#31
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Is the discussion "there should be separate
lines for bicycles"? It a great idea and here we have countless of km of those, including in urban areas, but surely the ambition isn't a complete separation? That would be out of the question he I ride my bike 3-4 times a day and ~5% of the time on special lines, the rest is among the cars like everyone else. Here, most accidents that involve a bike AND a car, 75-80% of those happen at intersections when the bike rider expects (?) the car to stop, but it doesn't. [1] [1] According to Irene Isaksson-Hellman, traffic analyzer at If, an insurance company. -- underground experts united http://user.it.uu.se/~embe8573 |
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#32
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On 3/13/2018 12:58 PM, Emanuel Berg wrote:
Is the discussion "there should be separate lines for bicycles"? It a great idea and here we have countless of km of those, including in urban areas, but surely the ambition isn't a complete separation? That would be out of the question he I ride my bike 3-4 times a day and ~5% of the time on special lines, the rest is among the cars like everyone else. Here, most accidents that involve a bike AND a car, 75-80% of those happen at intersections when the bike rider expects (?) the car to stop, but it doesn't. [1] [1] According to Irene Isaksson-Hellman, traffic analyzer at If, an insurance company. Forester and others have demonstrated that the bulk of car-bike crashes do happen at intersections. (And that every driveway is in fact an intersection.) They've demonstrated that completely separated bike facilities cannot be separated at intersections, where most crashes happen. And they've pointed out that there can never be a complete separate system getting cyclists to every point, so cyclists must learn to ride with motor vehicle traffic anyway. That doesn't matter. There are still lots of nut cases saying only barrier-separated bike lanes and completely separate trails can be safe. At this point in time, there are fewer than 250 miles barrier-separated bike lanes in America. There are roughly 4 million miles of roads. I guess they never plan to ride on 99.99% of the roads. -- - Frank Krygowski |
#33
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Frank Krygowski wrote:
They've demonstrated that completely separated bike facilities cannot be separated at intersections, where most crashes happen. And they've pointed out that there can never be a complete separate system getting cyclists to every point In theory - why not? In practise - difficult In reality - won't happen as car drivers and shopkeeper won't accept it as aggressivity/stress/frustration would be reduced so much people wouldn't have to buy meaningless things all the time (or drive to Yoga class) -- underground experts united http://user.it.uu.se/~embe8573 |
#34
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On Tuesday, March 13, 2018 at 11:25:36 PM UTC-4, Emanuel Berg wrote:
Frank Krygowski wrote: They've demonstrated that completely separated bike facilities cannot be separated at intersections, where most crashes happen. And they've pointed out that there can never be a complete separate system getting cyclists to every point In theory - why not? In practise - difficult In reality - won't happen as car drivers and shopkeeper won't accept it as aggressivity/stress/frustration would be reduced so much people wouldn't have to buy meaningless things all the time (or drive to Yoga class) "In theory, there's no difference between theory and practice. In practice, there is." The reason it's impossible to build a complete separate system is not just selfishness by motorists and shopkeepers. There are many issues that should be obvious: Expense; Property rights, as related to right-of-way acquisition; Road geometry; Politics; Ineffectiveness; Emergency vehicle response; Maintenance... - Frank Krygowski |
#35
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Frank Krygowski wrote:
The book _Bicycles & Tricycles, An Elementary Treatise_ is probably interesting only to those who love the history of engineering. It was written well over 100 years ago. I enjoyed finding out what they knew back then - which was quite a lot Well, how fast were the fastest cars in the early 20th century? 130 km/h? I mean, wasn't this the Jules Verne, ballon-to-the-north-pole, Titanic, pre-WW1 hay days of this kind'a stuff? -- underground experts united http://user.it.uu.se/~embe8573 |
#36
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On Tuesday, March 13, 2018 at 8:25:36 PM UTC-7, Emanuel Berg wrote:
Frank Krygowski wrote: They've demonstrated that completely separated bike facilities cannot be separated at intersections, where most crashes happen. And they've pointed out that there can never be a complete separate system getting cyclists to every point In theory - why not? In practise - difficult In reality - won't happen as car drivers and shopkeeper won't accept it as aggressivity/stress/frustration would be reduced so much people wouldn't have to buy meaningless things all the time (or drive to Yoga class) I find bicycle traffic stressful. Morning traffic in Portland -- https://i.pinimg.com/736x/2c/bf/90/2...the-bridge.jpg In reality, though, bike traffic in multi-use facilities can be very stressful and equally stressful as driving in a car -- if not more so. https://c2.staticflickr.com/4/3147/2...4b6_z.jpg?zz=1 -- Jay Beattie. |
#37
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jbeattie wrote:
In reality, though, bike traffic in multi-use facilities can be very stressful and equally stressful as driving in a car -- if not more so. People who ride bikes are not stressed. Outdoor, movement, speed, fun, no jams: can't fail. OTOH people who voluntarily lock themself into small boxes where they can yell silently at other people who do exactly the same... My favorite is when a car driver gets out of the car and is angry at everyone and everything. People ask what's the matter and he says, the wheel door still open, that traffic was just horrible. -- underground experts united http://user.it.uu.se/~embe8573 |
