# A Review and Future Directions on the Deterioration Evaluation of Concrete Utility Poles
## 4 The Current Studies of Wood Utility Pole
### Deterioration Evaluation of Wood Utility Pole
Another probabilistic approach is assessing the degree of damage from the poles' visible tilting (deformation). [PERSON] et al. [75,76] have developed a method to estimate the probability of failure when tilted poles are loaded with wind pressure, overturning forces, and conductor tension on the wires. The method has been trialed in a case study concerning parts of Houston, Texas. The proposed method benefits practitioners by facilitating effective risk-informed decision-making to prioritize maintenance tasks over many leaning poles in the distribution infrastructure system before the hurricane season and is effective in increasing community resilience to cascading power outages. Simulation methods generally involve creating a three-dimensional model, assigning variables such as wind speed and pole dimensions to the model, calculating the probability of destruction of utility poles, and applying the results to replacement evaluations. However, as dynamic studies of actual wood poles are not well organized, it is anticipated that it may be essential to evaluate the structural performance of wooden poles in combination with an assessment, such as their end state. To reduce the risk of collapsing old poles, approximately 300,000 poles are replaced every year in the eastern states of Australia, and it has been observed that up to 80% of the poles replaced are still in excellent condition [51], so dynamic evaluation is also considered important from the perspective of cost reduction. Other non-destructive evaluation studies of utility poles have been carried out in addition to the abovementioned methods. Research has also been conducted to improve the visual assessment of external appearance by matching it with the above-mentioned probabilistic simulation and using UAVs to improve the efficiency of visual inspections [78, 79, 80, 81, 82, 83]. For example, [PERSON]. et al. [78] proposed a method to assess the probability of pole failure by utilizing 2D images of poles taken by a drone and estimating the inclination of the pole in the image. [PERSON] et al. [79,80] propose a method for estimating the strength of utility poles using machine learning from the collapse of poles obtained from images of the poles taken by drones. The loads considered in this study should be limited to wind and gravity. Future issues are also discussed, such as the importance of soil conditions and the aging of materials, which need to be considered in the future. As mentioned above, various studies are being conducted, such as using drones and other equipment to take images and machine learning to improve the efficiency of visual observation, and applying the estimation mentioned above of failure probability to wooden utility poles to estimate strength from the images obtained. [PERSON] et al. [82] summarize the existing research on the advancement of visual inspection of power transmission and distribution facilities and state that, until now, the inspection of power transmission and distribution facilities has generally been carried out manually or by helicopter. Still, in recent years, the use of drones, automatic helicopters, robots, etc., has been investigated. The current issues regarding the advancement of image diagnosis include the lack of image data on damaged equipment, the inability to detect even internal damage, and the difficulty of detecting minute parts. For other methods, [PERSON] [83] proposed a nondestructive evaluation method for wooden utility poles based on the compressive strength and moisture content converted from the density measurement of the wood near the ground surface of the pole shown in Figure 6.0 The study confirmed a correlation between the strength estimated from the density and the strength of wooden utility poles.