Ergonomics for transportation

MSDs are disorders of the musculoskeletal and nervous systems which may be caused or aggravated by repetitive motions, forceful exertions, vibration, mechanical compression (hard and sharp edges), sustained or awkward postures, or by exposure to noise over extended periods of time.

In the transportation industry MSDs are most often caused by:

1. Hand loading/unloading materials
2. Improper lifting
3. Cumulative (repetitive) trauma (twisting, bending, and reaching)
4. Moving excessive weight (in excess of 75 lbs., etc.)
5. Improper pushing/pulling

Loading and unloading materials. Manual material handling is one of the most frequent causes of lower back injuries in the transportation industry. The direct and indirect costs of lower back injuries are enormous and the human suffering associated with this type of injury is immeasurable.

The majority of injuries resulting from loading/unloading materials (when proper lifting and back safety techniques are being demonstrated) are caused by overexertion and muscle fatigue. Prolonged strenuous movements, such as that experienced when performing a hand load/unload of a trailer full of freight, can cause muscle overexertion and fatigue. Overexertion and fatigue weakens muscles, and weakened muscles are at greater risk and susceptibility to sprains, strains, ruptured or slipped disks, and chronic tension and stress.

It's important to remember that, even though proper lifting techniques are being used, muscle overexertion and fatigue can happen. Warning signs that muscles are becoming overexerted or fatigued include muscle tightness, spasms, and slight to severe cramps.

Suggested controls and solutions. In all cases, drivers need to make full use of any mechanical loading/unloading aids such as pallet jacks, hand trucks, and fork lifts. In addition, transportation companies should explore vehicle and equipment retrofitting such as trailer lift gate options to assist drivers when required to handle materials.

As with most injury prevention programs, education is generally the best and most effective tool. When performing any hand load or unload, drivers should be trained to establish a slow (albeit steady) pace, take frequent breaks, and take appropriate action if they experience any of the above overexertion warning signs. If muscle overexertion does occur, the best thing to do is rest and apply an ice pack. Ice pack treatment should last 10-15 minutes maximum every hour until pain subsides.

For more chronic back pain due to muscle overexertion, moist heat is the treatment of choice. Again, treat the back pain 10-15 minutes every hour until pain subsides.

Improper lifting. Ounce for ounce, the muscles in the back (particularly the lower back) are among the weakest in the human body. Given this, when a driver attempts to lift cargo with their back, the driver puts an incredible amount of stress on these relatively weak muscles.

Obviously, lifting with one's back is neither correct nor recommended. Yet improper lifting remains one of the leading causes of back injury. Using improper lifting techniques (when engaged in hand loading and unloading activities) are the largest single cause of driver back pain, strain, and injury.

Suggested controls and solutions. Once again, driver education and training is key to preventing injuries caused by improper lifting techniques. Unfortunately, most drivers are not trained in proper lifting and back safety techniques. To reduce the incidence of back injury caused by improper lifting, carriers should institute a comprehensive back safety and proper lifting training program. The following outlines the safe and proper lifting techniques that should be included in such a training program.

All employees should be trained in, and expected to adhere to, the following lifting techniques when they are required to perform any lifting activity as part of their job duties. When required to perform lifting activities, employees (drivers) should be taught the following guidelines:

• Size up the load before lifting: Test by lifting or pushing a corner of the object. If it feels too heavy or clumsy, get mechanical aid or help from another. When in doubt, drivers are expected to obtain help and to never attempt lifting alone.
• Bend the knees: Bending the knees is the single most important aspect of any lifting activity. During any lift, the leg muscles should do most of the work and absorb most of the stress, since they are the body's strongest muscle group. Bending the knees will ensure that the leg muscles are doing the majority of the work.
• Lift straight up: When lifting an object (such as a box or crate), the employee's feet should be positioned as close to the object as possible. The body should be centered over the load. The employee should then bend at the knees and get a firm handhold. The lift should be done as one smooth and straight-up motion — again, allowing the legs to do the majority of work.
• Avoid twisting: Once the object has been lifted, the employee should keep the load close to the body. Any sudden twisting or turning could cause a back injury and should therefore be avoided. This can be accomplished by pivoting the feet instead of twisting the torso, and by making sure the movement is predominantly carried out on a horizontal plane. Twisting or turning while lifting is a leading cause of disk injuries.
• Have a clear path: The employee’s path should be clear of any obstacles, as well as other hazards like spilled grease or oil. Having a clear path will also reduce the risk of a slip, trip, or fall type of incident.
• Safely set the load down: Setting the object down is just as important as lifting it. Train the employee to lower the load slowly by bending at the knees, again letting the legs do most of the work. Don't let go of the object until it is securely on the ground.

Lifting remains a necessary part of many drivers’ jobs despite the level of mechanization found in the workplace today, so attention must be directed toward safe lifting practices. Doing so will help both employees and employers minimize the risk and cost of back injury and pain.

Excessive weight. In addition to overexertion and improper lifting techniques, another cause of musculoskeletal injuries among professional drivers is lifting and moving excessive weight. Because of the variety of materials being transported throughout the country, drivers are sometimes asked (or required) to handle heavy and awkward cargo. Such hand loading/unloading activity can place drivers at high risk for serious injury.

Suggested controls and solutions. Carriers and other transportation companies should institute reasonable guidelines with regard to driver hand loading and unloading expectations (in terms of maximum weight and lifts per day limits).

Specifically, drivers should be prohibited from lifting more than:

• 75 pounds at any one time;
• 55 pounds more than 10 times per day; or
• 25 pounds below the knees, above the shoulders, or at arm’s length more than 25 times per day.

