For Your Information

This page is intended to present discussions of topics pertinent to the services we provide, which are of interest to attorneys and insurance claim staff. If there is a particular issue or subject you would like to see covered, please let us know by e-mail to info@foreng.com.

This page was last revised on January 15, 2010

 1. Discussion Forum 
 2. Vehicle refueling safety
 3. Fire awareness savvy
 4. Ground fault circuit interrupters
 5. Safety of walking surface
 6. Factlets about Safe Driving
 7. Vehicle air bags
 8. Formula for a safe staircase
 9. Warnings, cautions and the hierarchy of control
 10. Responsibility among multiple employers
 11. Motor vehicle accident reconstruction
 12. Computer based collision reconstruction programs
 13. Ergonomics
 14. Safety tips and product recalls
 15. NHTSA proposed standards

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Discussion Forum

We invite accident reconstructions to participate in this forum involving the engineering aspects of personal injury and property casualty investigation and analysis. Clicking on the following link for Guest users will bring you to the WebMail Guest Login. E-mailbox name is mshanok@foreng.com. Guest login is Guest, Password is forensic. Once at the site, click on Discussions in the left column.

Guest users, click here.

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Vehicle refueling safety

The Petroleum Equipment Institute's campaign to make people aware of fires which occur as a result of static electricity at gas pumps, while refueling, has ended, but the lessons bear heeding. It is the vapors that come out of the gas that cause the fire, upon contact with a static electricity charge. It is unwise to reenter the vehicle during refueling. As your clothing - especially nylon and other synthetic fabric - brushes against the upholstery, a static charge is built up which can discharge in a spark when you grasp the hose nozzle or touch the vehicle in its immediate proximity. NEVER get back into your vehicle while filling it with gas. If you absolutely HAVE to get in your vehicle while the gas is pumping, make sure you get out, close the door and TOUCH A METAL PART OF THE VEHICLE before you ever pull the nozzle out. This way, the static electricity from your body will be discharged before you even remove the nozzle (because most men don't wear clothing with a large area such as a skirt, and seldom get back in their vehicle until completely finished refueling, they are seldom involved in these types of fires). The stories that claim cell phones are responsible for fires is a myth. However, you shouldn't be distracted or leave the fuel nozzle unattended, so don't ever use cell phones when pumping gas.

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Test your fire awareness savvy
Answers are at the bottom of this page.

1. The most common cause of fatal residential fires is:

a. Malfunctioning furnace or fireplace
b. Candles left burning without supervision
c. Children playing with matches or cigarette lighters
d. Careless smoking or disposal of smoking materials

2. Most residential fires occur when?

a. Late evening, when smokers become tired or careless
b. Over night while occupants are sleeping
c. During absences, with electrical appliances left running
d. During meal preparation

3. The most common cause of electrical residential fires is:

a. Flammable materials left in the vicinity of a baseboard heater
b. Too many appliances plugged into one outlet
c. Damaged or overloaded extension cords
d. Heat from halogen light torcheres

4. How effective are smoke detectors in improving the likelihood of residential fire survival?

a. 30% better
b. 50% better
c. 80% better
d. 100% better

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NESF and CPSC URGE CONSUMERS TO "TEST AND PROTECT"


The Electrical Safety Foundation International (ESFI) and the U.S. Consumer Product Safety Commission (CPSC) together urge consumers to be aware of ground fault circuit interrupters (GFCIs) - the "TEST" and "RESET" buttons on outlets in bathrooms, kitchens and circuit panel in their homes - and to test them monthly and after every major electrical storm. To get the message out, as part of Electrical Safety InternationalMonth in May, the NESF recently launched the "Test and Protect" GFCI Awareness media campaign, sending print and video news releases to media across the country.

More than 400 million GFCIs, which prevent serious electrical shock or electrocution by shutting off power in a circuit if they detect leakage of electrical current, have been installed in homes across the country since the early 1970s. However, a recent industry study showed that roughly 10 percent may be damaged under common circumstances including power surges due to electrical storms.

Ground faults occur when the electrical current in an electrical appliance or other product stays outside the path where it should normally flow. If a person provides a path for the live current to the ground, he or she may be severely shocked or even electrocuted. GFCIs, detecting even a minimal difference between electricity flowing out of and returning to the device, act quickly to intercede and shut off the flow of electrical current through the circuit (and a person) helping to prevent injury or death.

