A comparison of energy use per passenger-mile, and a graph of the same with PRT included.
Nothing in these graphs mentions the occupancy rates, which route selection and timetable management would affect a lot. Note that the most efficient mode of transport in BTU's per passenger, behind the "Skyweb" system (and if this information is being published by skyweb, forgive me if I take a bit of a "wait and see" stance on the figures they quote for their system) is... intercity bus!
Urban buses are listed as the the most inefficient, and this would be due to the frequent deceleration and acceleration of the mass of the bus and passengers.
As I said, a bus from a terminal to a carpark does not need to stop along the way, giving it an efficiency close to the "intercity bus" figures in the graphs you quoted.
People can walk to their cars. They're not going to have a lot of luggage (because they have just flown), and surely two or three bus stops in the car park could drop people off reasonably close to their cars, and not cost too much energy. For the disabled, elderly, there are other solutions...
Where does this magical economy of scale come in? There's no economy of scale in physics. Weight costs energy. Stopping costs energy. Big electrical motors aren't particularly more efficient than small motors.
It comes from reduction in "infrastructure" (by which I mean the weight of the vehicles components) per passenger. A bus that carries ten times the number of people as a car does not have to be ten times as heavy or have an engine ten times as large as a car. It does not have to consume ten times the energy to move ten times the passengers, because the weight of the passengers is only a small paprt of the weight of a vehicle.
You also get savings in drag. Unless ten cars can travel within a few feet of each other to get the maximum benefits of the preceding cars slip stream, then the total drag-resistance that the engines have to overcome for all passengers is less in the bus than for the cars. A bus or train only has to punch one hole through the air.
I was not saying that large electric motors are more efficient than small ones. I was just saying that the above-mentioned economies of scale apply equally to combustion-engine-drive or electric-motor-driven vehicles.
This PDF shows rail as about 5x more. I don't know if I trust that PDF, but clearly rail is more expensive. The tolerances are much lower. As for drag, yes, iron-on-iron wheels cause less drag [but the iron manufacturing is expensive].
5 x more in initial costs according to the PDF. When it comes to moving mass from point A to point B, rail is very efficient. Therefore, I think the total cost of ownership would be more favourable.
Like yourself, I don't really trust that PDF anyway. For starters, it contradicts the previous links you gave me which show urban busses as being the most inefficient form of transport in BTU's per passenger. The PDF says urban busses are cheaper per passenger than rail... if it is, it's only because the true costs of energy haven't be realised yet.
There are quite a few other fallacies in that document (eg "trains can only go 55mph, which is slower than a bus, therefore rail is slower". Ignores traffic, number of stops etc. Stupid point), which make me highly suspicious of an agenda and frankly I just don't believe much of what it contains because of that.
and part of what keeps rail from serving many areas without tunneling and other expensive infrastructure that only takes the rail further from people.
I'm not trying to say rail or bus is a silver-bullet solution for all transport problems.
Only with high occupancy, close to 100% full. That only happens during peak periods. During other times the costs and inefficiency of accelerating and decelerating a large heavy and nearly empty vehicle are substantial, never mind the environmental cost of the rail
Close to 100% full? I don't have any figures to dispute this, but somehow I doubt you have any to prove it either. In the example I used above (1 big diesel engine vs lots of little petrol motors), 50% occupation would still have been at least as efficient as having a car for every two passengers
The fact that this example used combustion engines is irrelevant. I could have illistrated the same point with a large electric bus (say, 400kw motor) vs many small electric cars (say, 75kw motors). Energy is energy. The point I'm making as about the economy of scale you get with one big, powerful vehicle that moves many people vs many little vehicles that move a few people each.
You could automate the eletric bus as easily a you could automate each of the cars.
Railways are cheaper to build than roads. And they are a more efficient way of making contact with the ground (narrow wheels), which means less drag.
