"frkrygow" <"frkrygow"@omitcc.ysu.edu> wrote in message news:<
[email protected]>...
> Brent Hugh wrote:
>
> > Just off the top of my head, I can think of three pedestrians that
> > were killed this way in Missouri over the past year or two--two of these young kids killed by
> > school buses.
>
> In our city, we had a kid on a bike killed exactly that way, about two years ago. In that case, it
> was the back wheels of a large truck.
Here's a little more about this type of accident, from a paper by James M. Green on the subject.
Since even my excerpts are rather long, here is the executive summary:
1. The large rotating wheels of buses & large trucks actually create a force that can suck
cyclists/pedestrians right into the wheel (via the Bernoulli principle)
2. There is a simple device, quite new to the market, that counteracts the sucking force, actually
turning it into a slightly repelling force. It also helps with knockdown type accidents with the
large wheels while the buses are turning.
3. The device is highly effective.
4. This is another good reason to keep FAR away from the sides of buses/trucks while riding.
Paper excerpts:
---
Recent risk management efforts at various transit authorities [2] have revealed a prevalent type of
accident from transit vehicles interacting with either cyclists or pedestrians. The predominant
accident type seems to be pedestrians or cyclists being pulled into the bus-wheel, as opposed to
individuals being struck by the vehicle body [3]. Further questioning of transit personnel indicates
that, in most cases, the accidents occur from the rotating bus transit wheel on the bus as it passes
the individual as opposed to the cyclist or pedestrian running into the stationary transit vehicle
or tire. Surprisingly, the type of accident where the bus strikes the cyclist or pedestrian in an
area other than on the rotating wheel is almost negligible.
. . . By whatever analysis method that is used, there is a clear problem with these types of
accidents. Of particular interest is the fact that most points of impact onto the bus body appear
to occur at the point of the rotating wheel in the bus wheel well. . . . More probably than not,
other types of motor vehicles, such as trucks, would also tend to have a high degree of cyclist
or pedestrian accident prevalence at wheel wells. . . .
--
The author gives an argument that a bus passing a cyclist/pedestrian
actually creates a "suction" (via Bernoulli's principle) that is
greatest at the point of the wheel, that tends to pull a cyclist or
pedestrian right into the bus, and preferentially at the wheel.
--
By having a curved wheel guard at the forward leading edge of the
transit bus wheel well, a net outward pressure away from the direction
of travel of the bus is produced. This results in the complete
eliminationof the low-pressure gradient that would draw the cyclist or
pedestrian into the high velocity-rotating wheel. More importantly,
the curvature of the guard would act like an airplane wing and
literally be able to push the cyclist or pedestrian out of the path of
travel of the transit bus.
--
The article gives a diagram of such a guard.
--
. . . field trials do support the ability of this design to
physically move a subject from the path of travel. This is helpful in
instances where Bernoulli's principal is not a causal factor, as when
transit buses turn into pedestrians or cyclists. In those instances,
the guard must act much like the cowcatcher on a train and physically
move the individual from the path of the rotating wheel . . .
[Beside the Bernoulli principle "sucking"] the bus physically turning
into the path of an accident victim should be considered. Of equal
importance in the analysis is the fact that remedial measures are
easily available to prevent these accidents. The illustrated S-1 Gard
(generic name), see Figure 2, has been implemented in several
municipality's. Thus far, in those municipalities that have initiated
this program the accident rate has decreased from several incidents
per year to zero.
--
The paper states that use of these guards is in its "infancy" so
perhaps I was wrong that such guards are already being used in other
countries (though I'm quite certain that I've read that some sort of
guard or shield--perhaps not this exact same sort--is required by law
in some countries, but I can't find the sources where I read that now,
and perhaps they were wrong . . . ).
You can read the full paper, including diagrams and footnotes, in PDF
form at
http://www.bikereconstruction.com/EngineeringPapers/S-1Gard%20Paper.pdf
Or follow this nasty long link for a google cache (HTML):
http://216.239.41.104/search?q=cache
6dqM-dKczoJ:www.bikereconstruction.com/EngineeringPapers/S-1Gard%2520Paper.pdf+%22wheel+guard%22++pedestrian&hl=en&ie=UTF-8
For the benefit of Bob I'll point out in advance that he's right that
this type of shield has no chance of stopping the kind of accident
that started this thread (kid riding out of the driveway straight into
the side of a truck) but I think it's interesting nonetheless.
"Several incidents a year to zero" is pretty impressive for a
(relatively) inexpensive and simple device.
--Brent
bhugh [at] mwsc.edu
www.MoBikeFed.org
