# Enhancing Reliability Analysis with Multisource Data:
## 3 Results Attained by Using the Proposed WIM and NBI Synthesis Method
### Reliability Analysis of Bridges in Georgia  
A reliability analysis for 655 bridges along the major routes are conducted with truck traffic, which includes class 4 or greater vehicles. As shown in Figure 4, bridges on major inter-state routes are associated with a WIM site based on the geographic information system (GIS) coordinates obtained from the NBI database [12]. Figure 5 shows a histogram representing gross vehicle weight (GVW) distribution for site 0210378 with a reference resistance distribution. A plot representing distributions of 235 bridge load capacities is also shown in Figure 6 for each bridge that is located along the routes shown in Figure 4.  
In Figure 6, the thin dashed gray line shows the capacity of a group of bridges reported in 2021, and the thin solid black line shows the capacity when the bridge was initially constructed. The purpose of this plot is to show the reduction (or increase) in load carrying capacities over time. The blue solid (thick) line shows the live load on a bridge observed in the WIM data, and the red dashed (thick) line shows the bridge capacity when a reliability index of 2.5 is selected for the live load distribution observed in the WIM data. The Reliability Index (RI), along with the probability of failure, is calculated for each bridge using Equations (2) and (3). As shown in Figure 4, a significant fraction of bridges have a RI less than 2.0, which means that the results require a review of either the operating load ratings or the vehicle weight data available in the WIM systems.  
Figure 4: Map showing locations of old and reconstructed bridges in Georgia.  
Figure 5: WIM live load histogram fitted with normal distribution and NBI OR distribution.  
To observe the change in RI over time, coupled stacked bar charts are created for different routes shown in Figure 7. The x-axis represents the year in which the WIM data were observed at multiple WIM sites. The y-axis represents the percentage of bridges with RIs in three different categories when analyzed with the associated WIM site data. The white stack represents the percentage of bridges with a RI less than 2.0, the gray stack represents the percentage of bridges with a RI greater than or equal to 2.0 and less than 5.0, and the black stack represents the percentage of bridges with a RI greater than or equal to 5.0. Additionally, to observe the relationship between the time of construction and bridge capacities, Figure 8 is created.  
Figure 6: Load and capacity curve of bridges (Site ID: 0210378).  
Figure 7: Bridge reliability in percentage for routes (**a**) I-75, (**b**) I-95, (**c**) I-16, and (**d**) I-20.  
The design vehicle used in this study is a HL-93 truck, which has a GVW of 80 kips (355.86 kN) as indicated as a horizontal line in Figure 8. Some bridges at WIM site 0210378 on the I-75 route have a capacity less than 80 kips (355.86 kN) and were constructed before 1980. Some bridges have a capacity as low as 50 kips (222.41 kN) even after reconstruction. In Figure 9, bridges with a low reliability (RI \(<\) 2.0) are presented by age groups in each route.  
Notably, most of the bridges with a low RI are 40 years old or older, which attests to the use of operating LR for evaluating load carrying capacities and respective reliability indices. As anticipated, RI and bridge age are highly correlated.  
Figure 8: Operating rating vs. year built/reconstructed (Note: 1 kip = 4.4482 kN).  
Figure 9: Histogram Showing the Number of Low Reliability (RI \(\leq\) 2.0) Bridges by Age Groups in Routes (**a**) I-75, (**b**) I-95, (**c**) I-16, and (**d**) I-20.