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Difficulty: MediumWinter Driving

An interstate tractor-trailer approaches a long concrete bridge overpass as the ambient temperature reaches 32∘F32^\circ\text{F} (0∘C0^\circ\text{C}) during a freezing drizzle. Because bridge decks freeze before roadway surfaces on grade, which driving adjustment is most appropriate for maintaining vehicle control?

  1. A
    Engage the auxiliary engine retarder to maximum power so wheel speed drops without applying service brakes.
  2. Reduce speed smoothly before reaching the bridge, disengage the engine retarder, and maintain gentle steering and pedal control.Answer
  3. C
    Maintain normal highway speed while keeping a standard dry-pavement following gap of one second per ten feet of vehicle length.
  4. D
    Counter-steer sharply in the opposite direction of any trailer drift while applying the trailer hand valve firmly.

Answer

Reduce speed smoothly before reaching the bridge, disengage the engine retarder, and maintain gentle steering and pedal control.
Because ambient air circulates under elevated bridge decks, they lose heat rapidly and freeze well before surrounding road surfaces. The correct response is to reduce vehicle speed in advance, turn off engine retarders to prevent drive-wheel spin or skidding, and keep all steering and speed inputs smooth and gradual.

Step-by-Step Solution

1
Identify the hazard associated with bridge decks in freezing weather.
Cold air circulates both above and below bridge decks, causing them to freeze and develop ice before roadways on ground fill.
Recognizing early freezing locations prevents sudden unexpected skids when transitioning onto elevated structures.
2
Adjust speed and vehicle control systems prior to reaching the bridge.
Slow down ahead of time and switch off auxiliary engine retarders/brakes.
Retarder braking applies force exclusively to drive wheels, which can easily induce a drive-wheel skid or jackknife on ice.
3
Navigate the structure with smooth, deliberate control inputs.
Maintain steady directional control with gentle steering and no harsh brake applications.
Abrupt movements exceed available tire traction and cause immediate loss of vehicle control.

Key Concept

Bridge Deck Freezing Hazards and Retarder Deactivation in Winter Conditions
Estimated Time:1m 0s
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Topics

Winter Driving

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