The GFCI test is simple.  Simply plug a nightlight into a GFCI outlet and turn it on. Press the "TEST" button; the light should go off. Press the "RESET" button; the light should go back on. If the light does not go out when the "TEST" button is pressed, you should contact a qualified electrician to correct the problem.

For more information on GFCIs and electrical safety in the home, school, and workplace, the ESFI website, www.esfi.org, features an interactive GFCI demo and educational material.  Interested parties can also request more information by e-mail at info@esfi.org, by phone at 703-841-3229, by fax at 703-841-3329, or by mail by sending a self-addressed, stamped (60-cent) envelope to:

Electrical Safety Foundation International
1300 N. 17th Street, Suite 1847
Rosslyn, VA   22209

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Analyzing the Safety of a Walking Surface


When safety engineers talk about the safety of a walking surface, they usually refer to a property called the coefficient of friction. This is a seemingly simple yet deceptively complex and often misunderstood term. The following is a brief introduction to the subject.

Fundamentally, the coefficient of friction is merely a nondimensional measure of the traction of a surface. It is derived by dividing the weight of an object by the horizontally exerted force required to push the object across the surface in question. As an example, if it takes 6 pounds of force, exerted horizontally, to move a ten pound object across the floor, the floor's coefficient of friction is 6 divided by 10, or 0.6.

Now for a bit of complication. Isaac Newton first propounded that an object at rest has a tendency to remain at rest, unless a force is induced to place it in motion. If that is correct (and, believe me, it is), then we have to add a little bit of extra force to start moving a stopped object across the surface. Once it starts to move, less force is necessary to keep it moving. The term commonly used to quantify the force ratio necessary to initiate the object's slide is the static coefficient of friction. The term used to quantify the force ratio necessary to keep the object sliding is the dynamic coefficient of friction. As an example, if it takes 7 pounds of force necessary to start a ten pound object's slide across a surface and 6 pounds to maintain its slide, then the static coefficient of friction is .7 and the dynamic coefficient of friction is .6.

Safety engineers have universally accepted a static coefficient of friction of 0.5 or greater as the indicator of a safe walking surface's measure of safe traction. As the static coefficient of friction becomes lower, the surface is more slippery and therefore, less safe. Carpeted surfaces usually have a static coefficient of friction in the order of 0.8 to slightly greater than one. Waxed and polished floors can have a static coefficient of friction of 0.3. An icy surface can have a static coefficient of friction of 0.2.

The nonscientific term generally used to characterize the difference between the static and dynamic coefficient of friction is stiction. Every surface has a slightly different amount of this property. The most dangerously slippery surfaces are those which have a very low static coefficient of friction and a large difference between the static and dynamic coefficient of friction.

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Cell Phones and Diving Safety

The National Safety Council has published a bulletin stating that its statisticians have completed a study resulting in an estimate that a minimum of 28% of all motor vehicle crashes in 2008 were attributable to cell phone use and texting, accounting for more than 1.6 million crashes. NSC acknowledges that, although texting while driving is a riskier behavior, cell phone use while driving causes more crashes because more drivers use cell phones than do texting while driving.


How well do air bags work?

For many years, motorists have been under the general assumption that a driver will almost always be able to walk (or be extracted ) out of a bad crash virtually unscathed, provided the vehicle was equipped with an air bag. This is not so. Here are some facts which refute a number of common misconceptions:

Air bags only significantly lessen injury if the occupant is wearing a seat belt. In fact, repetitive studies of actual crashes (not staged crashes using instrumented dummies) have always demonstrated that crash injuries to unbelted occupants in seats protected by deployed air bags, are not much different than would have occurred, had the air bag not been present at all.

Even when seat belts are used, air bags are, by no means, ultimate protection under all circumstances. Most importantly, they will only deploy when the vehicle experiences substantial forward motion deceleration, equivalent to striking a brick wall head-on at a speed of at least 10-15 miles per hour or a similar sized vehicle head-on at 20-30 mph. Although the incidence of fatality is reduced by almost 100% at lower speeds, at highway speeds, that number is reduced to an average 31% of purely frontal crashes, 19% for all relatively frontal crashes and only 11% for all crashes.

For vehicles with frontal damage, an air bag in combination with manual lap-shoulder belts, provides the greatest protection against moderate injury. The chance of moderate injury for that combination, is approximately 61%, about the same in frontal crashes as in all crashes. In comparison, the effectiveness of the air bag alone, in frontal crashes, was 6% - much lower than in all crashes. In fact, data suggests that air bag deployment in which belts are not used, may result in increased risk of moderate injury in some situations.

