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Old February 24th 13, 09:29 AM posted to uk.rec.cycling
Mrcheerful[_3_]
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Posts: 2,662
Default Classifying Pedestrians, Bicycles and Motor Vehicles

Bret Cahill wrote:
It's easy to separate motor vehicles from bicycles and pedestrians
-- just use those spikes like in gated communities. Cyclists can
slip between the spikes or stop and step over them as can
pedestrians. A motor vehicle will get 4 damaged tires.


Separating cyclists from pedestrians is trickier. The first obvious
solution would be to install parallel bars like on cattle stops on
sidewalks/pavements. A good wheelman, however, will just hit these
at an angle like he does oblique railroad tracks. Maybe some
combination of patches of ice and grates would work but that would
be expensive to install and maintain and dangerous to pedestrians
as well.


Moreover the weight of a cyclist + bicycle averages about that of a
pedestrian, both an order of magnitude less massive than a motor
vehicle. Even more compelling a motor vehicle often represents 2
orders of magnitude more kinetic energy.


As a practical matter, is there really any reason not to reclassify
cyclists as pedestrians as far as cycling on the sidewalk/pavement
is concerned?


Bret Cahill


wheeled traffic on the road, foot traffic on the footpath. The main
reason to keep wheeled traffic separate from foot traffic is the
speed differential, which is the same reason that car and bicycle
traffic is incompatible.


The issue is avoiding injuries from collisions. After all, who cares
about a collision where no one gets hurt?

Injuries from collisions comes from 2 major sources:

1. the relative kinetic energies of 2 objects during impacts, and,

2. the crushing weight of one object as it falls or rolls over the
other.

In the first the kinetic energy is often 2 orders of magnitude higher
with a motor vehicle than a bicycle.

In the second the crushing force is an order of magnitude higher with
a motor vehicle than a bicycle.


Bret Cahill


if there were no forces involved then there would be no collision. Any
collision (even the very slightest) with a pedestrian may be sufficient to
kill the pedestrian. Any collision of pedestrian with a wheeled vehicle on
the pavement is unacceptable. Bicycles are the most common wheeled vehicle
making journeys on footpaths.


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