Slip and Fall

DESCRIPTION OF EVENT LEADING TO ACCIDENT

The Plaintiff, while walking through the produce section of the supermarket, slipped and fell on a grape that was on the floor. The Plaintiff incurred injuries.

OBSERVATION AND ANALYSIS

The type of tile floor covering supermarket produce sections have is common and generally safe as long as the surface remains dry and free of debris. When the floor surface becomes wet it becomes slippery. When produce items fall on the floor and are stepped on by customers, they squash as in the case of grapes, or they become sleds as in the case of leafs. Specifically, and in this case the squashed grape became a “slipper bearing” under the foot of the Plaintiff causing his right foot to loose its traction and slip forward causing him to fall back onto his left hip. Because the floor tiles were set on a concrete under floor the surface of the floor was  hard and not energy absorbing. The floor was not constructed with energy absorbing material. The contact between the Plaintiff’s hip and the hard floor resulted in the Plaintiff’s injuries. Because there were no mats of any type covering the floor of the produce section, the presence of liquid and/or organic matter on the floor would cause the surface to become slippery. Therefore a hazardous and dangerous condition to pedestrians walking through the produce section of the supermarket existed. It was known that grapes or other leafy fruits and vegetables could have rolled off of the sloped display counters as a result of customer handling. Mats should have been placed within the entire produce section of the store where the potential wet and/or slippery condition was anticipated. It was common practice in supermarkets to place mats on floors where water or other slippery items can fall to the floor and create a slipping hazard to pedestrians.The Plaintiff described his fall as his leg slipped out and he went down. This described a typical fall on a low static coefficient of friction surface. The grape on the floor would act as a “slipper bearing” and lower the static coefficient of friction available between the heel of the shoe and the floor surface. Simply stated, the grape interfered with the contact of the two surfaces.
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Review of basic friction forces. When the surface of one body comes into contact with the surface of another body the reaction forces can be resolved, or separated into two components. One component is parallel to the contact surface and the other component is perpendicular to the contact surface. The force perpendicular to the surface is called the normal force (N). The component parallel to the contact surface is the frictional force (f). When there is no relative motion between the two bodies, the resistance to motion is called the static friction force (f). The frictional force between two bodies always opposes the relative motion between the two bodies. The static frictional force will increase as the force tending to cause sliding between the bodies increases. When the force tending to cause sliding (motion) exceeds the friction force, motion occurs.C. A. deCoulomb, in 1781 provided some of the earliest information on the laws of friction. A. J. Morin conducted experiments and published them in 1831 confirming deCoulomb’s results. Their work led to the following laws of friction for dry surfaces:The maximum frictional force that can be developed is proportional to the normal force.The maximum frictional force that can be developed is independent of the size of the contact area.The limiting static frictional force is greater than the kinetic frictional force.

If we look back at our high school physics class when the instructor demonstrated the static coefficient of friction, he put a block of wood on an inclined plane (surface). When the block of wood began to slide down the plane, he measured the angle of the inclined plane. By using the free body diagram it was proven that the tangent of the angle of the plane was equal to the static coefficient of friction. The figure above demonstrates the inclined plane with a block.

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Now let us rotate the angle formed by the inclined plane and place it on a datum. We add a torso, a leg, and arms and a head to represent the stick figure of a person walking. The figure indicates that as the stride length increases, (an increasing angle), the higher the static coefficient of friction becomes to keep the heel or sole from slipping. Conversely, the shorter the stride, (a decreasing angle), the less static coefficient of friction is necessary to keep the heel or sole from slipping. We know this from our own experience, for example, walking around a tiled pool, or walking on ice, a person takes shorter steps, i.e. smaller angle between the leg and the vertical.If a pedestrian is walking on a dry surface the stride he/she becomes used to is a long stride, or the angle between the forward leg and the vertical of his/her body is larger than if he was walking on smoother surface. When the pedestrian passes from a dry surface to a wet or slippery surface and does not adjust his/her stride, the static coefficient of friction of the wet, slippery surface may not be adequate to resist the forward heel from slipping. This is why the Plaintiff’s front foot slipped out in front of him. The walking surface was wet and slippery with a lower static coefficient of friction.Refer to the deposition of the Plaintiff where the following questions were asked and answered;Q. Where were you looking when you walked down the aisle in the produce department?
A. I don’t know, straight ahead, I guess.
Q. Did you ever look at your feet as you walked down?
A. No.
Q. Did you ever look at the floor?
A. No.
Q. Had you been through produce departments before?
A. Certainly.
Q. Do you know that grapes sometimes are dropped by customers or otherwise fall on the floor in the produce department?
A. Probably I did, it probably happens.
Q. That’s not a unique situation with the supermarket, is it?
A. I don’t know, I don’t, I don’t take care of the supermarket’s floor.The question the defendant’s counsel, asked the Plaintiff was a question that assumed, that it was common knowledge that store customers dropped grapes or that grapes otherwise rolled off of the display counters and onto the floor of the produce section. This question asked by the defendant’s counsel showed that the defendants knew that grapes and other produce would fall on the floor. Yet they took only the minimal precautions of sweeping at various set time intervals. With the knowledge that items fall randomly from the display counters, the defendants did not consider placing mats along the produce floor, a relatively inexpensive cost for pedestrian safety.

Refer to the deposition of the plaintiff, where the following questions were asked and answered;

Q. Do you know about the time of day the accident happened at the supermarket?
A. I think it was just before noon. The accident occurred approximately at noon.

Refer to the Defendant’s Answers to Interrogatories, which stated;
The produce aisle is swept at approximately 10:00 a.m., 2:00 p.m., and 4:00 p.m. each day and is also a part of the entire store sweeping between 9:00 a.m. and noon and again at approximately 5:00 p.m. each day. In addition, the aisle is cleaned and items are picked up as needed twenty-four hours per day.

The defendants knew that grapes or other organic vegetables and fruits could and would fall from the display counters because of customer handling. Yet they relied on a specific timetable to sweep the produce floors. Based on the above schedule of sweeping debris could collect on the produce floor for approximately 4 hours before it was swept up.

The case was settled.

Last update: 09/12/2009