Trucker vision can play key factor in accidents. Altered vision can reduce their ability to properly visualize the road, pedestrians, and other moving vehicles. An accident resulting from decreased vision can be disastrous because the mass and speed of a track is directly associated with the force of impact. Reduced trucker vision can result in jackknife accidents or rear end collisions.
Guidelines for trucker vision have been established by the Federal Motor Carrier Safety Administration of the Department of Transportation. Their criteria for visual acuity on a Snellen eye chart includes the following:
- visual acuity for distance viewing of at least 20/40 in each eye without corrective lenses, or
- visual acuity in each eye with correction to 20/40 or better, and distance vision of at least 20/40 or better in both eyes with or without corrective lenses
The visual acuity on a Snellen eye chart represents the central (straight ahead) vision. The Snellen eye chart is the standard vision screen used in ophthalmology and optometry offices when testing vision. Corrective lenses may be in the form of eyeglasses or contact lenses.
Peripheral vision is the “side vision” that is used to perceive objects situated alongside a truck. Cars and pedestrians traveling alongside the truck are perceived in the peripheral vision as the driver focuses on the road ahead of him. However, movement of the eyes in different directions allows a trucker to detect objects off to the side.
The Department of Transportation also specifies criteria for peripheral vision. They stipulate that the field of vision be at least 70 degrees in the horizontal meridian. Visual fields may be tested by a procedure known as confrontation. In confrontation testing the examiner asks the examinee to identify the presence or movement of an object when placed in the peripheral vision. Another method is with computerized perimetry. In general, computerized perimetry provides greater detail and analytic parameters than confrontation testing.
The height and position of a trucker within the cab of the vehicle he is driving is important to consider when determining visibility. The ability of the trucker to see objects in front and off to the side is influenced by his position with the cab. This is known as the observation angle. In certain situations the trucker may have an excellent view of the distance when his position in the cab allows him to peer above the traffic directly in front of him. However, an observation angle that is very high may reduce his visibility of objects off to the side. Under these circumstances, a trucker is more reliant on his side view mirrors.
Color perception is also of concern in truck drivers. The Department of Transportation requires truck drivers to recognize the colors of traffic signals and devices that show standard red, green, and amber. Testing for color vision is commonly performed with books that have color plates. The color plates have numbers that are disguised by various colors making them difficult to identify in individuals who have color deficiencies. The type and degree of color deficiency can be ascertained by various color testing devices.
The ability of a trucker to adequately focus on the road ahead of them is influenced by factors beyond that of visual acuity. Adverse weather conditions such as a downpour of rain or a hailstorm can certainly impact visibility. Truckers driving through foggy road conditions may need to exercise special caution. Distraction with mobile communication devices, certain medications that influence alertness, or undue fatigue are all factors that may need to be considered in trucking accidents.
Issues of trucker vision and visibility are important considerations when analyzing causation involving truck accidents. Testimony from a vision expert may be helpful in understanding the influence of vision and perception in truck accidents.