## 4 Conclusions  
This paper introduces the use of a vehicle in a stationary position to detect bridge damage. The proposed damage detection methodology is not based on a healthy bridge response baseline; therefore, it can detect damage without relying on prior information of the bridge. The method consists of three steps, which start by computing the contact-point response of the stationary vehicle, then decomposing the obtained response using VMD into narrow-banded IMFs, and finally, computing the IA of the high frequency IMF. While road roughness is considered, the method is examined under different conditions on a bridge of 25 m. The proposed method was implemented on bridge damage, considering several conditions such as the followings:  
* Considering damage of 1 m in length (from 7.5 to 8.5 m away from the bridge beginning), zero damping of stationary vehicle located at mid-span, and speed of a moving vehicle of 12.5 m/s, the proposed method was able to detect the location of the damage accurately. When the location of the stationary vehicle was moved further away from the damage (20 m away from the bridge beginning), the IA also could show the peak at the correct location of the damage. After identifying the damage location from two positions of the stationary vehicle, the vehicle was stationed at the damage to investigate the response of the vehicle. In this case, only one peak of the IA appeared, and its amplitude was higher than that of the previous cases.
* When the IA of healthy and damaged bridge were compared, the irregularities at the bridge boundary remained similar; however, the peak that represents damage in the damaged bridge did not appear in the healthy bridge IA result. Irregularities at the boundaries do not represent damage and they occur due to the boundary condition of the bridge. Therefore, the method cannot detect damage near the boundaries of the bridge.
* When multiple damage was considered by adding another damage of 1 m (from 18.5 to 19.5 m) to the bridge, the proposed method could also detect the damage. Therefore, by considering the added mass of the stationary vehicle as a damage, the method could detect up to three points of damage on the bridge.
* When damping of 0.05 was added to the stationary vehicle, the vehicle was still able to detect the damage, but with less visibility. In addition, when the length of the single damage case was reduced to 0.5 m (from 8 to 8.5 m), the method could still detect the smaller damage, but with a lower visibility. Finally, when the speed of the moving vehicle was reduced to 5 m/s, lower visibility in the peak of IA was noticed.  
Figure 12: IA of IMF of the contact-point response of a stationary vehicle with 5 m/s speed of the moving vehicle.  
**Author Contributions:** Conceptualization, I.H & E.N.; Investigation, I.H.; Methodology, I.H.; Supervision, E.N.; Writing--original draft, I.H. All authors have read and agreed to the published version of the manuscript.  
This research was funded by Universiti Teknologi PETRONAS Malaysia under grant number YVTP 015 LC0-177.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Acknowledgments:** The authors wish to acknowledge the financial support received from the Universiti Teknologi PETRONAS Malaysia.  
**Conflicts of Interest:** The authors declare no conflict of interest.