Multilevel Approach for Management of Existing Bridges: Critical Analysis and Application of the Italian Guidelines with the New Operating Instructions
Round 1
Reviewer 1 Report
This paper provides an application case by Italian Guidelines and Operating Instructions in Italy based on a large sample of the procedures for the classification of existing bridges. It is a meaningful topic for the bridge management and maintenance. There are some problems to be discussed including the followings:
1. In Table 1, is the summary about the primary parameters and secondary parameters for the three levels of Hazard, Vulnerability and Exposure comprehensive? In addition, what is the basis for determining the primary and secondary parameters?
2. Is the method described by the authors in Sections 2 and 3 included in Guidelines and the Operating Instructions in Italy? Are these methods proposed by the authors?
3. How do you determine the number of structures at different levels (low to medium-low, medium, medium-high to high) in Figures 9 and 10? Are them related to structural types and structural components? How do you describe these relationships qualitatively or quantitatively?
4. How to classify the structure as a whole considering the correlation between the performance degradation of each structural member?
5. How to detect and evaluate the bridge components? What needs to be recorded? When evaluating the overall performance, how to get the weight of each component?
6. The calculation process for the number of structures at various levels given in Figures 11-14 is not clear. In addition, how to consider the weights of Hazard, Vulnerability and Exposure when calculating the warning class?
7. In Section 4, only the vulnerability class is given. What about the class results of other factors such as Hazard class, Exposure class?
8. Is the method in this paper applicable to all types of bridge structures? When calculating the vulnerability class, are the primary and secondary parameters for different types of bridges consistent?
Author Response
Dear Reviewer,
The Authors provided answers to your relevant comments and suggestions in the attached file.
Thank you very much for the work done, that really increased the quality of the paper.
Our best regards
The Authors
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The study concerns the strcuctural safety management of existing bridges in Italy according to the recently developed guidelines on the topic. First, an extended description of the framework introduced by the abovementioned regulation is reported. In the second part of the study, the authors present the results of the classification framework applied to 661 bridges in Italy. Particularly, the authors discuss the distribution of the analysed bridges with reference to the period of construction, the level of defectiveness and the associated vulnerability class. According to this reviewer, the study is clear, and well-written and provides interesting outcomes with reference to the topic of the safety management of existing bridges. Several (minor) comments to be addressed for considering the study suitable for publication in the Journal are provided below.
1. The first part provides a refined critical description of the framework for calculating the hazard, vulnerability and exposure classes leading to the final warning class. Therefore, in this reviewer’s opinion, an additional subsection including the process for the calculation of the final warning class based on hazard, vulnerability and exposure classes should be reported.
2. To foster clarity, this reviewer suggests moving the discussion from L298 to L316, on the influence of vulnerability and hazard classes on prioritisation, at the end of Section 3, possibly after presenting the process for calculating the warning class. Indeed, in this reviewer’s opinion, it could be hard for a reader (not knowing the contents of the guidelines) to understand how vulnerability can be used for prioritisation before this is introduced in the text by the author.
3. Further information on the comparisons reported in Figure 7 should be provided. For example, geometric data (e.g. span length) on the case-study adopted to perform the presented calculations are needed.
4. The authors should introduce information on the geographical distribution of the case-study bridges adopted for the final critical analysis.
Author Response
Dear Reviewer,
The Authors provided answers to your relevant comments and suggestions in the attached file.
Thank you very much for the work done, that really increased the quality of the paper.
Our best regards
The Authors
Author Response File: 
Author Response.docx
Round 2
Reviewer 1 Report
The author has improved the manuscript and answered all questions, so I recommend accepting this paper for publication.
