KL was licensed under the United States Department of Agriculture Federal Grain Inspection Service to take samples of grain as it was leaving the elevator and being loaded into train cars. In addition, it was her responsibility to inspect cars to insure that they were dry and free of contaminants prior to grain stowage. She had been an inspector for more than twenty years.

At about 9:00 AM, KL arrived at the A & B Farmers Cooperative Grain Elevator and signed in at the office building. Earlier, she had received a call that the person who was usually responsible for inspecting the cars at the Cooperative had taken ill. More than eight months had elapsed since KL had last been to the Cooperative. After signing in, she walked to the cement silo-like elevator, and ascended a flight of stairs to the control room. Located in the control room was a machine that withdrew samples of grain as the grain moved down a chute into the cars.

Near the sampling machine was the workstation for the A & B employee who was responsible for loading grain into the railroad cars. It contained a large central window and two smaller windows that provided the loader with an excellent view of the grain cars and the grain chute and spout. To the right of the loader's workstation was a door which led to an exterior catwalk. The catwalk provided access to the top of the cars. KL opened the door and walked from the catwalk onto the first of five stationary cars that were positioned along the siding to the grain elevator. Each grain car contained three compartments. Inspection involved peering down into the empty compartment to see if it was dry and clean. KL inspected all five cars and then returned to the sampling machine in the control room.

The loader was responsible for controlling the amount of grain that moved down the chute through the spout into each compartment. When the car was completely loaded, it was weighed. .

The positioning of the spout over each compartment required the coordinated efforts of the loader and the driver of a trackmobile. The trackmobile driver moved the string of five cars to various designated positions along the siding in accordance with instructions given to him by the loader over hand-held radios. It required about an hour to load the five cars, move them out of the way, and then pull the next set of five cars into position.

KL drew grain samples and inspected, in turn, the second and third set of five cars. Following the third set of cars, she gathered the samples she had collected and left the grain elevator. KL stored the bags containing the samples in her pickup truck and then went to the office building to use the restroom.

According to the trackmobile driver, he saw KL when he went to the office building to get a cup of coffee. He informed her that they were starting to load the fourth set of cars. KL and the trackmobile driver walked towards the grain elevator together. She ascended the stairs to control room, while he went back to his trackmobile.

When KL entered to control room, she saw the loader at his workstation. She walked across the room and through the door that led to the catwalk She observed that the cars were slowly being pulled east and that the spout of the grain chute was over Car No. 1's middle (#2) compartment. The cars were not supposed to be loaded until after she completed her inspection and had signaled the loader to proceed. He was relatively new at the job and had started without her consent.

KL believed that she had time to inspect the four remaining cars in the set before the first car was fully loaded and weighed. She stepped onto the top of the car and then walked slowly west.

When she reached the grain chute, she was located approximately 10 feet in front of the loader’s workstation. Even through there was adequate clearance, KL bent her head down as she walked under the grain chute. She did not look to see if the loader was still seated in front of the window. She assumed that since the chute was over the middle compartment, he was seated at his workstation loading grain into the compartment and was aware of her presence.

She then walked to the end of the car and stepped onto a small platform. The next car in line was equipped with a similar platform. She paused to determine how far out she had to step in order to bridge the distance between the two cars.

According to KL, something hit her in the back and she fell in-between the cars.The next thing she recalled was looking up at the bottom of the train car, which was moving. The loader stated that he did not see KL until she was on the platform at the end of the car. He saw the spout of the grain chute strike her. He claimed that he did not have sufficient time to prevent the accident. The trackmobile driver heard screaming, and stopped. He saw that KL was under the second car. As a consequence of the accident, KL's left leg was amputated below the knee and her right arm was shattered just above the elbow.

HF Issues: Why did this accident occur? Did the loader have sufficient time to perceive and evaluate the situation? Could he have radioed the trackmobile driver in time to stop car movement so as to prevent the spout from striking KL? Did KL appreciate that she was at risk of being struck by the spout when she stepped onto the moving car?

HF Investigation: Apart from reading the depositions of all the parties involved in this litigation, I met with KL at the accident site. KL remained on the catwalk outside the control room, while I stepped out onto the top of a car that was similar to the one involved in the accident. I asked her several questions pertaining to her gait and her location at various points in time. Measurements and photographs were taken on top of the train car as well as in the control room at the loader’s workstation. My request to have the trackmobile driver move a set of five cars at a speed and rate of acceleration that was typical of the operation was denied.

HF Analysis:

Expectancy

When KL stepped onto the moving car, she expected that the cars would be loaded and weighed in the manner that were at other grain elevators with which she was familiar.

When KL stepped onto the top of Car No. 1, the chute was located over its middle compartment. Therefore, according to her expectations, the west compartment was empty and the car had not been weighed. KL reasoned that during the time required to perform these operations, she would have ample time to walk west to the end of the first car, cross over to the second car, and then begin her inspection.

However, KL’s expectancy about the sequence of car and compartment loading was incorrect. The railroad siding at the A &B grain elevator sloped downhill to the west. Instead of having the trackmobile pull the loaded cars uphill, the cars, with one exception, were loaded with the trackmobile pushing them downhill. The one exception was Car No. 1. It was loaded first, according to the trackmobile driver, to provide the trackmobile better traction. Then, after Car No. 1 was weighed, the trackmobile pulled all the cars up the grade until the spout was above the west compartment of Car No. 5. From this point on, the cars were pushed downhill as the compartments were being loaded with grain.

• When KL stepped onto the top of Car No. 1, she believed that its west compartment was empty and the car had not been weighed. She was wrong. The car had been loaded and weighed before she arrived, and the trackmobile driver was moving the cars up the hill so that the next car to be loaded would be Car No. 5.

Perception-Response Time

Did the loader have sufficient time to prevent the accident? The speed of the cars was a critical variable in determining how much time the loader had to perceive and respond to the situation. The testimony of various witnesses provided the range of car speeds from "crawling" to 2 mph. For my purposes, this range needed to be narrowed. According to the loader, when the grain spout hit KL, she "flew" and struck the end of the second car. In addition, on the basis of both KL's testimony and that of the trackmobile driver, it was known that after she was hit by the grain spout, she landed on her back under Car No. 2. Could these results be obtained through computer simulation?

I modeled KL in Knowledge Revolution's Working Model, a computer application that permits access to a virtual two-dimensional universe in which mass, gravity, velocity, acceleration, and other physical parameters are simulated. Each of the model's body segments was assigned a mass based on estimates provided by other computer applications (HumanCad and GEOBOD/MAC). KL was modeled as standing on the top of the platform at the end of Car No. 1 facing the east platform of Car No. 2 with a grain spout approaching her backside. There were three experimental conditions for the impact speed of the spout: 3 mph, 2 mph, and 1 mph.

Results

The simulation that provided the best fit with all the available information was for an impact speed of approximately 1 mph. (At 3 mph, the model of KL was hurled onto the platform of Car No. 2. At 2 mph, she was caught in a pinch point formed between the spout and the end of Car No. 2.)

Reconstruction

If the load handler was at his workstation, then the following diagrams show the likely sequence of events that resulted in KL being struck by the grain spout.

During this time interval, the cars were not being loaded and therefore, the loader did not need to attend the spout. The hand radio permitted him to maintain contact with the trackmobile driver while leaving his workstation.)

In addition to analyzing the accident, recommendations were made with the intention of reducing the likelihood of this type of accident occurring in the furture.