This paper describes the results of experiments that were carried out with more than 50 non-professional drivers making acceleration, deceleration and lane change manoeuvres on ice at speeds where skidding was expected. The subjects drove their own car and four reference cars (Volvo 440 or 740) with front or rear wheel drive, and with differently studded tyres. In a combined braking and smooth lane change manoeuvre, the anti-lock braking system (ABS) increased the average deceleration significantly. Steerability and stability were also superior with ABS: lane marks hit in one of 208 tests compared to 30 of 208 tests without ABS. Deceleration was 20% greater with fully studded tyres than with basic studding on all wheels. In a non-braking but more severe double lane change manoeuvre, Loss-of Control (LoC) occurred in 40% of the tests with oversteering properties, induced by front biasing stud protrusion and number. If front and rear tyres were switched to understeering, less than 20% of the tests resulted in LoC. With all tyres fully studded, front driven cars had 30% LoC. Still, the larger cars were superior in manoeuvre severity quantities. The correlation of these quantities to LoC relative frequency was not confirmed by this study.
Samenvatting