I'll concede that the "on-demand" nature of having pods ready to go when you are ready to go is more convenient and may save passengers the 5 or 10 minutes they would otherwise have to wait for a bus, but I can't see how anyone can say it's more efficient in terms of energy and maintenance overheads.
I tell you what would be energy efficient - having one bus stop at each car park and getting people to WALK to their cars. The nature of flying means that not many people are going to have a 500kg of luggage to take to a car, although I'm sure the inconvenience would be truly terrible. There could be a few pods for the elderly and disabled that are local to each park, which take them from the bus stop to their cars.
good post... I think the analogy about the pit bull / croc is really insightful... pity I don't have some mod points to give;-)
The comment is old, the story is older, but I just wanted to acknowledge this post.
Cheers
Firstly, vehicles and associated infrastructure to move lots of people in one "hit" may be heavy and more expensive, but transport of this type benefits from the economy of scale and is more energy efficient. It's cheaper to run a single 8-litre, 6 cylinder diesel engine that shifts 50 people than to run 25 x 1.5 litre, 4 cylinder petrol engines to shift the same number (two passengers per car).
Add the overhead of a driver for each vehicle, and you can see it really does make a lot of sense to run busses.
Secondly, in the example quoted (the electric cars at heathrow) the route to the carpark is the same for all passengers, so the problem of not being able to "split up" and take passengers on individual routes does not exist.
The destination is also the same for all passengers, so the problem of stopping every now and then to pick up and set down passengers along the way (and this slow the trip down) doesn't really exist.
well, i think you said it really. You didn't know anything of him aside from the incident with his child at a public crocodile-feeding display.
I used to cringe at the way he came across and the things he did, I just thought he was an idiot. Until I realised that despite all the faults, he really had the best of intentions, and he was a lot more sincere that most of the people you will see on TV. You can't take that away from him. Even though he made tens of millions of dollars with what he did, he just put it into his conservation fund and drew a wage like all of his other employees. He didn't live it up with all of the money he made, he put it all into trying to make the world a better place.
After I realised this, I started to cringe on his behalf instead of at him, I felt sorry for him. But now I know I needn't have bothered. Millions of people loved him and didn't see anything wrong with the way he was. That's more than I can say for myself....
Isn't this hilarious! omg... CRIKEY! I'm DEAD... CRIKEY!! GET IT? LOLLOL
I'm sure I'll be instantly reprimanded, reminded of the place of black humour, and told how much of a wuss I am being. In fact I'm sure there are armies of nerds just waiting to pounce on anyone who is silly enough to object to the clammering for "funny" mod points before the story gets old. Black humour does have it's place, and I did expect there to be a lot here, but when the entire top half of this page is filled with these comments modded "+5 funny", something about it is just a bit disheartening, quite frankly.
So anyway, I'm not sure who won this round of the perpetual/. competition to be the 'uber nerd', to show that you're too cool to care (especially when people might expect you to care), but I would just like to show some 'weakness' and say that I find this part of todays news to be kind of sad.
He could be annoying, embarassing, he courted danger (and eventually paid the price)... but he was so exuberant and positive, and niave in a way. No one can accuse him of being fake or caring about himself more than the environment so many of us neglect as matter of mere convenience. Something about his positive outlook and naive manner in contrast with his early death just seems sad to me. Poor bloke
Like you say, they are very hard to provoke. Many of the posts here describe how this is a mechanical reaction on behalf of the stingray, not a conscious decision to attack. From what I can gather (from a few news articles I've read), he didn't provoke it. He swam over the top of it and triggered the reaction.
From http://www.abc.net.au/news/newsitems/200609/s17326 63.htm
John Stainton says the fatal incident was unprovoked.
He says the wildlife expert and a cameraman were snorkelling across Batt Reef in shallow water at about 11:00 am AEST.
Mr Stainton says the cameraman was initially unaware of the fatal sting.
"He [Irwin] just swum over the top of the ray and the barb came up and hit him," he said.
"The cameraman said at the time he didn't even know that it had hit him [Irwin] and then he saw blood in the water."
