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BACK TO BASICS: a review of defensive driving techniques
10: Driving Environments: INCLEMENT WEATHER & SPECIAL HAZARDS
Often a driver will be forced to modify his or her driving techniques to fit the existing conditions. The challenge may be a slippery road surface, an irregular or obstructed roadway, decreased visibility, or erratic drivers, but the primary means of adjusting for any of them is to increase following distance and decrease speed. Technically these are environmental modifiers, not environments themselves, but they introduce enough variation to significantly alter the driver's considerations and actions.
Slippery conditions, whether due to water, ice, dry powder, or spilled chemical or petroleum product, can increase stopping distance by a factor of 3 to 12. To compensate, make turns gently, avoid passing or driving beside others, and adjust speed to minimize braking. Appropriate tires or traction devices are an excellent aid if there is prior warning of the road condition. Water can cause problems without rain. Hydroplaning can occur whenever the roadway is wet and shiny, and contrary to common belief, weight is not a significant deterrent: the principal factors are road surface, tire condition, and speed. Skid correction training should be provided for both drive-wheel and front-wheel skids. Drive-wheel skids normally are caused by over-braking. The rear wheels slide to "catch-up" with the front causing the vehicle to turn sideways or spin out. Similarly, a trailer may push the towing vehicle sideways resulting in jackknifing. To correct a drive-wheel skid, stop braking (declutching if necessary) and steer quickly in the direction you want to go, being ready to counter steer as needed. Front-wheel skids are generally caused by driving too fast, and the only way to stop such a skid is to slow the vehicle, preferably not so quickly that a drive-wheel skid is incurred.
An irregular or obstructed roadway may be caused by construction, detour, or accident. Because of the unusual activity, all require increased scanning, and radical reduction in speed; more attention to control is needed if the surface is bumpy. Such areas are made more hazardous by any restriction of visibility.
Decreased visibility from rain, snow, sleet, fog, blowing dust, steam rising from the pavement, or darkness demands reduced speed if following distances are to be maintained, even on satisfactory surfaces. Since following distance must exceed stopping distance and be within the limits of visibility, when visibility is reduced to a couple of vehicle-lengths, speed must be decreased radically. When visibility is reduced by weather conditions, the windshield wipers should be operated fast enough to maximize visibility, the defroster should be used to combat condensation, and the headlights should be on to announce your presence. Darkness is the most frequently encountered limit to visibility, but too much light, such as glare from snow or from wet or icy pavement is also detrimental. If visibility is reduced by glare during the daytime, use the sun visor and sunglasses, but never wear sunglasses at night even to reduce headlight glare. If oncoming headlights cause a problem, avoid looking at them by focusing on the right shoulder until the offending vehicle passes. Never flash your high beams as this may blind the other driver and cause him or her to swerve into your lane or into the ditch. To improve visibility at night, use high beams when it is safe, e.g., on rural or limited-access roads, remembering to dim them when within 500' of any vehicle in front of you. Do not exceed the range of your headlights and remember that range is diminished on curves as the lights are shining off the road during the actual turn.
Erratic drivers, whether just tired or under the influence of alcohol or drugs, are more prevalent at night. If you encounter them, slow down, increase your following distance, and resist every temptation to pass.
Notify the authorities if possible. Any vehicle that is weaving, driving without lights or driving out of the traffic flow is extremely dangerous as it may invade your space for life suddenly and without warning.
INCLEMENT WEATHER & SPECIAL HAZARDS... A BRIEF RECAP
| Who is responsible: |
You...
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| Slippery road: |
General: increases stopping distance 3 to 12 times
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Causes:
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water
ice
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dust or dry powder
chemical or petroleum spills
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Controls:
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increase following distance
reduce speed
appropriate tires or traction devices
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Drive-wheel skid:
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Controls:
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stop braking
steer quickly in direction desired
be ready to counter steer
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Front-wheel skid:
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Cause:
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speed too fast for conditions
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Controls:
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slow down without inducing drive-wheel skid
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Hydroplaning: (may occur anytime the roadway is wet and shiny)
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Cause:
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road surface
speed
tire condition
not insufficient weight
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Controls:
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slow down without inducing drive-wheel skid
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| Obstructions / irregular surface: |
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Cause:
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construction
accidents
poor maintenance
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Controls:
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increase scanning because of unusual activity
decrease speed
increase following distance
increase attention to control because of irregular surface
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| Decreased visibility: |
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Cause:
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rain / sleet
snow
blowing dust
glare
night
fog
steam rising from the pavement
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Controls:
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decrease speed
use defroster
use headlights
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increase following distance
use windshield wipers
use visor and sunglasses (day only)
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Night Issues:
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do not drive beyond the range of the headlights
use high beams on limited-access and rural roads
dim for any vehicle within 500' in front of you
if blinded by oncoming headlights
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8look off to right shoulder until the vehicle passes
8do not flash high beams
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| Erratic drivers: |
Decrease speed, do not pass
Increase following distance
Inform authorities if possible
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