Why is the combination of liquid surge and an icy road especially dangerous for a tank vehicle driver, compared to surge on dry pavement?

49 CFR 383.119(a) (effects of cargo surge on vehicle control); AAMVA CDL Manual Section 8.2.2, p.8-8-1 (forward/longitudinal surge mechanics)

Ice removes the friction that would normally absorb a surging wave's force, so even a modest shift of liquid can translate into real vehicle movement. This combination of surge plus low traction is exactly why the tank endorsement knowledge test treats liquid surge as its own topic. Drivers who underestimate this pairing risk sliding into intersections or other vehicles.