When drivers are placed in a situation where they are asked to perform handling materials that fall into any of the above categories, they should be instructed to contact their supervisor or other company official for instruction. At the very least, drivers should be trained to get help or seek mechanical aid if required to handle materials that meet the above criteria.

Cumulative trauma. Cumulative trauma disorders (CTDs) are disorders of the musculoskeletal and nervous system, which are caused, or made worse, by:

• Repetitive motions;
• Forceful exertions;
• Vibrations;
• Hard and sharp edges;
• Sustained awkward positions; or
• Exposure to noise over extended periods of time.

Due to the nature of their jobs, drivers often find themselves engaged in several of the above behaviors and situations. For instance:

• The act of repeatedly up- and down-shifting gears in a large truck or tractor can put stress on a driver’s ankle, knee, hip, shoulder, elbow, and wrist;
• The forceful exertion of hand loading or unloading a trailer full of cargo;
• Prolonged exposure to engine idle vibration while driving the truck or tractor; and
• Exposure to high levels of noise while at a customer’s dock or manufacturing facility to name just a few.

CTDs affect the nerves, tendons, and muscles. Hands, wrists, elbows, and shoulders are most frequently affected. These injuries develop gradually and result from repeated, forceful actions, such as twisting and bending of the hands, arms, wrists, and fingers.

Suggested controls and solutions. Today’s trucks and tractors are more driver-friendly and designed with ergonomics in mind. In fact, it would be hard to find a late model truck that doesn’t have power-assisted steering and an ergonomically designed control panel.

In addition to the above, look for equipment that includes such things as ergonomically designed driver seats, interior noise reduction features, air-ride suspension that reduces interior vibration, and automatic transmissions.

Early preventive measures and detection are usually the best defense against CTDs. The following are some simple stretching exercises that can help in preventing CTDs.

1. Body stretch: Stand up straight, raise arms over the head with hands close together, and reach for the ceiling. Hold this position for 5-10 seconds, and repeat 3-5 times.
2. Shoulder blade stretch: Clasp hands behind head and try to pinch shoulder blades together. Hold this position for 5-10 seconds, and repeat 3-5 times.
3. Shoulder shrugs: Slowly shrug shoulders five times, raising shoulders as far as are comfortable. Repeat 3-5 times. If pain or discomfort is felt, then the shoulders are probably being raised too high.
4. Shoulder rolls: Slowly roll shoulders five times forward, then five times backward. repeat 3-5 times.
5. Head tilts: Slowly tilt head to the right, stopping when the stretch is felt. Then slowly tilt head to the left. Repeat twice.

Drivers (and all employees for that matter) should be trained to use the above exercises on a daily basis.

Carpal tunnel syndrome. Carpal tunnel syndrome (CTS) is probably the best known of the cumulative trauma disorders. Though it is most often associated with office workers who spend long hours at a computer, it can also affect drivers.

CTS develops in the hands and wrists when repetitive or forceful tasks are performed over a period of time (such as shifting gears, grasping the steering wheel, or loading and unloading cargo). This can cause tingling, numbness, or severe pain in the wrist and hand. The pressure of repetitive motion also results in a lack of strength in the hand as well as an inability to make a fist, hold objects, or perform other manual tasks. If the pressure continues, it can cause permanent loss of sensation or even partial paralysis.

The vibration of the vehicle’s steering wheel can cause a driver to place a stronger grip on the steering wheel. Over a period of time, this can lead to CTS. Repetitive motion when loading and unloading freight can also contribute to CTS.

Carpal tunnel syndrome prevention. The following are two exercises that are easy to do and can help prevent CTS.

1. Rest forearm on the edge of a flat surface (table, desk, etc.) and gently bend back the wrist by grasping fingers with the other hand. Hold for 5 seconds.
2. Clench hand into a tight fist, then slowly release until fingers are fanned out. Repeat 5 times.

Improper pushing/pulling. Aside from performing hand loading and unloading tasks, raising and lowering of the landing gear of a trailer (or trailer frame) is another area of concern with regard to most driving jobs.

The landing gear of a trailer is the component that allows a trailer to stand securely without being attached to a truck or tractor. When a trailer is attached (via a fifth wheel assembly) to a truck, the landing gear must be raised so that the legs do not come into contact with the road surface. Conversely, when disconnecting a trailer from a truck, the landing gear must be lowered so that the vehicle can safely pull out from under the trailer.

The act of lowering and raising a trailer’s landing gear is done through using a crank, or turning handle, located on the side of the trailer. When performing this task, if the driver uses improper pushing and pulling techniques, injury to the driver's neck, shoulders, or back could result.

Suggested controls and solutions. Again, employee/driver education and training is critical. Employees should be trained on proper and safe pushing and pulling techniques including:

• Taking the proper stance: Feet should be at shoulder width, with legs bent slightly at the knee. The right leg should be placed approximately one step behind the left. Then with the back remaining as straight as possible, the driver should firmly grab the landing gear crank.
• Using the proper amount of force: The driver should turn the crank slowly, allowing the shoulders and arms to do the majority of the work. Never force the situation. If the turning motion is too difficult or appears stuck, drivers should be instructed to notify a maintenance personnel or their supervisor. Forcing can cause severe muscle strain, or lead the driver to slip.
• Safely completing the task: Once the trailer has been sufficiently raised or lowered, the driver needs to secure the landing gear crank in its holder.

Other topics provide more detail about specific aspects of ergonomics. Please see the topic(s) above.