Fighting fatigue
January 26, 2009 By: P&Q Staff Pit & QuarryAround-the-clock operations are commonplace in the mining industry. The search is on to help those who experience the fatigue that goes with shift-work. Operator fatigue is proven to be one of the most prevalent causes of accidents within the mining industry. In the surface mining industry alone, some 60 to 65 percent of truck-haulage accidents are directly related to operator fatigue.
Mining companies have long been aware of the dangers of fatigue and have tried to manage the situation through policies and procedures, and through various education, training, scheduling, diet and motivational efforts.
“These techniques all help deal with the root causes of fatigue,” said David Edwards, an ergonomics research engineer who studied operator fatigue in Caterpillar Inc.’s Technology and Solutions Division before joining the new Caterpillar Safety Services Division.
“At the end of the day, there are still people falling asleep,” he added. “That’s why everyone in the industry is desperate for a new solution -- a technology solution -- to help better manage fatigue.”
The cost of fatigue
Sleep deprivation, fatigue and drowsiness decrease awareness, diminish attention spans and increase reaction time -- all significant factors that contribute to accidents. The UK reports over $2 billion in fatigue-related accident costs. Australia’s Transport Safety Bureau reports that 30 percent of all fatal crashes are linked to fatigue. Commercial on-highway truck collisions due to fatigue are estimated to account for 1,200 deaths and 76,000 injuries a year in the United States, at an estimated cost of $12.4 billion to the commercial trucking industry.
Fatigued drivers often are not aware of their condition, frequently driving for up to 30 seconds with their eyes totally closed -- a situation known as micro-sleeps. Studies show that driving drowsy is equivalent to being under the influence of alcohol or drugs and that drowsiness impairs the ability to make decisions. Signs of fatigue include:
• Sleepiness/difficulty keeping eyes open.
• Excessive yawning.
• Blurred vision/loss of focus.
• Irritability.
• Becoming quiet and more withdrawn.
• Inability to concentrate.
• Inability to remember activities of the last five minutes.
• Lacking motivation to do the task well.
Studies in the mining industry indicate that fatigue affects even those with the best training and years of experience. Human error due to fatigue is not fundamentally a behavioral problem -- it’s primarily a problem of human physiology.
Managing the situation
Ergonomic improvements in the operator environment have helped lessen fatigue. Education, training and biocompatible scheduling also have proven to be important tools.
“Miners can learn the importance of a good diet -- what foods to eat to keep them alert and help them maintain energy levels,” said Bill Sirois, senior vice president of Circadian Technologies Inc., an international research and consulting firm that assists shift-working companies. “Workers also can learn the right behaviors at work and at home that help minimize drowsiness.”
A lot of sites have started educating the families of employees about how to best support their family members for shift-work. More and more companies also are converting to user-friendly work schedules to alleviate as much of the physical stress of shift-work as possible, Sirois said.
In conjunction with Circadian Technologies Inc., Caterpillar will introduce a CD/DVD designed to educate supervisors, operators and their families on things they can do to lessen fatigue. “Caterpillar used its resources to create an educational tool that we can share with every mine site,” Edwards said.
While an educational video will be helpful, Caterpillar customers have made it clear that they’re looking for additional solutions -- in particular those that take advantage of technology to detect the onset of fatigue and interface with the operator and dispatcher to elicit a response.
“There has been a major effort to develop technologies to monitor fatigue, but they have been primarily for automotive use -- particularly with on-highway trucks,” Edwards said. “There isn’t one technology that has come to the forefront for use in the mining industry.”
Caterpillar and mining companies have tried to leverage existing automotive technologies to adapt them for mining, but have met with little success.
“We started thinking we would have more success if we can get to the source and get them interested in mining,” Edwards said. “Then we could develop a technology that is focused on mining from the beginning.”
Caterpillar is providing funds and access to mining equipment that allows research and development groups to work on a fatigue management solution for the industry.
“We want these researchers to see the differences between on-highway trucks and large mining trucks and their environments,” Edwards said.
“We need to increase awareness in the scientific community that there is a need for them to provide solutions to help miners and mining companies mitigate the effects of fatigue.”
Advancing existing technologies
Caterpillar recently partnered with customer BHP Billiton to study existing technologies and promote the advancement of the most promising solutions. Results of that study will be published and shared with the world to advance the cause, Edwards said.
“Along with Circadian Technologies, we evaluated all known technologies that are commercially available or will be emerging in the next three years,” Edwards said.
The goal of the study was to:
• Identify the most promising technologies.
• Develop an objective assessment tool.
• Score each technology.
• Examine the feasibility of incorporating the best technologies into mining applications.
