# A Review and Future Directions on the Deterioration Evaluation of Concrete Utility Poles
## 5 Issues for Concrete Utility Pole Maintenance
### Issues for the Deterioration Evaluation of Concrete Utility Poles  
Previous studies on the deterioration evaluation of concrete utility poles found that, partly [30; 31; 32; 33; 34; 35; 36] due to the widespread use of wooden utility poles worldwide, concrete poles have not been sufficiently studied as research subjects. It is crucial to begin by accumulating the necessary data for the deterioration evaluation of concrete utility poles.  
For the correlation between non-destructive testing data and mechanical damage required for deterioration evaluation, previous studies have addressed aspects such as seismic performance [21; 22; 26] and the analysis of failure mechanisms in collapse cases [24]. Understanding the mechanical properties of utility poles is essential to improve maintenance efficiency. However, from the maintenance perspective, it is important to grasp the mechanisms of deterioration in actual service poles and the threshold of deterioration levels at which replacement becomes necessary. These aspects, however, have not been covered in the existing research on concrete utility poles. Therefore, future studies on the deterioration evaluation of concrete utility poles should focus on organizing the mechanisms of mechanical damage and fracture progression in service poles and defining the ultimate state and damage conditions that necessitate replacement.  
Existing studies on the deterioration evaluation of concrete utility poles using non-destructive testing methods are limited but have addressed advancements in vibration [30; 31], visual inspections [35; 36], and the evaluation of rebar deterioration using electromagnetics [32; 33; 34]. Although non-destructive testing results allow for detecting damage in utility poles, it remains challenging to determine whether the pole is safe in its current state or requires repair. Further data collection is necessary to evaluate the degree of deterioration in utility poles. This difficulty arises partly because the mechanical properties  
Figure 11: Image of density measurements at the base of the poles [82].  
of utility poles have not been sufficiently organized, making it challenging to define the degree of deterioration based on data obtained through non-destructive testing. To enhance the efficiency of utility pole maintenance, it is also important to organize the correlation between changes in the mechanical properties of poles and changes in measurement data obtained through non-destructive testing.  
Previous literature has also discussed challenges related to deterioration evaluation methods using non-destructive testing for wooden utility poles. [PERSON] et al. [47] reviewed the current state and challenges of non-destructive evaluation methods implemented to efficiently maintain wooden utility poles in Australia. They highlighted the need for more quantitative methods or data collection to calculate the remaining load capacity of utility poles, a challenge common to wooden utility poles. In the future, it is important to check the simulations against experiments using actual poles.  
Based on the above, previous studies on the maintenance of concrete utility poles have not sufficiently addressed damage progression over long-term service nor the correlation between non-destructive testing results and damage progression. The accumulation of further data is necessary for future research.