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The formula for a safe staircase


Stairways have been in existence since humans were first able to fashion the tools to make them. However, the earliest staircases which remain to be examined are, for the most part, very crude, steep and uneven. It was not until the seventeenth century that stairway geometry became consistent, throughout Europe. The first known formula for a safe staircase was developed by Vitruvious, in the first century, B.C. However, there was no standardized formula for staircase geometry based upon natural human gait until 1675, when Francois Blondell, then director of the French Royal Academy of Architects, decided that a proper stair should have twice the riser height plus the tread width equal to a distance between 24 and 25 inches (the "royal inch" of that time was a touch larger than the inch of today). This rule was universally adopted by most designers and was carried into the modern building codes (with slight change to reflect the taller stature of people in these ages), until the early 1980's, when advanced ergonomic studies revealed the need for more complex requirements.

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Warnings, Cautions and the Hierarchy of Controls

There is a very formal and well recognized system for evaluating the steps which can be taken to protect against hazards, generally known as "the Hierarchy of Controls". The following is a brief summary of how it works and the part which training, warnings, cautions and instructions play within that hierarchy.

Before we begin, let's define the word "hazard". A hazard is formally defined as a condition which has the potential to cause damage, injury or illness. This is a seemingly simple, but important concept. All of safety depends upon the control of hazards.

The most effective way to address a hazard is to eliminate it. The term safety engineers use for this is "engineering control".

As you may expect, total elimination of a hazard is often so difficult or infeasible, that it is not a viable option. Therefore, we must rely upon the next, best control of the hazard, which is to guard it. Guarding most often implies the placement of a physical barrier between the person or property to be protected, and the hazard. However, there are other forms of guarding, such as the use of interlocks or simply spacing the person or property to be protected and the hazard, apart from one another, which is referred to as "guarding by distance".

If it is not practical or possible to eliminate the hazard or guard from it, the next step down the ladder of the control hierarchy is to have the person wear the guard apparatus. This may take the form of hearing protection, goggles, safety footwear, gloves, etc. The term of art for such apparatus is "personal protective equipment", or "PPE".

If the hazard is such that it is unfeasible or impractical to eliminate it, guard against it or employ PPE, then the only remaining option is to rely upon a means of "hazard communication" - informing the individual of the hazard's dangerous propensities through training, instruction, caution or warning. A future posting will delve into the intricacies of hazard communication. For now, it is most important to understand two things about controls. First, the most effective hazard mitigation, short of elimination, is to employ as many of the various controls as possible. Secondly, in any case where we rely solely upon hazard communication, we are employing a control which can not be totally effective unless the exposed individual is 100% diligent, 100% of the time - an impossible standard to rely upon.

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Determining responsibility for safety among multiple employers

It often happens that an accident occurs in a workplace in which a number of different employers were at work. The obvious question: who was responsible for the unsafe conditions which caused the accident? Resolution of that
question involves an analysis of the roles of each of the employers have, on the worksite.

First, there is the controlling employer. That is the one which has overall responsibility for ongoing work activities. On a construction site, this is usually the general contractor. In any other workplace, it is usually the owner of the business or the facility in which the business is located.

Next, there is the creating employer. This is the business which caused the hazard exposure to exist. For example, a mechanic's fall on a construction site might involve the failure of a handrail which was constructed by an ironworker.

Then, there is the correcting employer. This is the entity which had the means for eliminating the hazard or preventing exposure to it. Very often, the correcting employer and the creating employer are one and the same.

Finally, there is the exposing employer, the one which allowed its employee(s) to be exposed to the hazard. This is almost always the one whose employee was injured. The exposing employer also almost always shares some of the responsibility for the accident's occurrence, either due to lack of training, inadequate protective clothing (the term of art used here is "personal protective equipment" or PPE), inadequate supervision or some other failure or a combination of failures, to protect the worker.

In order to entirely escape responsibility for the accident, an employer must demonstrate that:

It had no control over the hazards of the worksite;
It did not create the hazard which caused the accident;
It did not have an opportunity to report the hazard before the accident could occur;
It did not have the means of correcting the hazardous conditions;
It did not have an opportunity to prevent exposure to the hazard (including ordering its employees not to work in the hazardous area), and;
It had no alternative means of protecting the workers from the hazard.

