What is 'rearward amplification' and which combination vehicle is most affected by it?

REARWARD AMPLIFICATION ('crack-the-whip'): The effect where a steering movement by the tractor is AMPLIFIED as it travels back through the combination — the rear trailer swings with greater force and distance than the tractor. MOST AFFECTED: DOUBLES and TRIPLES (multiple trailers) — the more trailers and connection points, the greater the amplification; the LAST trailer in a triple can experience amplification several times the tractor's movement, swinging violently and potentially rolling over or leaving the lane; CONTRIBUTING FACTORS: quick steering movements (sudden lane changes, abrupt evasive maneuvers); higher speed; SAFE DRIVING with doubles/triples: steer smoothly and gradually (avoid sudden movements); reduce speed; increase following distance; avoid abrupt lane changes; be especially cautious in evasive maneuvers (a quick swerve can cause the rear trailer to roll over); SINGLE trailers have less amplification; the more trailers, the more conservative the driving must be; rearward amplification is a key reason doubles/triples require their own endorsement and careful, smooth driving; this concept is tested on the doubles/triples endorsement especially.