh hosed up!" Politically any transit project is assumed to go way over budget so people are very resistant to them and there's no reason for engineers to give real numbers. Everyone assumes it's a lie so you better lie anyways. your project will cost 1 billion? Say it's 500 million, the public assumes it will go double over-budget. Also is mildly accurate costing just impossible? Why do things always go so over budget? Is it because you basically have to lie to get your numbers low enough to initially get the project started? Are cities and transit authorities just really incompetent at budgeting? Are trades also low-balling to win contracts? Is there too much red-tape and liability culture that adds huge amounts of ineffective but extremely expensive studies and legal work? I assume it's a mix of everything. Obviously there's no magic bullet, but in North America if anything could be changed in this whole process to make things cheaper, what would be the top changes? Baronjutter fucked around with this message at 19:59 on Mar 12, 2015 |
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Mar 12, 2015 19:56
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Baronjutter posted:Obviously there's no magic bullet, but in North America if anything could be changed in this whole process to make things cheaper, what would be the top changes? Take all the people who decide that the lowest bid should always win the contract and dropkick them out the window.
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Mar 12, 2015 20:15
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Baronjutter posted:Other than the obvious problems of essentially lying to get a project passed knowing you'll go way over budget but then it will be too late is that then other communities end up not wanting to build such projects because "they always go 10x over budget, look at how bad Edinburgh hosed up!" Politically any transit project is assumed to go way over budget so people are very resistant to them and there's no reason for engineers to give real numbers. Everyone assumes it's a lie so you better lie anyways. your project will cost 1 billion? Say it's 500 million, the public assumes it will go double over-budget. No matter how much money the actual project cost versus the budget, people would still whine about how much was spent. Even in cases where projects finished under budget, a lot of people still whine about how much it cost. So really, why bother getting the budget right? Just get it so it will pass, and make sure there'd be negative ramifications to anyone who tries to get it canceled once its over budget.
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Mar 12, 2015 20:34
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Jonnty posted:Yep - and I don't think there's any developed countries that don't generate some reasonable proportion of their energy from renewable sources. It depends what you mean by "reasonable portion". There are parts of the US where nearly all the electricity comes from coal.  dupersaurus posted:How long does it take for efficiency improvements to trickle down to the population at large? People buying new cars now are getting the deal, but it's all of the used not-so-efficient cars that hold the share, right? Efficiency improvements are great, but I suspect that the energy saved by waiting longer to replace old cars is on par or exceeds the savings from greater efficiency in newer ones. It certainly works out that way economically -- a huge part of the lifetime cost of a car is the car itself, not the fuel it runs on, and I strongly suspect that this goes into the representing the energy (and pollution) costs of production. But I'd love to see someone actually do a proper energy use analysis on this. Again, though, as you say, maybe you don't care, because most of that pollution is happening in China, away from your population.
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Mar 12, 2015 21:06
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Baronjutter posted:Obviously there's no magic bullet, but in North America if anything could be changed in this whole process to make things cheaper, what would be the top changes? My city (St. Louis) took a reasonably innovative stab at the best way to prevent massive cost overruns on a large project (I-64 / I-170 reconstruction). Instead of asking companies to bid on x-specific interstate and interchange rebuild, they asked companies, "With these parameters, how much can you do for $535 million?" The project resulted in some innovative proposals, some of which the city planners hadn't thought of themselves. The project ended up under budget and ahead of schedule. With a bit of the "extra" money they resurfaced some more of the interstate than they originally planned, yay. Wish more projects could follow suit. (coming out of the woodwork - I'm a civil engineer turned household engineer <mom> who worked on this ^ project fresh out of college)
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Mar 13, 2015 04:28
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Lead out in cuffs posted:It depends what you mean by "reasonable portion". There are parts of the US where nearly all the electricity comes from coal. Doesn't really matter though. Even the worst half-legally operated coal plant left in the US pollutes less for the power it pumps out to run a car than the car's internal combustion engine is likely to. West Virginia uses the most coal, 95%, and even they have 1.9% hydroelectric and 2.4% wind/solar/geothermal.
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Mar 13, 2015 05:51
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Roadie posted:Take all the people who decide that the lowest bid should always win the contract and dropkick them out the window. There is nothing wrong with lowest price as the only criteria which decides who gets the contract. As long as it's not on the big projects.
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Mar 13, 2015 13:49
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Nintendo Kid posted:Doesn't really matter though. Even the worst half-legally operated coal plant left in the US pollutes less for the power it pumps out to run a car than the car's internal combustion engine is likely to. I started this post thinking I was going to back up this point with some numbers, but assuming I didn't make any stupid mistakes it doesn't look like this is true, at least as far as CO2 goes. The US Energy Information Administration claims that a coal plant puts out somewhere in the low two pound range (2.0x-2.1x) of CO2 per kilowatt hour of power generated. Since the rest of the data I'm able to easily find is in metric, let's just round that over to 1 kilogram (2.204 lbs) per kilowatt hour which will apparently be a bit worse than average. A Tesla Model S with the 85kWh battery takes around 100kWh of power from the grid for a full charge according to Tesla Forum posters, so we're looking at 100 kilograms of CO2 generated for that full charge. Tesla claims a range of 310 miles by European standards, so at 498 km I'll just round that to 500 km. That's 200 watt hours per kilometer, for 200 grams of CO2 generated. It's probably even worse than that due to losses in transmission, but that's so variable based on where you are on the grid that I'm just going to ignore it. According to this list, that's in the same range as a BMW 750i, an Audi A8L 4.2, an M3/M4, etc. Even if we go favorable to the coal side by assuming an even 2 pounds of CO2 per kWh and neglecting all charging inefficiencies to say the Tesla only takes 85kWh to get that range. we still get 154 grams of CO2 per kilometer which is right there alongside the bigger turbo fours and a few six cylinder cars. At least for CO2 it seems that modern turbocharged and direct injected gasoline cars are in the same range as or sometimes better than the only EV that's a true competitor. Move the EV over to natural gas and it drops down to 110g/km in the 100kWh grid power over 500km scenario putting it in the same class as small diesel cars and sub-1.5l gasoline models. Again this is only looking at CO2, of course there are plenty of other bad things in both gasoline and coal exhaust, but between the particulate matter and minor radioactivity I don't think coal is going to win on whatever's left. tl;dr: CO2 emissions are pretty similar between a gasoline car and a coal-powered Tesla. Hulebr00670065006e posted:There is nothing wrong with lowest price as the only criteria which decides who gets the contract. As long as it's not on the big projects. Anywhere there's an opportunity for "creative" interpretation of the spec the lowest price wins logic can gently caress you.
