Ergonomics and Driving
Why is it Important
As our reliance on the automobile increases due to long distance job commutes driving has become a significant part of our daily routine. By spending more and more time in cars our driving can now be considered a major source of physical and psychological stress in day-to-day living. With 180 million drivers in the United States men drive an average of 44 miles and women drive an average of 34 miles per day.
Stressors of Driving
The challenge of the manufacturer is to strike a balance between safety and comfort. With current seat design being far from perfect we must examine potential sources of stress facing the modern driver. With the prime ergonomic elements being posture, force and repetition it is posture that is most important to the driver. Any deficiencies in postural design of the car seat contribute to tension and fatigue on the part of the driver and subsequently detract from performance. There are portable support systems/commuter supports designed to be added to the existing car seating. These compensate for ineffective car seat design.
Neck and Shoulder Pain
With long distance driving we have all experienced aches and pains in our legs, low back, mid, upper back and neck. With our hands on the steering wheel and the forward posture of the shoulders there is added stress on the shoulders and upper back.
To prevent rounding of the shoulders the driver must have easy access to the steering wheel without having to fully extend the arms and at the same time comfortably reach the foot pedals without having to stretch the legs. The forward and backward linear adjustability of the seat must accommodate people of different sizes.
Two major contributors of neck pain while driving are insufficient headroom and inadequate seat positioning. Compact vehicles are notorious for poorly accommodating tall individuals. If the ceiling is too low for an erect seated position the driver is forced to crunch down in the seat with a forward head posture. This is sure to elicit neck and upper back pain. Short drivers must be able to slide the seat forward to the extent that they do not have to lean forward and place the head in a forward position.
It is common for drivers to lean forward in the seat in order to comfortably reach the controls while driving. The result is not only strain and fatigue to spinal muscles but this creates a significant gap between the head and headrest. In the event of a rear-end collision the head and neck are vulnerable to whiplash injury because the gap allows the head to go backward into hyperextension. The research on whiplash indicates that the greater the gap between the head and the headrest the greater the injury. There are add-on headrest supports that close the gap between the head and headrest. One study found that 97% of the existing car headrests provided inadequate neck support and only 3% were rated as good.
Low Back Pain
Several studies have shown a relationship between driving and low back pain. Risks of both low back and neck pain tend to increase as daily driving time increases. For example, a French study found that low back pain was found to be a significant problem for men who drove at least 4 hours per day.
The lumbar spine has a natural resonant frequency of 4-5 Hz. When driving causes the body to resonate at this frequency due to whole body vibration the low back becomes vulnerable to stress and injury.
With the angle created by the seat pan and seat back being 90 degrees or less a great deal of pressure is put on the lower lumbar discs and back muscles. Over time the resultant forces contribute to low back pain and degeneration of the lumbar spine. These conditions have especially been observed in people whose occupation requires a great deal of driving. Loss of rigidity or sagging of the seat-pan (due to the wear and tear) can also have the same effect. As a result the knees become elevated to a higher level than the pelvis and this causes gravity forces of the upper body to concentrate at the lower lumbar spine. The solution is to add foam wedges to the seat-pan to elevate the pelvis.
For people with a history of low back problems it is recommended that they choose a vehicle with a higher curb height so they are not traumatized when getting in and out of the car. The driver should enter the car first by sitting down and then swinging the legs under the wheel. To leave the vehicle the seat should be slid back before swinging the legs out to plant the feet on the ground.
Features that are included in most modern vehicles include automatic transmissions and power steering. These features lessen any twisting of the spine and strain to the low back.
Leg and Thigh Pain
Pain at the back of the thighs is most likely due to pressure from the front edge of the seat-pan. A flaring (curved) of the front edge serves to effectively reduce the pressure of the thighs and legs behind the knees. Foam wedges for the seat pan take pressure off the lumbar spine and back of the thighs.
Technologies That Make Driving Easier
There are electronic sensing devices that serve to improve visibility to areas normally out of the drivers view. Rapid turns of the neck to see traffic behind or to the side is avoided by utilizing this technology. The driver should have immediate input of information so as to make quick responses to traffic situations without taking time to move out of a neutral driving position. Many whiplash accidents take place when the driver is out of his normal driving position thereby increasing the severity of injury.
Sensor devices are now available that can be mounted on side-view mirrors. These sensors give off a signal when a vehicle or object comes too close to the side of the vehicle. They can also be mounted on the front and back of the vehicle or in the garage to aid the driver in parking safely. They compensate for blind spots and areas that have poor driver visibility.
We now have parabolic type rear-view mirrors that clip on to existing mirrors to extend the range of visibility to the rear corners of the vehicle. Some of the large RVs have rear-mounted cameras that replace the need for rear-view mirrors.
Map softwares based on GPS technology aid the driver in navigation and are becoming widely available to the public. It is especially invaluable to delivery and service businesses that depend on a driver getting to a location in the fastest and most efficient way possible.
Experimental computerized self-driven transport vehicles have been developed in Europe that are designed to travel caravan style and without the need for human occupants.