Chapter 6

Physical Aspects of Driving

Human Error

• 90-95% of vehicle accidents are caused by people not vehicles or roadways.

Vision Problems?

• 90% of driving information is received through the eye

• Affects of a person’s vision:– Genetics– Fatigue– Smoking– Age – Illness– Alcohol or other drugs

South Rowan High School

Visual Acuity(ability to see things clearly—near and far)

• Normal vision 20/ 20 vision

• Minimum acuity 20/40 vision

• Color vision / color blindness

• Field of vision- central, fringe, peripheral

• Depth perception- judge distance between yourself and other object

• Night vision / glare

Field of VisionThe area you can see looking straight

ahead• Central vision- looking straight ahead-it’s

the area where you see things clearly Fringe vision- outside central vision where you recognize objects but not clearly

• Peripheral vision- outside of your field of vision where you see motion but not objects

Field of Vision Affects

• Tunnel vision caused by genetics

• Other traffic blocking parts of your field of vision

• Your vehicle’s design can block you vision

• Illness, even temporary illness can cause vision restriction

• Age can reduce a person’s field of vision

Alcohol as a Sedative

Affects many areas of the body from mental functions to relaxing muscles

Ways Alcohol Sedates the Eyes• Slows the pupil, increasing glare and slow

glare recovery

• Relaxing the muscles that control the lens reducing visual acuity

• Sedating the retina causing problem of color recognition especially shades of darkness while driving

• Binocular vision: ability of the eyes to focus together on an object

• Peripheral vision can be narrowed

Other disabilities that may affect a person’s ability to drive includes:

• Hearing loss- there is usually no increased risk because of visual compensationPhysically challenged persons are not normally a greater risk. Safe driving is a mental skill so physical limitations can usually be overcomeAge affects all of a person’s senses.

Other disabilities continued

• Epileptics are allowed to have a class c license if they are on medication and have gone seizure free for one year.

• Diabetes is a major problem because of the serious effect of high or low sugar

• Mental ability. The DMV officer can ask for medical referral if he/she suspects an individual’s mental ability may be a problem