## 2 Cost Components
### Road User Cost  
#### 2.2.1 Normal Operating User Costs  
This refers to user costs during normal highway operations (non-work zone). It has a direct relationship with pavement performance. For each candidate preventive maintenance schedule, this cost can be estimated using the following models: Each preventive maintenance schedule has its own associated expected performance model (level of condition at each year of the schedule). Then, using cost-condition models, the user cost associated with each preventive maintenance schedule can be determined. (1) Vehicle Operating Costs  
Vehicle operating costs mainly include fuel consumption during driving, tire wear, and maintenance material consumption. 1 Fuel consumption cost  
Fuel consumption is the cost generated by the consumption of power energy during the driving process of the vehicle. The vehicle fuel consumption cost of the road section is calculated by Formula (3) [22]:  
\[\text{FCC}=\text{Q}\cdot\text{FC}/100\cdot\text{P}_{\text{F}}\cdot\text{1} \tag{3}\]  
where  
FCC--vehicle fuel consumption cost of the road section (yuan)  
Q--traffic volume of the road section (vehicle/y)  
P\({}_{\text{F}}\)--unit price of fuel oil (yuan/L); the current reference price of gasoline is 7.16 yuan/L; and the price of diesel oil is 6.76 yuan/L  
1--the section distance (km),FC--unit vehicle fuel consumption (L/100 km); the calculation formulas of fuel consumption, vehicle speed, and IRI of different models are shown in Table 2:  
2 Tire Wear-and-Tear Cost  
Tire wear and tear cost refers to the depreciation cost of tires caused by the continuous wear and tear of surface materials caused by mechanical and chemical reactions during the relative movement of tires and road surfaces during the vehicle's operation [24]. The tire consumption cost of vehicles on the road section is calculated using the following formula [22]:  
\[\text{WC}=\text{Q}\cdot\text{W}/1000\cdot\text{P}_{\text{T}}\text{-I} \tag{4}\]  
where  
WC--vehicle tire consumption cost of the road section (yuan)  
P\({}_{\text{T}}\)--Tire unit price (yuan/piece), as shown in Table 3.  
W--Tire loss per unit vehicle (per 1000 km) The calculation formula for tire consumption and IRI of different vehicle models is shown in (5) [19]:  
\[\text{W}=\text{a}_{0}+\text{a}_{1}\cdot\text{IRI} \tag{5}\]  
where  
\(\text{a}_{0}\), \(\text{a}_{1}\) is the regression coefficient [21], and the regression coefficients for different vehicle models are shown in Table 4.  
3 Repair and Maintenance Cost  
The vehicle repair and maintenance costs mainly involve labor costs and material consumption costs during the repair process. The vehicle repair and maintenance cost for the road section is calculated using the following formula [22]:  
\[\text{RC}=\text{Q}\cdot\text{R}/1000\cdot\text{P}_{\text{R}}\text{-I} \tag{6}\]  
where \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Regression** & **Passenger Car** & **Bus** & **Small Truck** & **Big Truck** \\
**Coefficient** & & & & \\ \hline \(\alpha_{0}(10^{-2})\) & 4.66 & 7.39 & 6.99 & 15.56 \\ \(\alpha_{1}(10^{-3})\) & 7.1 & 1.6 & 10.7 & 3.4 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Regression coefficients of the relationship between tire consumption and IRI. \begin{table}
\begin{tabular}{c c} \hline \hline
**Vehicle Type** & **Relationship Model** \\ \hline passenger car & \(\text{FC}=-0.21637\times\text{V}+0.0013055\times\text{V}^{2}+0.24808\times \text{IRI}+15.36580\) \\ bus & \(\text{FC}=-1.07275\times\text{V}+0.0084534\times\text{V}^{2}+1.12121\times \text{IRI}+43.00515\) \\ small truck & \(\text{FC}=-0.56612\times\text{V}+0.0040141\times\text{V}^{2}+0.56222\times \text{IRI}+25.29872\) \\ big truck & \(\text{FC}=-1.64706\times\text{V}+0.014388\times\text{V}^{2}+1.5899\times \text{IRI}+62.90253\) \\ \hline \hline \end{tabular} where V—the vehicle speed (km/h). IRI—International Roughness Index, m/km.  
\end{table} 
Table 2: The relationship between fuel consumption, speed, and IRI [23].