Analysis of Core Area Characteristics in Travel Networks Using Block Modeling

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Using traffic-based start-to-end (OD) data, this research analyzes regional travel patterns, network structure, and core areas in the South Korean capital region using block modeling techniques to help address the problem of over-concentration of resources. It is found that compared with passenger transport, freight transport has more frequent inter-regional activities and depends on long-distance transport. The core area of passenger transport is often the geographically central city, and the core area of freight transport is the surrounding city. It highlights the different characteristics of passenger and freight travel and provides insights for promoting balanced development.

1. Introduction section: this research emphasizes the need for policies that address this concentration and promote balanced regional development. On the basis of background combing, the corresponding research objectives are put forward. However, although a comprehensive review is carried out in the next section, it is hoped that some research review can be added before the research objectives are proposed.

2. Literature Review section: The literature review in this part is comprehensive and covers key studies related to travel patterns, urban networks, and regional development. However, on the whole, there is a lack of critical analysis for each part of relevant research and the research gap proposed on this basis, suggesting that the summary and comparative analysis of relevant literature should be strengthened.

3. Methodology section: it is well-described, with a clear explanation of the block modeling and eigenvector centrality analysis used to identify core areas and analyze travel patterns.  Meanwhile, the data sources are appropriate and relevant, including passenger and freight OD data from the Korea Transport Database.  It is suggested to add to this part. a rationale for the specific scales chosen for the analysis. At the same time, it is recommended to discuss any potential limitations of the data sources and selected methods.

4. Results & Discussion section: While the results are very comprehensive, the discussion could be enhanced by including a comparison with other studies or models to highlight the uniqueness or improvements of the current study.

Overall, it is recommended for publication with above minor revisions.

Author Response

Reviewer 1 Response Letter

1. Introduction section: this research emphasizes the need for policies that address this concentration and promote balanced regional development. On the basis of background combing, the corresponding research objectives are put forward. However, although a comprehensive review is carried out in the next section, it is hoped that some research review can be added before the research objectives are proposed.

Response: We sincerely appreciate your meticulous review and constructive feedback. Based on your suggestions, we have revised and enhanced the Introduction section as follows. First, prior to presenting the research objectives, we incorporated additional discussions on the issue of resource concentration in South Korea's Seoul Metropolitan Area and its profound implications for national and regional imbalances. By reviewing relevant studies and data, we underscored how the overconcentration in the capital region serves as a critical barrier to sustainable national development, thereby reinforcing the necessity for balanced regional development policies.

Furthermore, we analyzed the achievements and limitations of existing policies to provide a more compelling rationale for this study. Specifically, we highlighted that traditional policies have predominantly focused on fostering the independent growth of individual regions, often overlooking the potential synergies that could be generated through inter-regional cooperation and network strengthening. To address this gap, we emphasized the importance of adopting polycentric strategies that enhance functional linkages between regions, positioning this study as an effort to explore the feasibility of achieving balanced development through such approaches.

Additionally, in response to your recommendation, we clarified the research objectives and provided an outline of the paper’s structure at the end of the introduction. This addition aims to guide readers through the content and logical flow of the study, ensuring clarity and accessibility. We hope these revisions adequately address your valuable feedback and enhance the overall quality of the manuscript.

 

2. Literature Review section: The literature review in this part is comprehensive and covers key studies related to travel patterns, urban networks, and regional development. However, on the whole, there is a lack of critical analysis for each part of relevant research and the research gap proposed on this basis, suggesting that the summary and comparative analysis of relevant literature should be strengthened

Response: We sincerely appreciate your thorough review and insightful comments. In response to your observations regarding the insufficient critical analysis and identification of research gaps in the literature review, we have revised and enhanced this section of the manuscript as follows:

First, to strengthen the critical analysis of existing studies and clearly define the research gaps, we systematically summarized and compared studies related to passenger and freight travel characteristics, urban network analysis, and regional development. For instance, we discussed the influence of land use and transport network accessibility on travel patterns, as highlighted by Stead and Marshall (2001) and Headicar and Curtis (1994), identifying the limitation of these studies being largely passenger-centric. Additionally, while Giuliano and Narayan (2003) and Cervero (1996) examined the effects of urban form and socioeconomic factors on travel, we emphasized the lack of focus on freight travel dynamics in their analyses.

Second, in the domain of network analysis, we synthesized findings from Saberi et al. (2017), Burger et al. (2014), and Guo et al. (2023), which explored the polycentricity and functional integration of urban networks. However, we noted that these studies primarily focused on either passenger or freight networks, rather than integrating both. To address this gap, our study adopts a holistic approach by analyzing both passenger and freight networks concurrently, offering a comparative perspective on interconnections among core areas.

