# Life-Cycle Cost Analysis on Application of Asphalt and Concrete Pavement Overlay
## 3 Analysis and Results
### User Cost
#### 3.1.2 Analysis of User Cost According to the Number of Lanes  
The AADT of two- and four-lane expressways was examined and applied, and the method of completely blocking one lane was applied. The user cost according to whether the shoulder was used or not was analyzed under the construction of asphalt and concrete overlays by applying the appropriate road-blocking period, as shown in Table 1. For asphalt overlay, 2 days/km for cutting and cleaning, 1 day/km for asphalt laying, and 8 h (22:00-06:00) for curing were applied. For concrete overlay, 2 days/km for cutting and cleaning, 2 days/km for concrete laying, and 3 days for curing were applied. With respect to the variables for the analysis of the user cost, the vehicle speed before construction, based on two lanes, was assumed to be 100 km/h; the vehicle speed in one lane was assumed to be 60 km/h; and during the complete blocking of one lane, the detour rate was considered as 10%, as shown in Table 1. In four lanes, the vehicle speed before construction was assumed to be 100 km/h; the vehicle speed in three lanes was assumed to be 60 km/h; and during the blocking of one lane, the detour rate was considered as 10%. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Method**} & \multicolumn{3}{c}{**Non-Reimbursable**} & \multicolumn{3}{c}{**Remuneration**} \\ \cline{2-7}  & **Number of Lanes** & **Speed** & **Number of Lanes** & **Speed** & **Blocking Day** & **Bypass Rate** & \\ \hline Asphalt & 2 lanes & 2 & 2 & 2 lanes & 1 & 60 km/h & 1 km road/3 days + 8 h & 10\% \\ Overlay & 4 lanes & 4 & 100 km/h & 2 lanes & 1 & 60 km/h & 1 km road/5 days & 10\% \\ \hline Concrete & 2 lanes & 2 & 2 & 2 lanes & 1 & 60 km/h & 1 km road/5 days & 10\% \\ Overlay & 4 lanes & 4 & 100 km/h & 4 lanes & 3 & 60 km/h & 1 km road/5 days & 10\% \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Variables applied to user cost (complete blocking). Figure 1: Relationship between traffic volume and user cost maintenance. Case 1--User cost under the application of overlay for two lanes: The traffic volume of two-lane expressways was identified by examining the pavement management system (PMS) data. For the identified traffic volume ranging from 4000 to 11,000 AADT, 6000 and 11,000 AADT were applied for analysis. 2. Case 2--User cost under the application of overlay for four lanes: The traffic volume of four-lane expressways was identified by examining the PMS data. For the identified traffic volume ranging from 15,000 to 35,000 AADT, 15,000, 25,000, and 35,000 AADT were applied for the analysis. In case 1, Figure 2 shows the user cost analyzed under the traffic volume of 6000 AADT. The user cost of asphalt and concrete overlay tended to increase as the length increased. The user cost of concrete overlay, however, increased more rapidly than that of asphalt overlay as the length increased. Compared to the user cost for the minimum repair length of 0.3 km, the user cost for the maximum length of 15.0 km increased by approximately 3970 and 3640% for concrete and asphalt overlays, respectively. Concrete overlay exhibited approximately 340% higher user cost than asphalt overlay. Figure 3 shows the user cost result of 11,000 AADT for two lanes. Figure 2: User cost comparison (Shoulder X, 6000 AADT). (**a**) Asphalt overlay user cost (Shoulder X). (**b**) Concrete overlay user cost (Shoulder X). (**c**) Comparison of overlay user cost (Shoulder X). The user cost for 6000 AADT tended to increase with increasing repair length, and the user cost increase rate of concrete overlay was higher than that of asphalt overlay. The user cost increase rate for a repair length of 15.0 km, compared to 0.3 km, was approximately 3970 and 3850% for concrete and asphalt overlays, respectively, indicating that the difference was approximately 116%. The difference in user cost increase rate, with respect to the minimum repair length, between asphalt and concrete overlays decreased as the traffic volume increased, despite the increase in user cost.