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  #31  
Old March 13th 18, 05:58 PM posted to rec.bicycles.tech
Emanuel Berg[_2_]
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Posts: 1,035
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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  
Old March 14th 18, 04:06 AM posted to rec.bicycles.tech
Frank Krygowski[_4_]
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Posts: 6,422
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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  
Old March 14th 18, 04:25 AM posted to rec.bicycles.tech
Emanuel Berg[_2_]
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Posts: 1,035
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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  
Old March 14th 18, 05:07 AM posted to rec.bicycles.tech
Frank Krygowski[_2_]
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Posts: 7,077
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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  
Old March 14th 18, 06:42 AM posted to rec.bicycles.tech
Emanuel Berg[_2_]
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Posts: 1,035
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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  
Old March 14th 18, 03:17 PM posted to rec.bicycles.tech
JBeattie
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Posts: 3,495
Default rim notation

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  
Old March 14th 18, 03:58 PM posted to rec.bicycles.tech
Emanuel Berg[_2_]
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Posts: 1,035
Default rim notation

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  
Old March 14th 18, 04:29 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
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Posts: 6,422
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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  
Old March 16th 18, 05:50 AM posted to rec.bicycles.tech
Joy Beeson
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Posts: 1,184
Default 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  
Old March 16th 18, 05:26 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
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Posts: 6,422
Default 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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