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What's new in motor vehicle accident reconstruction

When we drive modern motor vehicles, we are doing more than operating
our cars or SUV's - we are also operating computers. The fuel and air mix
in the engine, the application of brakes, the instruments - all are constantly
monitored by sensors which send digital signals to computer chips, which
then send commands back to the machinery, to modulate its performance.
One of the chips controls the air bag supplemental restraint system (SRS).
It contains a tiny accelerometer, which calls upon the firing mechanism in
the SRS to deploy the air bag if it senses the rapid deceleration which is
typical of a frontal collision.

But there's more.

Every time some component which is computer controlled doesn't respond
just right, the computer chip's memory stores a "detected trouble code" or
DTC, which remains for a service mechanic to find and use to maintain or
repair the vehicle. These DTC's can be read by a special device called a
"scan tool". The data in the more sophisticated chips includes information
such as the engine's air/fuel ratio, the vehicle speed and the position of
various components of the engine's auxiliary machinery. The SRS chip also
stores the speed, steering and brake setting at the instant air bag deployment
is called for and the instant the air bag actually fires.

Except for a few scan tools which are proprietary to the vehicle manufacturer,
retrievable information from current scan tools is rather limited. However,
beginning with model year 2002, that changed. It will no longer be necessary
for accident reconstructionists to struggle with the complex physics of a
typical crash, in order to determine the vehicle speed. That data will be
readable in the chip. Of course, for the most part, this will only be true in
the case of frontal impacts. With time, we can expect the range of retrievable
information to increase.

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The capabilities and limitations of CRASH3 and other computer based collision reconstruction programs

There is considerable misunderstanding about how computer-generated solutions of collision vehicle speeds are performed and their accuracy. This discussion is intended to inform the nontechnical reviewer of such information.

Computer models of collisions depend upon two types of data. One is based upon damage to the vehicles, and the other uses basic principles of physics, applying Newton's laws of motion. Most of the programs solve the collision both ways and compare the two solutions. If the computed results are nominally similar, the solution is considered valid and relatively dependable. If they are close, the program displays the two solutions and presents warnings regarding the variances. If they are so dissimilar as to call the results into question, the solutions are either not presented or presented with warnings that they are not reliable.

There are two important thing to understand about computer generated collision speed solutions. First, they are dependant upon both the accuracy of the input data and the extent to which the collision occurred in accordance with the program's algorithms (the formulae used to make the calculations). Most complex collisions, in which the vehicles twist and turn, bump into curbs, walls or trees, slide up or down embankments or overturn, simply do not fit the algorithms. Secondly, the program user can too easily manipulate the inputs to achieve the solution which best suits the client, rather than the one which most honestly reflects what actually happened.

Another aspect of computer generated collision solutions is that the inputs describing damage to the vehicles can be very fickle. If they are based upon actual measurement of damage to the vehicle, the accuracy of the results is only as good as that of the user's choice from a range of estimates of the vehicle's strength and stiffness which are built into the program. However, if the actual vehicle was not measured and the damage data is based upon photographs, then the result is a mix of two estimates, and therefore much less likely to be reliable. Also, if good measurements are applied to a poor choice of vehicle strength and stiffness characteristics, the result will again be unreliable.

When all is said and done, computer based solutions of vehicle collision speeds are, at best, nothing more than complex educated guesses. But, if the reconstructionist was honest and direct in his or her work, the results are probably close to the actual conditions. On the other hand, if data was manipulated to fit the desired outcome, the solution is tantamount to high-tech perjury. It is easy to detect whether the work was performed honestly and competently. First, determine if the damage dimensions were based upon measurements of the actual vehicle and were performed by a trained individual. Estimates of damage data are acceptable only if the fact that they were estimates, is volunteered. Secondly, find out how much time the reconstructionist spent on the computer. It only takes an hour or so, at most, to compile and enter the data. If the record indicates that many hours were spent in that task, you can be sure that the data was repeatedly manipulated to arrive at the desired result, rather than to reflect what actually occurred.

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The uses and limitations of ergonomics

In essence, ergonomics is the science of how humans relate to their environment. It is applied in everyday ways that we constantly encounter and unconsciously accept. Two common examples are automobiles and elevators. When we sit behind the wheel of an automobile, we take for granted the fact that we are operating a machine which has been carefully and ingeniously crafted to accommodate seating and almost intuitive operation by almost the smallest women and the largest men. Similarly, even a small child can almost intuitively operate an elevator. If you think about it for a minute, you can't help but marvel at how much thought and ingenuity went into the design of those two machines, and they are but two examples of the use of ergonomics.

