21 Driving in Hazardous Conditions: Nighttime and Weather Flashcards
Traffic fatalities occur _______ more often at night than during the day.
3x
Factors influencing night crashes:
- Impaired drivers
- Drowsy drivers
- Headlight limitations
- Nighttime visibility issues
The overall level of lighting will influence the ___________________ which a person can detect and identify an object.
speed, accuracy, and distance
Seeing at night:
- Conspicuity
- Contrast
- Glare
- Age
On average, low beams project approximately _________ in front of the vehicle on a clear night. High beams ________.
250 ft / 500 ft
Effective range of headlights depend on:
- Aim of the headlight
- Age and condition of the headlight,
- Weather conditions
- Mounting height
- Type of headlight installed
Dirty headlights can reduce the amount of light by:
27%
Two lane highways may present the “worst-case” scenario for nighttime glare. Reasons:
- Lower light levels
- Oncoming traffic closer to driver’s line of sight
- Complex roadway geometry
- Less restricted roadway access
- Fewer roadway markings
- Closer proximity of pedestrians
Beam of headlight is biased towards the ________ side of the road.
Right
The headlight bias helps prevent too much ___________ from affecting an oncoming driver.
glare
Driving in Inclement Weather:
- Rain
- Snow
- Fog
- Ice
- Sleet and Freezing Rain
- Wind
Rain is the most common cause of weather related fatalities…
- Visibility (lowered)
- Friction (loss)
- Hydroplaning
- Windshield Wipers
- Window Fog
Issues with visibility in rain:
- Driving rain obscures forward sight distance
- Driving rain at night can create additional hazards as effectiveness of headlights will be reduced.
- Rain covered roads will make it more difficult to see the road markings
- Rain can cover and obscure glass beads used as reflective material in many road markings
Rain can have a significant effect on the __________________ of the roadway. (Especially within the first 30 minutes)
coefficient of friction
Defogging a windshield:
- Turn the temp setting to high heat
- Turn on the defroster to full fan
- Turn on air condition
- Turn off vehicle recirculation and use fresh air
- If defrosting is needed immediately, open a window
Snow:
- reduces forward visibility
- Obscures signs
- covers roadway markings
- Night: block headlight beams
Ice
Can increase stopping distance as much as 4x
Black Ice
More common in shaded areas, on bridges, and under passes.
Stiffer tires and air brakes will reduce the braking efficiency of the vehicle to approximately 65% that of a civilian vehicle.
