## 7 Results and Discussion
Additionally, hyperbolic shapes are not only associated with rebar in RC; thus, relying on templates can lead to false positives due to various hyperbolic shapes in the concrete. The algorithm developed in this study utilizes typical amplitude patterns of electromagnetic wave reflections from rebar, effectively reducing the likelihood of assigning random hyperbolic shapes in the RC as rebar. After validating the accuracy of manual data through automatic rebar detection, the research focused on analyzing the impact of different transverse and longitudinal GPR scan line offsets on the results. The core objective was to determine whether reducing the number of scan lines during data collection still provides comprehensive insight into the inner characteristics of reinforced concrete structures, such as rebar configuration and potential deficiencies. By minimizing data collection points while maintaining the reliability of profile data, this approach will enhance both the efficiency and accuracy of bridge inspections using GPR technology. Figure 11 illustrates the comparison of rebar depth for transverse profile spacings ranging from 4 in. to 24 in., while Figure 12 shows the comparison for rebar spacing. The results are summarized in Tables 2 and 3. Discrepancies between the calculated values and the information provided in Figure 2 were found to be associated with construction flaws, as the GPR device was specifically calibrated for the concrete box beam discussed in this paper and due to the consistency among different profile lines. Figure 10: Auto rebar picking for stirrups (longitudinal profile no. 3). Figure 11: Top reinforcement row depth: (**a**) Rebar #1; (**b**) Rebar #2; (**c**) Rebar #3; and (**d**) Rebar #4. Figure 12: Top reinforcement row spacing: **(a)** Space #1, **(b)** Space #2; and **(c)** Space #3. Figures 11 and 12 demonstrate that all transverse profile offsets show nearly identical rebar spacing and depth patterns for the structure. The average calculated values in Table 2 are nearly the same for all profile line offsets, with minimal variation. Table 3 shows the minimum and maximum calculated values for the rebar depth, horizontal concrete cover, and spacing among the transverse profile offsets ranging from 4 in. to 24 in. The consistency between the results suggests that different transverse profile line offsets have a minimal effect on the accuracy of the depth and spacing measurements of the top longitudinal reinforcement. Similar to the top transverse profile offsets, the effects of different spacing on GPR data collection for the longitudinal profile lines were also analyzed. In comparing one profile line versus three profile lines in the top longitudinal scans, no significant difference was found. The original plans indicated that the concrete box beam under study contains 41 stirrups, while the analysis of the GPR data identified 34 stirrups. The variation in the number of stirrups can be attributed to closely spaced shear reinforcement at both ends of the beam, making it difficult to accurately read the rebars due to the high electromagnetic conductivity in the area. Consequently, the precise number of stirrups could not be determined. However, the longitudinal profile image indicates a greater concentration of shear reinforcement at the end of the beam, which aligns with the typical characteristics of prestressed concrete box beams. Results for one and three longitudinal profile lines along the top face of the beam are summarized in Table 4. Maximum and minimum values calculated for the depth and spacing of the stirrups are shown in Table 5. While there is no significant difference between using one or three profile lines to ascertain shear reinforcement information, using only one longitudinal profile line could lead to the loss of valuable internal information. For example, with a single profile line running along the center of the beam, the internal voids of the