Lastly, to highlight the originality of this study, we have included a dedicated "Research Distinctiveness" section. This section underscores the scarcity of existing research that comprehensively analyzes the interplay between passenger and freight travel networks. It also clarifies our aim to compare these networks and contribute novel insights to the field of urban network research.

 

3. Methodology section: it is well-described, with a clear explanation of the block modeling and eigenvector centrality analysis used to identify core areas and analyze travel patterns.  Meanwhile, the data sources are appropriate and relevant, including passenger and freight OD data from the Korea Transport Database.  It is suggested to add to this part. a rationale for the specific scales chosen for the analysis. At the same time, it is recommended to discuss any potential limitations of the data sources and selected methods.

Response: Thank you for your detailed and insightful feedback on the methodology section. Based on your suggestions, we have revised and enhanced the methodology as follows:

 

Justification for the Selection of Analytical Scale
The study divides South Korea into five regions—Seoul Metropolitan Area, Chungcheong, Gangwon, Jeolla, and Gyeongsang—based on administrative boundaries while reflecting regional geographic linkages and unique travel patterns. For instance, the Seoul Metropolitan Area is characterized by high population density and a complex transportation network, whereas Jeolla and Gyeongsang exhibit distinct industrial structures and logistics flows. The temporal scope is set to 2020, as it represents the most recent data available, allowing for an accurate reflection of regional characteristics. These adjustments enhance the validity of our analysis by providing clear justifications for the spatial and temporal frameworks.

 

Clarification of Data Sources and Software Utilization
We utilized passenger and freight OD data provided by the National Transport Database Center, a crucial resource for analyzing inter-regional mobility and connectivity. The analyses employed Netminer 4 for block modeling and eigenvector centrality, leveraging its network analysis specialization. Additionally, SPSS 26 was used for multiple regression analyses to ensure statistical reliability. These revisions include explicit explanations of data sources and analytical tools, emphasizing the reliability of the methodology.

 

Acknowledgment of Limitations and Mitigation Strategies
The study explicitly addresses potential limitations, such as OD data’s inability to fully capture movements during specific timeframes or informal routes. To mitigate these issues, we supplemented the network analysis with additional observations of actual interaction patterns, enhancing the generalizability of the results. Furthermore, the limitations of block modeling and eigenvector centrality were addressed by integrating multiple regression analyses, thereby improving the robustness and credibility of the findings.

 

These refinements ensure a more comprehensive and transparent methodology, aligning with the reviewer’s recommendations.

 

4. Results & Discussion section: While the results are very comprehensive, the discussion could be enhanced by including a comparison with other studies or models to highlight the uniqueness or improvements of the current study.

Response: Thank you for your insightful and constructive comments on the discussion and conclusion sections. Your feedback has been invaluable in enhancing the originality and logical coherence of our study. Based on your suggestions, we have revised and improved the results, and discussion and conclusion sections as follows:

 

Emphasizing Originality through Comparative Analysis
The study’s findings were compared with existing research (e.g., Giuliano & Narayan, 2003; Hanson, 1982) to recontextualize the influence of regional characteristics on passenger and freight flows. By revisiting these themes from a national balanced development perspective, this study extends beyond traditional data analysis to address gaps in prior research. Specifically, our integration of passenger and freight flow data with network centrality analysis provides a novel empirical approach that differentiates this research from existing studies and offers actionable policy insights.

 

Strengthening the Logical Flow between Results and Discussion
The revised discussion section aligns the findings with policy recommendations, ensuring a seamless transition. For example, the interaction between the Seoul Metropolitan Area and adjacent regions is shown to improve the efficiency of passenger and freight movements while enhancing functional connectivity between smaller cities and major hubs. This approach not only addresses the limitations of previous national balanced development policies but also underscores the potential policy contributions of this research to fostering regional connectivity.

 

Expanding and Enhancing the Conclusion Section
The conclusion has been revised to emphasize the contributions of this study and outline future research directions. By integrating passenger and freight data into a unified analysis, this study demonstrates the critical role of network centrality in strengthening inter-regional linkages. Furthermore, we have outlined actionable policy suggestions, including detailed, implementable strategies to strengthen functional connections between regions. The necessity of follow-up studies to validate the impact of these policies post-implementation is also discussed, underscoring the broader implications for sustainable regional development.

 

These revisions aim to address your comments comprehensively, thereby enhancing the study’s academic rigor and practical relevance. Thank you again for your valuable guidance.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors

Thank you very much submitting your paper to this land Journal. I found your paper interesting and after the improvement it will be interest to readers. I have the following suggestions to improve the quality of this manuscript.    

Abstract: Define what is block modelling and the scientific contribution of this study? You can define the block modelling at the background information and contribution of the study at the end.

Keywords: include block modelling. Use lower case. 

Introduction: Needs to support strong statements and facts/figures with citations/references. For example, Lines 28-30, 39-41, 42-45 needs to support with citations. Line 70, inform the readers about the structure of the paper.