...claims that they in no way had anything to do with, or in any way support this kind of sabotage (allegedly), just in case anyone starts saying crazy stuff like that
I wonder (and perhaps someone with more education than I can speculate), if amyloid concetrations in the brain are reduced, will the patients be able to remember things that they have forgotten, or will they "just" be capable of remembering new information again?
They probably also use software that recognises skin tones, which would help prioritise what photos to review. The government department I work in employs such software to monitor email picture attachments and web surfing.
There are workarounds of course, but this is a pretty big net.
... that in the 1800's they probably named the paper "Christian Science Monitor" to try and reconcile some Christians and "blasphemous science", to show that follow science and not give up Christian ideals and beliefs. Now, it probably serves as a bridge in the opposite direction, demonstrating to "rational" people that Christianity doesn't mean giving up science.
Slashdot Mirror
so you're saying you think Mary and her son, Jesus, did exist, then?
to google:
This is what happened to the last company CEO that got in the way of ACCC
there needs to be more than just "5" for comments like that...
Urban buses are listed as the the most inefficient, and this would be due to the frequent deceleration and acceleration of the mass of the bus and passengers.
As I said, a bus from a terminal to a carpark does not need to stop along the way, giving it an efficiency close to the "intercity bus" figures in the graphs you quoted. People can walk to their cars. They're not going to have a lot of luggage (because they have just flown), and surely two or three bus stops in the car park could drop people off reasonably close to their cars, and not cost too much energy. For the disabled, elderly, there are other solutions... It comes from reduction in "infrastructure" (by which I mean the weight of the vehicles components) per passenger. A bus that carries ten times the number of people as a car does not have to be ten times as heavy or have an engine ten times as large as a car. It does not have to consume ten times the energy to move ten times the passengers, because the weight of the passengers is only a small paprt of the weight of a vehicle.
You also get savings in drag. Unless ten cars can travel within a few feet of each other to get the maximum benefits of the preceding cars slip stream, then the total drag-resistance that the engines have to overcome for all passengers is less in the bus than for the cars. A bus or train only has to punch one hole through the air.
I was not saying that large electric motors are more efficient than small ones. I was just saying that the above-mentioned economies of scale apply equally to combustion-engine-drive or electric-motor-driven vehicles. 5 x more in initial costs according to the PDF. When it comes to moving mass from point A to point B, rail is very efficient. Therefore, I think the total cost of ownership would be more favourable.
Like yourself, I don't really trust that PDF anyway. For starters, it contradicts the previous links you gave me which show urban busses as being the most inefficient form of transport in BTU's per passenger. The PDF says urban busses are cheaper per passenger than rail... if it is, it's only because the true costs of energy haven't be realised yet.
There are quite a few other fallacies in that document (eg "trains can only go 55mph, which is slower than a bus, therefore rail is slower". Ignores traffic, number of stops etc. Stupid point), which make me highly suspicious of an agenda and frankly I just don't believe much of what it contains because of that. I'm not trying to say rail or bus is a silver-bullet solution for all transport problems.
The fact that this example used combustion engines is irrelevant. I could have illistrated the same point with a large electric bus (say, 400kw motor) vs many small electric cars (say, 75kw motors). Energy is energy. The point I'm making as about the economy of scale you get with one big, powerful vehicle that moves many people vs many little vehicles that move a few people each.
You could automate the eletric bus as easily a you could automate each of the cars.
Railways are cheaper to build than roads. And they are a more efficient way of making contact with the ground (narrow wheels), which means less drag.
I'll concede that the "on-demand" nature of having pods ready to go when you are ready to go is more convenient and may save passengers the 5 or 10 minutes they would otherwise have to wait for a bus, but I can't see how anyone can say it's more efficient in terms of energy and maintenance overheads.