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Mar 13, 2015 19:16
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Also isn't the production of electric vehicles worse for the environment than conventional? Like batteries are some of the worst things we mass produce.
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Mar 13, 2015 20:30
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Makes me wonder if any of those numbers account for the actual extraction/refinement/transportation of the gasoline. Or for that matter for extraction / transportation of the coal to the plant. I know coal is durty as hell but internally combusting liquid fossil fuels is just poo poo for efficiency, granted we've made some pretty big MPG improvements in the last 15 years.
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Mar 13, 2015 21:21
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wolrah posted:[well-researched analysis] You are awesome. Thank-you for doing the legwork on this. whitey delenda est posted:Makes me wonder if any of those numbers account for the actual extraction/refinement/transportation of the gasoline. Or for that matter for extraction / transportation of the coal to the plant. I know coal is durty as hell but internally combusting liquid fossil fuels is just poo poo for efficiency, granted we've made some pretty big MPG improvements in the last 15 years. Or transmission losses of the electricity in the grid. Full-lifecycle energy and pollution analysis is something I would really, really like to see more research going into, and an area where I hope "big data" can make a difference.
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Mar 13, 2015 22:10
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Baronjutter posted:Also isn't the production of electric vehicles worse for the environment than conventional? Like batteries are some of the worst things we mass produce. Yeah, lithium batteries are pretty bad. Basically everything else about electric cars is the same and occasionally it's better, but as far as I'm aware any batteries with useful energy densities are made of things that aren't exactly pleasant. edit: I really thought Tesla used lithium batteries, apparently they use some kind of nickel/cobalt/aluminum chemistry. Probably still not the greatest things to produce. It is a trade off though, I don't have enough information to judge how that compares to the fossil fuel side of things which obviously aren't winning any environmental awards. whitey delenda est posted:Makes me wonder if any of those numbers account for the actual extraction/refinement/transportation of the gasoline. Or for that matter for extraction / transportation of the coal to the plant. I know coal is durty as hell but internally combusting liquid fossil fuels is just poo poo for efficiency, granted we've made some pretty big MPG improvements in the last 15 years. Most certainly not on either side, and you're right that both internal combustion and coal generation have made pretty notable gains in recent years. Like I said I was surprised at the results, I'm a nuclear fan as far as base load goes but I was willing to accept that simply as a matter of the massive difference in scale a coal plant could run cleaner by proportion than an automotive engine even while using a dirtier fuel. To find that by a major metric coal is so bad that it can make a modern electric car have the same effective CO2 output as a normal car blew my mind. Or maybe it's that modern cars are so drat good at it, either way. wolrah fucked around with this message at 22:48 on Mar 13, 2015 |
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Mar 13, 2015 22:31
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wolrah posted:Most certainly not on either side, and you're right that both internal combustion and coal generation have made pretty notable gains in recent years. Like I said I was surprised at the results, I'm a nuclear fan as far as base load goes but I was willing to accept that simply as a matter of the massive difference in scale a coal plant could run cleaner by proportion than an automotive engine even while using a dirtier fuel. To find that by a major metric coal is so bad that it can make a modern electric car have the same effective CO2 output as a normal car blew my mind. Or maybe it's that modern cars are so drat good at it, either way. Internal combustion engines are really drat efficient for what they do. They've been fine tuned for decades, and now turbos are squeezing even more efficiency out of them. It would be hard to beat that with your typical coal turbine + transmission losses. Also keep in mind that coal plants don't give a poo poo how much CO2 they put out; they just want to do their job cheaply so they can grab a big profit.
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Mar 14, 2015 00:20
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I think the big plus for electric cars is that they shift the pollution from millions of point sources to a few sources (the battery factories). Potentially massive improvements in air quality in cities, and there are several other benefits to electric vehicles. For example, the fact that fossil fuel prices are only ever going to keep going up in the long term.
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Mar 14, 2015 00:23
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Baronjutter posted:Also isn't the production of electric vehicles worse for the environment than conventional? Like batteries are some of the worst things we mass produce. I'm not sure if this is still the car, but early Prius batteries were built with minerals mined in Canada and refined in Europe. The batteries themselves were built in China, the car assembled in Japan, then shipped across the ocean back to North America. Not exactly efficient. At the moment, the best solution in terms of fueling a vehicle (without considering energy for production) is a Tesla in a solar panel covered garage. Tesla's own Supercharger charging stations are solar powered.
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Mar 14, 2015 16:13
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