Literature Review:  It has been reviewed the body on knowledge on travel characteristics and network analysis. However, it would be good to include one more section and discuss about the research gaps.

Materials and Methods: Section 3.1, include scope as sub-section.

Section 3.2; what is OD data? Please write it in full form. Include what hardware and software you have used.

Section 4 should be results and suggest to write it Results section. The research design is appropriate but can be improved. It is important to present your results clearly. Section 5 is also part of the results so this section/sub-section can be merged with section 4.  Both sections 4 and 5 are well presented.

Last section will be Section 5: Discussion and Conclusion. I am having difficulty to relate where your discussion part is? Please try to include discussion section (which is missing here). Relate your findings with theory and or previous studies/body of knowledge. The conclusion section is also very brief. The conclusions need to be supported by the results. Please expand it.

The English language is fine but some minor editing will be required.

 

Comments for author File: Comments.pdf

Comments on the Quality of English Language

The English language is fine. The minor editing will be required, and the errors can be rectified during the proofreading process. 

Author Response

Reviewer 2 Response Letter

1. 
   Abstract: Define what is block modelling and the scientific contribution of this study? You can define the block modelling at the background information and contribution of the study at the end.

Response: Thank you for your valuable feedback and constructive suggestions. Based on your comments, we have revised the Abstract to include a clear definition of block modeling and explicitly articulate the academic contributions of this study. The revisions are summarized as follows:

 

Definition of Block Modeling
As highlighted in your feedback, the absence of a definition for block modeling in the original Abstract may hinder readers’ understanding of the methodology employed in this study. To address this, we have included the following definition in the revised Abstract: "Block modeling is a method that clusters nodes performing similar roles within a network to identify functional regional structures." This addition clarifies the purpose and application of block modeling in our research and enhances the overall comprehensibility of the methodology.

 

Clarification of Academic Contributions
Following your recommendation, we have explicitly stated the academic contributions of this study in the concluding part of the Abstract. The revised Abstract highlights that this study presents an innovative approach to distinguishing passenger and freight flow patterns using block modeling. Additionally, by integrating this method with centrality and regression analyses, we provide a comprehensive analytical framework applicable to regional planning and policy formulation. These improvements ensure that the scholarly value of our research is clearly communicated to readers.

 

The revised Abstract incorporates your suggestions, presenting the study’s objectives, methodology, findings, and academic significance concisely and effectively. We hope that these revisions meet your expectations and further enhance the clarity and impact of this work. Thank you once again for your thoughtful and detailed feedback.

2. Keywords: include block modelling. Use lower case. 

Response: Based on your suggestion, we have added “block modeling” to the list of keywords and ensured that it is presented in lowercase. Thank you for your valuable feedback.

3. Introduction: Needs to support strong statements and facts/figures with citations/references. For example, Lines 28-30, 39-41, 42-45 needs to support with citations. Line 70, inform the readers about the structure of the paper.

Response: Thank you for highlighting the need to support strong assertions in the Introduction with evidence and citations, as well as the importance of clearly outlining the paper’s structure for the reader. Based on your valuable feedback, we have revised and enhanced the manuscript as follows:

 

Strengthening Assertions with Data and Citations:
To substantiate the severity of the concentration issue in the Seoul Metropolitan Area, we incorporated data and comparisons from World Bank (2009) and Lee et al. (2019). These references illustrate how the level of concentration in Korea surpasses global benchmarks, effectively contextualizing the issue as an extreme case.
In discussing the performance and limitations of the Korean government's balanced development policies, we cited Cho et al. (2017) to detail the achievements of innovation city projects and the establishment of Sejong City. These citations lend credibility to the discussion and highlight both successes and areas for improvement.

 

Clarifying the Structure of the Paper:
At the end of the Introduction, we added a concise overview of the paper’s structure. This addition ensures that readers can easily follow the progression of the research and understand how each section contributes to the overall narrative.

 

We believe these revisions address your concerns and significantly improve the clarity and scholarly rigor of the manuscript. Thank you again for your insightful feedback.

4. Literature Review:  It has been reviewed the body on knowledge on travel characteristics and network analysis. However, it would be good to include one more section and discuss about the research gaps.

Response: Thank you for your valuable feedback on improving the Literature Review section. In response to your insightful suggestions, we have made significant revisions and enhancements to the manuscript, which are summarized as follows:

 

Addition of a Section on Research Distinctiveness:
To highlight the unique contributions of this study, we added a new section titled "2.3 Research Distinctiveness." This section explicitly discusses how the study differs from existing research.

 

Addressing Limitations in Prior Research:
We identified that prior studies predominantly focused on either passenger or freight traffic in isolation. The new section emphasizes how this research bridges the gap by integrating an analysis of the interactions and differences between passenger and freight networks, which were largely overlooked in previous works.

