Research on the Prediction Model of the Friction Coefficient of Asphalt Pavement Based on Tire-Pavement Coupling

Table 5

Levels of the variables of the orthogonal test.

Item	Level 1	Level 2	Level 3
Macrotexture (mm)	(A1) 0.46	(A2) 1.29	(A3) 1.41
Tire load (N)	(B1) 150	(B2) 200	(B3) 250
Tire pressure (bar)	(C1) 2	(C2) 2.5	(C3) 3
Tire speed (km/h)	(D1) 10	(D2) 20	(D3) 30
Microtexture (-)	(E1) 0.320	(E2) 0.411	(E3) 0.428