“We came up with a list of 35 technologies in all industries, and shortened that list to the 21 we felt were the most viable,” Edwards said. “We then tested the leading technologies through driving simulation studies and field trials.”
Two main types of technology exist: “fitness for duty” tests that check operator fatigue levels prior to their shifts, and systems that measure operator and machine behavior during operations. These technologies measure:
• Machine behavior
- Lane deviation.
- Steering wheel movement.
- Pedal usage.
- Machine movement.
• Operator physiological conditions
- Eye behavior (blink and pupil response properties).
- Heart rate.
- EEG.
• Operator behavior
- Head nodding.
- Mental and physical reaction times.
Fitness-for-duty tests have been in use for some time to check operators for drug and alcohol usage. New technologies are being employed to test for fatigue, including:
• Pupilometry -- measures eye reflexes, pupil constriction and the speed of eye movement. Degradation of reaction times can indicate impairment.
• Psychomotor Vigilance Tests -- evaluate reaction times and hand/eye coordination. Using a computer mouse, trackball or joystick, operators must follow a target and maintain their position.
“These units are not cost-prohibitive,” Edwards said. “They range from $5,000 to $10,000 per unit and they are rock-solid for drugs and alcohol. We’re still evaluating how well they work for fatigue, or more precisely, impaired alertness.”
Systems that monitor operator activity in the cab as well as vehicle activity also show promise. These systems monitor the operators around the clock, sometimes sending information to dispatchers as well as accumulating long-term data about the behavior of an operator or his or her machine.
On-board technologies include:
• In-dash cameras or eyeglasses with sensors that monitor eye movement and blink speeds -- both indicators of fatigue. In-dash systems can have difficulty with vibration or motion in the cab, making the glasses a more viable option, Edwards said. The eyeglass system, called Optalert and made by Sleep Diagnostics Pty Ltd., costs about $10,500 per truck. The price includes three pairs of glasses and system hardware.
• Monitors that measure steering wheel and machine movement. When operators are awake and alert, they maintain consistent position within their lane. When they get drowsy, movements are more erratic and machines swerve and sway. The leading system of this type is ASTiD made by Pernix Ltd. and costs less than $10,000 per truck. Unlike the eyeglasses, this system is passive to the operators.
Managing information
One of the technology systems investigated helps mine sites manage the information gained through monitoring -- a feature Edwards can see as the future of fatigue management technologies. Data goes to a dispatcher, who has a log of the operator’s habits and can suggest a break or recommend the operator end his shift.
Edwards said it’s important to make someone other than the operator aware of any fatigue issues. “An operator who is fatigued is the worst judge of how tired he really is,” he said. “That’s like asking a drunk person if they believe they are too intoxicated to drive.”
Studies suggest that users strongly prefer systems that require as little personal monitoring and contact with the technology as possible. The preference is for systems that monitor vehicles instead of people.
“There are a lot of confidentiality issues, in particular with the operator measurements,” Edwards said. “The operator could have a perception that being personally monitored is a bad thing -- so they may choose not to use a given technology.”
Recommendations
“Good technologies exist and we think they are viable,” Edwards said. “The question is, ‘How do you create a technology that deals with the world, and works for all?’ The answer is, ‘You can’t.’ We know we must have multiple solutions because all current technologies exhibit shortcomings when the application range is too broad. In other words, they don’t work for everyone in every situation.
“There are some things you cannot change,” he continued. “You will always have people falling asleep no matter what you do. People are simply not designed to be awake at night. No matter how much you do, you can’t prevent it from happening. The best thing you can hope for is to manage and mitigate the risk.” His recommendation is to use a combination of technologies.
“The Optalert glasses and ASTiD steering system performed best in the lab testing. The ideal solution in the long term would be to fuse these types of technologies together. A system that combines information from both the machine and the operator is the best hope for robustly detecting fatigue and drowsiness in the future. That’s what we’re recommending to the developers.”
Cat will continue to provide support for research and development and allow access to Cat machines for companies to test their products.
“They are the experts,” Edwards said. “We’re not in a position to put this equipment on a machine at the factory. The technology is too immature at this point. But we can try to influence developers to move quickly.”
The most important aspect of a successful fatigue management program is taking responsibility. “We must ensure that people recognize and take responsibility for their own fitness for work,” said Michael Farmer, global practice leader for fatigue management at BHP Billiton. “Frontline supervisors must understand and manage their workgroups, and companies must develop a culture that encourages workers to report and take action on drowsiness and fatigue risks.”
Edwards said he is proud of Caterpillar’s focus on this important topic. “We’re working to meet the mining industry’s needs, the customer’s needs and to energize the research community to care,” he said. “We’ll share this with the world and hopefully all companies can benefit. And we can make the world a safer place to live and work.”
Caterpillar Inc., www.cat.com
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