Evaluation of Public Transportation System through Social Network Analysis Approach
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe study presents an evaluation of public transportation services through Social Network Analysis (SNA). The approach is used on real data to gain insights into the efficiency and effectiveness of bus transportation network in a Korean city.
· General comments
o Introduction and literature review: The introduction is comprehensive, and literature review is extensive (although I did not understand why you review AHP studies). However, it would be beneficial to also clearly state the research questions you are trying to answer, this can be for instance done by clearly mentioning the research gap in your literature review. Your hypotheses can also be stated at the end of the introduction to guide the reader. Also, it could help to summarize/give an overview of the reviewed studies/approaches as a table in your literature review section.
o Methodology: The methodology is sound, but more details on the data collection process, and how certain measures/degrees (centricity and betweenness) are calculated with passenger volumes. Also, unclear when/whether such degrees are standardized or not. This can improve the transparency and reproducibility of the study.
o Results and Discussion: The results section is detailed, but a clearer distinction between the presentation of results and their interpretation would make it more concise.
o Conclusions: The practical implications are mentioned but could be expanded, e.g., direct policy implications and/or decision-making recommendations. The limitations can be more explicit. Suggestion for future research could go beyond dealing with the study limitations, e.g., further applications or theoretical developments.
o Language: Ensure consistent use of terms throughout the manuscript. Some sentences are long/complex, consider breaking them into shorter statements. Also, some minor grammatical errors, a thorough proofread is recommended. Below some more specific comments.
· More specific comments
o Line 16: You mention that connectivity within the PT network is overlooked in the literature. However, this is not highlighted in your literature review.
o Lines 17-19: Sentence is long and/or difficult to understand. Could be divided into several sentences.
o Line 32: You mention that increasing the use of PT is proposed as an effective solution. You could include a reference to support this, but I would say that shifting from polluting means of transportation, e.g., electrification, shared mobility, etc.
o Lines 46-48: This sentence is also long and/or difficult to understand. Formulate in shorter sentences.
o Lines 53-56: … in the region. Which region? This paragraph is very generic and should be rewritten.
o Line 61: To determine the importanT weights
o Line 136: … commuteR networks using SNA. Also which networks, bus/rail?
o Lines 178-181: You could give examples of structural regulations, mathematical concepts, the fields where SNA gained attention.
o Line 186: first sentence is confusing.
o Lines 192-195: You define/formulate degree centrality based on route, but could be helpful to describe the differences (if any) based on passenger volume.
o Line 194: The mathematical formula or formulation (not formular).
o Line 200: total number of nodes g. Otherwise, no mention of g in your text!
o Equation 2: use division as in equation 3 instead of ÷symbol
o Line 201: no need for “as follows”.
o Equation (4) following (3), not (3) again
o Equation (4), what is C_g, I guess you mean C_B you defined in equation (3).
o No need for “of” in max of in equation (4)
o Figure 1, it is important to mention that node B is our subject node or what you call in line 221 as the node responsible for the broker role.
o In the description of the types of brokerage relations, it would be nice to have examples from the context of public transportation, as it is needed to understand your results later.
o Line 250, mention that inference methods can be used, include a reference, e.g., to https://doi.org/10.1007/s12469-021-00282-0
o Figure 3: It also includes the population density from figure 2. Mention that in the caption.
o Figure 4: What are the bubbles and their different sizes. Include in the caption.
o Table 1: Top …. Transfer VolumE
o Header of second column in table 1, boarding
o Table 1 is better as a figure, e.g., bar chart (stations at x-axis, two y-axis).
o Line 328: I would help to (previously) explain how average degree centrality is calculated based on passenger volumes.
o Line 333: no need for “sizes of ”
o Line 344: high degree centrality in each network. Are you talking about standardized value that was previously presented in equation 2 and 4. It is a bit confusing here.
o Figure 5: include in the caption the meaning of the brown dots, bubbles. Also mention the population density in red.
o Same for figure 6.
o Line 398: it would be good to previously explain how this brokerage score is calculated.
o Line 490: Where are the bus stop located for route M4137, a geographical visualization, e.g., with population density, would be useful.
o Line 542: result obtained, .. no s
o Line 612: SAN, you mean SNA.
Comments on the Quality of English LanguageThe quality of the English language is generally good but can be improved for better readability and clarity. Some sentences and paragraphs are overly long and complex. Breaking them into shorter, more concise statements can improve comprehension. There are some minor grammatical errors and awkward/long/unclear phrasings throughout the paper. A thorough proofread is recommended.
Author Response
Thank you very much for taking the time to review our manuscript and for providing such valuable feedback. We greatly appreciate your meticulous evaluation, which has significantly contributed to the improvement of our paper.
