A heavy transport vehicle is approaching a severe terrain change during a rainstorm: the level roadway abruptly drops into an 8% mountain grade, starting instantly with a sharp right-hand curve. To maintain vehicle control, prevent brake fade, and avoid a drive-axle skid, arrange the required defensive driving actions in their precise chronological order.
- 1Decelerate the vehicle to a target speed significantly below the posted advisory limit prior to reaching the terrain transition.
- 2Engage a transmission gear lower than what would be required to climb the same grade, completing the shift before the descent begins.
- 3Deactivate the auxiliary engine braking system to prevent sudden drive-wheel lockup on the slick, curved surface.
- 4Navigate through the curve's apex while maintaining steady control without applying the service brakes.
- 5Execute the snub braking technique by firmly applying service brakes only after straightening out on the descent.
Answer
The correct sequence is: decelerate on the flat, select the low gear, disable the retarder for the wet surface, navigate the curve without braking, and finally apply snub braking on the straight downgrade.
Safe heavy vehicle operation requires preemptive action. Speed must be shed and gears engaged before gravity takes effect. Traction management dictates that retarders be disabled on wet curves to prevent jackknifing, and physics dictates that braking during a curve compromises cornering grip. Therefore, braking must be reserved for the straight portion of the descent.
Step-by-Step Solution
Key Concept
Synthesizing curve entry procedures, wet-weather retarder management, and downgrade snub braking into a single chronological safety sequence.