THE FIELD OF VISION REQUIRED FOR THE SAFE OPERATION OF ANY TYPE OF
MOTORIZED UNIT
Surrounding every vehicle is a circle of 360 degrees of area that
could be affected by the vehicle when it is working or moving. This view requirement can be depicted
graphically as follows:
Any part of the 360 degrees that cannot be viewed by the operator is
referred to in various ways;
“Blind Spots” “Blind Areas” “No Zone Areas” to coin the phrase
created by the Federal Motor Carriers Administration. Some government agencies such as NIOSH do
not name the area but instead define the problem it creates as follows: the blind spot creates a “proximity detection
problem”. All these definitions mean one
simple thing: a person or object in that area cannot be seen or detected by the
driver of the unit when the vehicle is moving.
Blind spots along the side of the tractor-trailer combination or no-zones
can be illustrated by the attached photo.
The operator, safety director or other person responsible has
only 3 tools to cope with blind spots and they are:
The operator’s direct and peripheral
vision
The
exterior mirror system used on the vehicle
Electronic equipment such as cameras and other detection
devices.
For our purposes we assume that of the 360 degrees of required view
the operator will provide a view of 180 degrees direct vision and 60 degrees of
peripheral vision, which is available to help solve the problem if the
configuration of the vehicle itself does not make it impossible to fully use
these faculties.
The combination of the exterior mirror systems and electronic aides
are left to solve the problem of the remaining unseen area. To understand contemporary thinking about the
relationship of these two items towards solution of the problem requires an
understanding of what has transpired in the market-place. In the United States mirror manufacturers
simply have not introduced new mirror technology into the equation and instead
have simply re-packaged old technology into prettier and more costly
packages. The old technology did not do
the job and still does not do the job no matter how pretty the package is or
what it costs. This fact has led most
operators and government agencies into a mind-set that believes what they are
getting now from the manufacturers is all there is so they must look to
electronic solutions to the problem. At
M-C North America Inc. we have determined that such a thought process is wrong
and with our new spot mirror technology are showing operators every day who will
maintain an open mind that they are not bound to look solely to electronic
equipment to solve their problem. In fact, we maintain that the only area on
some vehicles that cannot be shown by the exterior mirror system are the
immediate back of the unit and this may be the only area where the operator will
have to rely upon electronic equipment.
ANALYZING THE PROBLEM OF BLIND SPOTS USING AS AN ILLUSTRATION THE
TYPICAL TRACTOR-TRAILER COMBINATION
Every operator, no matter what type of vehicle is concerned,
understands and is made painfully aware of a simple problem they have with their
working equipment. They want their
equipment to function safely in whatever circumstances it is operating in. If it is a road vehicle they know that the
roadways are getting more and more congested everyday and all the costs
associated even with a minor accident continue to sky-rocket. Insurance costs go up and there is ultimately
an effect on the bottom-line of the income statement of the operation. A sound accident prevention program can
greatly aid here as long as the operator remembers that in addition to thorough
training part of program has to include giving the operator the tools necessary
to put that training into practice. These same problems exist if the units are
off-road vehicles such as construction equipment. Jobs have time limits and a great deal of
machinery moving around the job site and other employees are usually working at
or near the equipment being operated.
An analysis of the typical tractor-trailer combination can provide an
outline to discuss problems with all equipment.
Factors to be considered:
Government regulations and mandates as to exterior
mirrors.
A common observation
observed and expressed by many operators is that they understand there are
Federal Motor Vehicle Safety Standards (FMVSS) developed by the National Highway
Traffic Safety Administration (NHTSA) and that there is a FMVSS 111 that
regulates the mirrors on vehicles that travel the roadways. The reality of this regulation is that it
only applies to the manufacturer of the vehicle at the time the vehicle is
delivered to the buyer. Once the owner takes delivery of the vehicle they are
not bound by the standard. Further, the regulation is deemed by NHTSA to only
state “minimum requirements” and the owner is allowed to exceed these
requirements if they want to. And
finally, what are the manufacturer requirements for trucks provided by FMVSS
111: if the truck has a gross vehicle
weight of 10,000 pounds or more the manufacturer is required to provide a 7 x 7
inch flat glass (called a “unit of magnification” mirror) on each side of the
vehicle before it is delivered to the buyer.
There are no requirements in the Standard for supplementary mirrors on
these types of vehicles. If the vehicle
or unit happens to be an off-road vehicle such as a front-end loader or mine
truck there are no requirements for mirrors under current government
regulations.
The operator of the
tractor-trailer combination clearly understand that the flat glass or “unit of
magnification” mirror provides a field of view for the operator totally
determined by the size of the mirror and that out of the coverage of the
required 360 degrees of view necessary this type of mirror will only provide
some 5-10 degrees. The operator recognizes that this will help the operator in
backing the unit, because it will give the driver an accurate perception of the
area where the vehicle is being backed but will be of no aid to operator on the
road when lane changes and turning maneuvers have to be made. A mirror that will provide additional view,
or a supplementary mirror becomes a necessity.