The scientific principles necessary to achieve such adaptability were not fully recognized until military advancements in the use of complex machinery, especially relating to avionics, made it a necessity. Thus, ergonomics, which was originally called "human engineering", is a very new discipline.

When we hear the word "ergonomics", most of us conjure up an image of wrist pain while typing on a computer. While it is true that carpal tunnel syndrome, sometimes the cause of such pain, is an ergonomic injury, that one example often leads to oversimplification of the vast and complex subject of ergonomics. Also, tasks that strain or otherwise overwork muscles, tendons and their connections to bones seem to get most of the attention. A lot of the blame for this can be put on OSHA, which has so completely concentrated its focus on musculoskeletal injury in its regulatory efforts, that it has caused most people to think of ergonomics only in that respect. This is a shame, as the subject of ergonomics has considerably greater depth. It includes the use of all of our senses. Anyone who has tinnitus (constant ringing noise in the ears) will tell you that it can be just as debilitating as a nerve injury, such as carpal tunnel syndrome.

There are also those who substantially misuse the topic of ergonomics to claim understanding of things that are well removed from its scientific principles. The most common of those abuses are interpretations of how people respond to warnings, cautions and instructions. Many so-called ergonomic experts talk about people's "expectancy" and how they will react when they are presented with certain scenarios. A lot of very good research has been done on how people interpret certain simple symbols (commonly called "pictographs") and "visual clues" (such as the presence of a sloped handrail to indicate that one or more steps are adjacent). However, all of that effort has arrived at the general conclusion that the reactions are only expected if the person has been previously trained to understand what the pictograph or visual clue means. Thus, the effectiveness of warnings, cautions and instructions are not at all an ergonomic issue.

How do you know if the professed ergonomic expert is competent? There is a very simple test. Just ask the individual what the "bible" of ergonomics is. If the names McCormick and Sanders (authors of the core treatise "Human Factors in Engineering and Design") don't immediately come rolling of his or her tongue, consider finding someone else to assist you.

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Safety Tips and Product Recalls

From time to time, we will publish information of special interest to parents of young children and recalls of household products. Virtually all of the recall information comes from the U.S. Consumer Product Safety Commission. If you think you might have one of those recalled products, you can find more information by checking the USCPSC's website at www.cpsc.gov.

Installing a child seat properly, so that its protective features are not compromised, is not easy. Each Connecticut State Police troop has trained one of its troopers, who will be pleased to do it for you. Just call the troop nearest to you and ask to make an appointment. It only takes a few minutes to gain many hours of peace of mind.
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Attention Wal-Mart shoppers: Approximately 48,000 Holiday Time™ Candle Gift Sets manufactured by Dan Dee International Ltd., of Jersey City, N.J. are being recalled. Wal-Mart has received six reports of the candles catching fire including two incidents that resulted in approximately $6,200 in property damage. Another incident resulted in minor property damage. No injuries have been reported. Two styles of candle gift sets are being recalled. One features three birch bark-covered candles. Each candle measures 3 inches wide but vary in height from 3 to 6 inches. The candles are displayed on a stand with pine cones, cinnamon sticks and red berries. The second recalled candle gift set includes a display stand with three pyramid-shaped candles varying in height from 8 to 12 inches. The candles are either blue with a silver glitter criss-cross pattern or red with a gold glitter criss-cross pattern. Both candle sets were sold under the Holiday Time™ brand name written on the box.

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Approximately 61,000 Reebok Children’s Fleece Quarter-Zip Pullover/Pant Sets are being recalled. The zipper slider and pull on the fleece pullovers can detach, posing a choking hazard to young children. To date, no injuries have been reported. The fleece pullover/pant sets were sold in navy blue/red and navy blue/pink in sizes up to children’s size 7. “Reebok” is printed across the front of the pullover. The pullovers have a hood that can be folded under the collar. Some of the recalled pullovers were sold with matching mittens. The style numbers were printed on the store tag only and end in: 1816, 2816, 3816, 1816N, 2816N, 1814, 2814, 4814, and 5814. The product was sold exclusively at Gordmans, Mervyns, JC Penney, Kohl’s, The Bon, Fred Meyer, Ross, DD’s, Edisons, Macy’s, AJ Wright, and Reebok Corporate Headquarters retail store in Canton, Mass. from September 2004 through February 2005 for between $17 and $36.

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Answers to fire safety quiz 1 - d, 2 - b, 3. - c, 4 - c

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Thank you for your interest and please check back soon.