We have carefully considered and addressed all the points you raised. A detailed response to your comments has been prepared and is attached in a document for your review.
Please see the attachment
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsDear Authors,
I am very grateful for the opportunity to review your manuscript that evaluates the public transportation system through a social network analysis approach.
According to the research approach explained in the manuscript, the study aims to deepen empirical to the public transportation system, focusing on bus stop locations and route networks in Hwaseong City, South Korea.
As explained below, some aspects of your research approach are unclear and should be slightly improved to better meet readers' expectations, thus satisfying the high demands of the journal Sustainability (ISSN 2071-1050). I strongly recommend carefully reading the author’s instructions from the journal webpage.
#Abstract:
Please be aware that all words reflected in keywords must be previously quoted from the abstract in order of appearance. For instance, the terms “brokerage” and “centrality” should have not explicitly been written in the abstract since these have been used as keywords. Please check it and correct this as soon as possible.
#Introduction:
This part is a bit short and does not help readers understand the whole framework of the research approach that should meet the scope of the journal. I urge you to expand it for a better explanation of the scope of your study, particularly those aspects of your approach that have relevance to managing vehicles with non-fueled internal combustion engines used in public transportation in terms of sustainability.
There is also a lack of research questions that should have been introduced in such a key subpart of the manuscript.
#Literature Review
I recommend to use of tables, since a summarized selection of previous works on a table is always very valuable for readers, particularly in the case of approaches very specific in the field of the public transportation sector, and of those changing in terms of sustainability.
Furthermore, for the sake of better presentation thereof, both quantitatively and qualitatively, the literature review should be shown in a table, besides the valuable explanation shown in this subpart. Nevertheless, the reference list at the end of the manuscript is a bit scarce. Therefore, I recommend you expand the reference list by including only articles from prestigious journals.
#Results
Regarding Figure 1, you should have indicated its source. That is, you must write “Source: Own elaboration / Own elaboration based on [referred to the main source, if applicable]”, or something like that. The same applies to all other figures and tables shown in the manuscript (e.g. Figures 2-11; Tables 1-2).
#Study Area
This subpart is good. Particularly commendable is the creation of visualizations from Figure 2-11. However, this should be well-displayed for a better appearance. For instance, the background does not help for a friendly reading.
Concerning Figure 2, apart from indicating the source, even if it is your own, the software (and version) for such a nice graphical view should be here noted. The same applies to all other figures from the manuscript (Figures 3-11).
#Evaluation of the Public Transportation Network
No significant objection.
Line 321: The acronym “COVID-19” should be defined for the first time. That is, the term “COVID-19” should be replaced by the words “Coronavirus disease 2019 (COVID-19)”. The same applies to all acronyms in your paper.
#Aplication
No objection.
# Conclusions
Although the research has been strictly consigned to the domain of the domestic sphere of Hwaseong City, South Korea, the author should be able to identify possible similarities with findings collected in previous investigations within the public transportation sector from other cities abroad.
Finally, I suggest that a specific section should be devoted to explaining your research recommendations for future studies. In addition, I recommend you summarize the research restrictions based on those constraints related to the study by using a bulleted list.
Best regards,
The Reviewer.
Comments on the Quality of English Language
Minor editing of the English language is required. Please check it before submitting the improved version for a second review.
Author Response
We sincerely thank you for your meticulous review of our paper. Your insightful comments have been invaluable, and we have diligently incorporated your suggestions to enhance the quality of our manuscript.
We have responded to each of your suggestions in detail, and you will find a comprehensive reply attached in the document.
Please see the attachment
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThis is a nice academic exercise. It uses some approaches of social network analysis, particularly centrality indices, for characterizing the existing bus network in a South Korean city.
The objectives defined in the introduction (improving efficiency and effectiveness of PT services, ultimately contributing to environmental sustainability and enhanced mobility ...) are not achieved. Beneficial links to the optimal planning of bus systems cannot be discovered. Many conclusions are trivial (e.g. in section 7.1: characteristics of bus stops, bus stop at the center of a group defined as "coordinator", at the boundary of a group defined as "representative" or "gatekeeper".
Some details:
(1) Route-based degree centrality is correctly defined by equation (1). What about passenger volume-based (standardized) degree and betweenness centrality?
(2) Because of missing clear definitions the reader cannot evaluate the numerical results.
(3) There is still a high number of typos.
Author Response
Thank you for taking the time to thoroughly review our manuscript. Your constructive feedback has been instrumental in refining our work, and we have carefully integrated your suggestions to strengthen our paper.
We have addressed all of your comments with care, and a detailed response document has been attached for your consideration.
Please see the attachment
Author Response File: Author Response.pdf