#38
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On 3/14/2018 1:42 AM, Emanuel Berg wrote:
Frank Krygowski wrote: The book _Bicycles & Tricycles, An Elementary Treatise_ is probably interesting only to those who love the history of engineering. It was written well over 100 years ago. I enjoyed finding out what they knew back then - which was quite a lot Well, how fast were the fastest cars in the early 20th century? 130 km/h? I mean, wasn't this the Jules Verne, ballon-to-the-north-pole, Titanic, pre-WW1 hay days of this kind'a stuff? You seem to misunderstand what the book's about. I very much doubt there's a single mention of an automobile. The book was written in 1896, in the midst of the first great bike boom, triggered by the combination of the "safety bicycle" chain drive system plus the pneumatic tire. At that time, bikes were the height of technological fashion, kind of like smartphones today. But they were being produced by hundreds and hundreds of companies, and many details of design were not yet understood. There was a lot of craziness in some of the approaches, a lot of ignorant trial and error, a lot of "myth and lore" as Jobst Brandt used to say here. Archibald Sharp was an engineer. Supposedly he had a crusty personality, he engaged in public correspondence in which he pointed out the folly of various designers, and he ultimately wrote this engineering book about bicycles, hoping that people would learn from it and the art would thereby advance. Seems to me he was quite similar to the late Jobst Brandt or Sheldon Brown. The book really is an engineering textbook. It's full of free body diagrams, stress calculations, mathematics of all kinds, illustrations of countless designs, etc. It contains no science fiction. It's all about understanding and applying bicycle physics and engineering. -- - Frank Krygowski |
#39
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SF Topology: was: rim notation
On Tue, 13 Mar 2018 21:07:19 -0700 (PDT), Frank Krygowski
wrote: The reason it's impossible to build a complete separate system is not just selfishness by motorists and shopkeepers. There are many issues that should be obvious: Expense; Property rights, as related to right-of-way acquisition; Road geometry; Politics; Ineffectiveness; Emergency vehicle response; Maintenance... speaking of geometry: Anne McCaffrey's Pern includes a caste of messengers who have built a network of moss-paved footpaths that connect every Hold and Weyr. These same points are also connected by dirt paths beaten by travellers on horseback. (Pardon me, "runner-beast"back.) A messenger running from point A to point B never, ever crosses a horse trail connecting point C to point D. Not so much as a cowpath! Please draw me a map of how this works. In "Imperial Earth", Arthur C. Clarke manages better: Since cars are self-driving, roads are no wider than railroad tracks, and there is only one lane in each direction. Intersections with other roads aren't mentioned, but while being driven to his host's home, the protagonist passes under an overpass carrying a much wider road. The host explains to him that bicycles require more room because humans are steering them. -- Joy Beeson joy beeson at comcast dot net http://wlweather.net/PAGEJOY/ |
#40
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SF Topology: was: rim notation
On 3/16/2018 12:50 AM, Joy Beeson wrote:
On Tue, 13 Mar 2018 21:07:19 -0700 (PDT), Frank Krygowski wrote: The reason it's impossible to build a complete separate system is not just selfishness by motorists and shopkeepers. There are many issues that should be obvious: Expense; Property rights, as related to right-of-way acquisition; Road geometry; Politics; Ineffectiveness; Emergency vehicle response; Maintenance... speaking of geometry: Anne McCaffrey's Pern includes a caste of messengers who have built a network of moss-paved footpaths that connect every Hold and Weyr. These same points are also connected by dirt paths beaten by travellers on horseback. (Pardon me, "runner-beast"back.) A messenger running from point A to point B never, ever crosses a horse trail connecting point C to point D. Not so much as a cowpath! Please draw me a map of how this works. For fans of McCaffrey, the obvious answer is that at the intersections, one path "goes between." ;-) But more seriously: I doubt any of the segregation proponents will accept your challenge to draw the map. In "Imperial Earth", Arthur C. Clarke manages better: Since cars are self-driving, roads are no wider than railroad tracks, and there is only one lane in each direction. Intersections with other roads aren't mentioned, but while being driven to his host's home, the protagonist passes under an overpass carrying a much wider road. The host explains to him that bicycles require more room because humans are steering them. That's slightly more realistic. Back to the first point: Way, way back in time, I was a member of a committee charged with finding a way to connect our village to a riverside MUP about 7 miles away. We started with the assumption that the MUP could be extended closer along the riverside, which in itself would be a difficult, decade-long project. So we concentrated on finding a route up the side of the river valley. Briefly, there was no way. Terrain, commercial property, roadways, freeways, private property, etc. showed it was just impossible. Besides, there were relatively low-traffic roads that were fine for any minimally competent cyclist. All that meant it was silly to even try. There were times that same committee, with slightly different objectives, looked longingly at power line rights of way or gas line rights of way. I suppose in some ideal society, one might be able to get a MUP along those. But they (especially the gas lines) tended to be nowhere-to-nowhere lines. If a gas line ROW got a paved path, I'm sure it would generate some riding; but it would be entirely by the crew that parks the car and rides the bike out and back to the car. -- - Frank Krygowski |
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