I tell you what would be energy efficient - having one bus stop at each car park and getting people to WALK to their cars. The nature of flying means that not many people are going to have a 500kg of luggage to take to a car, although I'm sure the inconvenience would be truly terrible. There could be a few pods for the elderly and disabled that are local to each park, which take them from the bus stop to their cars.
good post... I think the analogy about the pit bull / croc is really insightful... pity I don't have some mod points to give ;-)
The comment is old, the story is older, but I just wanted to acknowledge this post. Cheers
Firstly, vehicles and associated infrastructure to move lots of people in one "hit" may be heavy and more expensive, but transport of this type benefits from the economy of scale and is more energy efficient. It's cheaper to run a single 8-litre, 6 cylinder diesel engine that shifts 50 people than to run 25 x 1.5 litre, 4 cylinder petrol engines to shift the same number (two passengers per car).
Add the overhead of a driver for each vehicle, and you can see it really does make a lot of sense to run busses.
Secondly, in the example quoted (the electric cars at heathrow) the route to the carpark is the same for all passengers, so the problem of not being able to "split up" and take passengers on individual routes does not exist.
The destination is also the same for all passengers, so the problem of stopping every now and then to pick up and set down passengers along the way (and this slow the trip down) doesn't really exist.
well, i think you said it really. You didn't know anything of him aside from the incident with his child at a public crocodile-feeding display.
I used to cringe at the way he came across and the things he did, I just thought he was an idiot. Until I realised that despite all the faults, he really had the best of intentions, and he was a lot more sincere that most of the people you will see on TV. You can't take that away from him. Even though he made tens of millions of dollars with what he did, he just put it into his conservation fund and drew a wage like all of his other employees. He didn't live it up with all of the money he made, he put it all into trying to make the world a better place.
After I realised this, I started to cringe on his behalf instead of at him, I felt sorry for him. But now I know I needn't have bothered. Millions of people loved him and didn't see anything wrong with the way he was. That's more than I can say for myself....
Isn't this hilarious! omg... CRIKEY! I'm DEAD... CRIKEY!! GET IT? LOLLOL
/. competition to be the 'uber nerd', to show that you're too cool to care (especially when people might expect you to care), but I would just like to show some 'weakness' and say that I find this part of todays news to be kind of sad.
I'm sure I'll be instantly reprimanded, reminded of the place of black humour, and told how much of a wuss I am being. In fact I'm sure there are armies of nerds just waiting to pounce on anyone who is silly enough to object to the clammering for "funny" mod points before the story gets old. Black humour does have it's place, and I did expect there to be a lot here, but when the entire top half of this page is filled with these comments modded "+5 funny", something about it is just a bit disheartening, quite frankly.
So anyway, I'm not sure who won this round of the perpetual
He could be annoying, embarassing, he courted danger (and eventually paid the price)... but he was so exuberant and positive, and niave in a way. No one can accuse him of being fake or caring about himself more than the environment so many of us neglect as matter of mere convenience. Something about his positive outlook and naive manner in contrast with his early death just seems sad to me. Poor bloke
I think a troll has gotten under your gaurd. Surely we've been had. The whole article is a troll.
Google buys the University of California computer science school
oh, but don't you see?! They will ALWAYS have an "unrelated" reason to arrest someone....
...claims that they in no way had anything to do with, or in any way support this kind of sabotage (allegedly), just in case anyone starts saying crazy stuff like that
LA electricity company CEO given key to city
I wonder (and perhaps someone with more education than I can speculate), if amyloid concetrations in the brain are reduced, will the patients be able to remember things that they have forgotten, or will they "just" be capable of remembering new information again?
They probably also use software that recognises skin tones, which would help prioritise what photos to review. The government department I work in employs such software to monitor email picture attachments and web surfing. There are workarounds of course, but this is a pretty big net.
... that in the 1800's they probably named the paper "Christian Science Monitor" to try and reconcile some Christians and "blasphemous science", to show that follow science and not give up Christian ideals and beliefs. Now, it probably serves as a bridge in the opposite direction, demonstrating to "rational" people that Christianity doesn't mean giving up science.