Table 1 The data variables.
Variables | Description | Variable type |
|---|---|---|
Structure and material data | ||
 Thickness of surface layers | Sum of thickness of upper, middle, and lower surface layers in Fig. 1 | Numerical |
 Materials of base courses | Mixtures of cement, lime, industrial waste, or asphalt with soil or gravel | Categorical |
Traffic volume data | ||
 AADTT | Average annual daily truck traffic | Numerical |
 AADT | Average annual daily traffic | Numerical |
Climate and environmental data | ||
 Total high temperature days | Total number of days with daily average temperature > 25 ℃ in a year | Numerical |
 Number of consecutive high temperature | Number of consecutive 3 days or more with daily average temperature > 25 ℃ in a year | Numerical |
 Total low temperature days | Total number of days with daily average temperature < 0 ℃ in a year | Numerical |
 Number of consecutive low temperature | Number of consecutive 3 days or more with daily average temperature < 0 ℃ in a year | Numerical |
Pavement condition data | ||
 PCI of previous year | PCI: Pavement surface condition index, with values ranging from 0 to 100, where 0 indicates the worst pavement condition and 100 indicates the best pavement condition | Numerical |
 PCI of current year | Numerical | |
Other data | ||
 Road age | Current year—year of road completion | Numerical |