Role of the truck manufacturer in the mirroring process
The truck manufacturer
has stepped into this need of the operator to expand mirror coverage on the
units and typically offers choices at the time the truck is being
purchased. How much does this fact
contribute to the efforts of the operator to get mirrors that work? Not much, appears to be the answer. Truck
manufacturers have not historically spent a great deal of time understanding the
function of the mirrors they are placing on their trucks. They buy what
generally looks good on their unit and really do not look into how much good the
mirrors do for the operator. Most of
them also offer many types of options as to mirror possibilities but they do not
have any idea what the option offered accomplishes. The operator is left with the final
determination. The questions then
becomes do they buy because the mirror looks good on the vehicle, or do they buy
this because we have always bought this or do they buy with some knowledge of
what they want the mirrors to accomplish.
Inherent problems with configuration of the tractor-trailer
combination that contribute to mirroring problems
In the United States the preference for trucks of all types with
hoods and engine out in front of where the operator sits (as opposed to the trucks that are called
cab-over) where the operator sits right at the front of the vehicle provides the best example of how little
thought has been given to what mirror should do for the operator. The exterior mirrors on all these vehicles
are placed by the manufacturers on the door- frame on each side. This places the
mirrors some 10-15 feet from the front end of the truck. Mirrors cannot show the
operator behind the mirrors so this area becomes a blind area to operator unless
the operator can physically see the area and with the larger and larger size of
trucks being built this means the operator is actually required to stand up in
the seat and look into the area before venturing into that area. A feat not easily accomplished in heavy
traffic conditions.
This blind area is illustrated by the attached
photo;
One Ms. Barbara Sanford actually found her and her car in this area
when a big truck changed lanes and the driver did not stand up to look so she
was involved in an accident and in Federal Docket No. NHSTA-2002-12347 asked the
National Highway Traffic Safety Administration to require that big trucks have a
supplementary mirror placed on the front fender to prevent this type of
accident. Petition denied by the
Administration on grounds that further research was necessary. Thankfully, a large part of the trucking
industry recognizes the common sense of the need for this type of mirror
situation and are voluntarily equipping their fleets with fender mounted mirrors
on both sides of the tractor.
Placing the mirrors on the door frame provides a horizontal plane
field of view of about 30-40 degrees as illustrated by above photo's and
leaves a blind spot regarding other lanes that cause problems in lane changes
and turning maneuvers
Once the decision has been reached as to
the proper location of the spot mirror on the front fender, the selection of the
proper spot mirror to do the job is required.
When we developed our spot mirror technology we considered the most often
used spot mirror the 8 inch round convex that has become the mirror of choice
for front fender mounts. We examined
where this type of technology could be improved and concluded that there were 3
major areas where performance could be improved.
Field of view
The field of view provided by the round convex supplemental mirror is
a cone shape starting from the location of the mirror traveling to a spot where
the ground first becomes visible to the operator. Spot mirrors located on the front fenders are
usually about 6 feet from the ground level.
We also found that the location where the operator first sees the ground
is 40 to 50 feet from the mirrors location.
This means that a blind area along the immediate side of the unit is left
unseen by the operator for persons or objects very close to the side of the
truck. For, instance a Ford Taurus is approximately 4 foot 6 inches from roof
line to ground level. A car could be in
this area at the time a turn or lane change is made. We believe the solution lies in changing the
configuration of the mirror and we have chosen an 8 x 8 inch square model
mirror. This configuration shows the
ground starting at the location of the mirror on the truck and eliminates the
cone triangular shaped blind spot left by the round convex mirror. This mirror
configuration will also provide a view to the side of the truck of the 2
adjoining lanes, more than adequate for turning and lane change
maneuvers.
Glare
Since fender mounted mirrors are located to the front of the driver
glare from bright lights of other vehicles or the sun could directly reflect
into the operator’s eyes. Our solution
was to go to anti-glare glass in our spot mirrors and to provide a glass that
prevents blinding and at the same time will lighten when daylight decreases so
the driver gets a maximum view no matter what light conditions are
present.
Distortion
The most critical area that operators have had to contend with in
using the standard convex mirror as a supplemental mirror is the distortion in
images shown which preclude the driver from correctly assessing where that
person or object is in relation to the driver to make decisions such as it safe
to change lanes. Distortion is one of
the major factors that NHSTA has used consistently for over the past 30 years in
refusing to endorse or require spot mirrors for trucks under the Federal Motor
Vehicle Safety Standards. NHTSA states
the problem in NHSTA Docket No. 2002-12347 as follows:
“The main difference
between a flat mirror and a convex mirror is that the image of an object viewed
is both distorted and smaller that that of the same object viewed in a flat
mirror. Therefore, such an object appears farther away and could be less
recognizable when viewed in a convex mirror.
Additionally, if the object were approaching or receding, its rate of
change in position relative to other vehicles and its speed are more difficult
to judge as well.”
Here the simple fact is that anytime glass is bent, as it is with the
convex mirror, the images produced will be changed from the original. Our goal was to minimize the effect of the
change on the driver’s perception. We
have accomplished this with the M-C (Multi-Camber) spot mirror glass. Unfortunately, words alone cannot convey this
message and the technology must be seen to be
appreciated.
We offer spot mirror technology that provides a required view of the
area along the sides of the truck and a view that provides images that can be
used by the driver in making judgments and welcome the chance to show
you.
Don’t forget to review our Blind-spots illustrated section to
examples of various types of vehicles and how
well manufacturers are doing in providing the view necessary to safely
operate the equipment and our Product section where we will be adding new mirror
systems as they are developed.
Richard T. Ince
Safety Director
M-C North America Inc.