 

Novel Insights into Urban Network Studies:
The added section underscores how the comparative analysis of passenger and freight network interactions and regional characteristics provides new perspectives in urban network research. This study goes beyond traditional frameworks by examining inter-regional dynamics and offering actionable insights for balanced development strategies.

 

We believe these revisions effectively address your concerns, enhancing the depth and clarity of the literature review and establishing the study's scholarly contributions more explicitly. Thank you again for your constructive feedback, which has been instrumental in refining the manuscript.

5. Materials and Methods: Section 3.1, include scope as sub-section.

Section 3.2; what is OD data? Please write it in full form. Include what hardware and software you have used.

Response: Thank you for your insightful feedback on the Materials and Methods section. Based on your suggestions, we have refined and enhanced Sections 3.1 and 3.2 to provide greater clarity and detail on the study's scope and data definition. Below are the specific revisions and improvements made:

 

Addition of Subsections in Section 3.1 and Clarification of Study Scope:
A dedicated subsection was added to detail the spatial scope of the study. The composition of each region and the number of cities, counties, and districts within each were explicitly stated. For example, the Seoul Metropolitan Area includes 77 units, while the Chungcheong region contains 36. By including these specifics, the study's scope and analytical units are communicated more clearly to the readers.

 

Enhanced Definition of OD Data and Software Usage:
The full term "Origin-Destination (OD)" was provided along with a precise definition of how passenger and freight travel routes were analyzed using these data. We elaborated on the specific roles of the software tools employed: Netminer 4 for block modeling and eigenvector centrality analysis, and SPSS 26 for multiple regression analysis. This enhancement improves the clarity and reproducibility of the analytical processes.

 

Expanded Explanation of Network Definitions:
Definitions for "Node" and "Link" were incorporated into the section. "Node" represents cities, counties, or districts within each region, while "Link" is defined as travel data derived from OD datasets. This explicit description ensures a better understanding of how the network is structured and analyzed.

 

We believe these revisions address your concerns and significantly enhance the comprehensibility and rigor of the Materials and Methods section. Thank you for your constructive recommendations, which have been pivotal in refining this part of the manuscript.

6. Section 4 should be results and suggest to write it Results section. The research design is appropriate but can be improved. It is important to present your results clearly. Section 5 is also part of the results so this section/sub-section can be merged with section 4.  Both sections 4 and 5 are well presented.

Response: Thank you for your meticulous feedback, which has been instrumental in enhancing the clarity and coherence of this manuscript. Based on your recommendations, Chapters 4 and 5 have been consolidated into a unified "Results" section, ensuring the findings and discussions are presented more effectively. Below is a summary of the improvements made:

 

Integration and Renaming of Chapters 4 and 5:
Chapters 4 and 5 have been merged into a single "Results" section to streamline the presentation. The sub-sections previously listed under Chapters 4.1 to 4.4 have been retained, covering key aspects such as passenger and freight traffic patterns and core area analysis. The structural organization enhances the logical flow and reader accessibility.

 

Enhanced Clarity in Describing Results:
The results have been presented systematically and concisely, emphasizing major traffic patterns and characteristics across regions. Tables and figures have been integrated to visually supplement key findings, such as traffic volume, centrality indices, and flow patterns, enabling readers to grasp the results intuitively and efficiently.

 

Unified Interpretation of Results and Discussion:
The section combines the analysis of traffic patterns and centrality with the explanatory factors for each region, such as population density, industrial structure, and land use. The findings from eigenvector centrality and multiple regression analyses are synthesized to highlight the distinct characteristics of passenger and freight traffic. Policy implications based on these differences are emphasized, showcasing actionable insights for balanced regional development.

 

We believe these revisions address your concerns and significantly improve the manuscript's coherence and analytical depth. Your valuable input has been crucial in elevating the quality of this work, and we extend our sincere gratitude for your thoughtful suggestions.

 

7. Last section will be Section 5: Discussion and Conclusion. I am having difficulty to relate where your discussion part is? Please try to include discussion section (which is missing here). Relate your findings with theory and or previous studies/body of knowledge. The conclusion section is also very brief. The conclusions need to be supported by the results. Please expand it.

Response: Thank you for your detailed and insightful feedback. Based on your suggestions, the manuscript has been revised and improved, particularly focusing on incorporating a distinct discussion section and emphasizing the connection between research findings, theoretical frameworks, and existing literature. Below is a summary of the key revisions and their corresponding explanations:

 

Inclusion of a Discussion Section

As you rightly pointed out, the previous submission lacked a clearly defined discussion section. In the revised version, a dedicated discussion section has been added, emphasizing the linkage between the study's findings and established theories or prior research (e.g., Giuliano & Narayan, 2003; Hanson, 1982). The new discussion includes:

 

• An analysis of the differences in passenger and freight travel centrality indices, connecting these distinctions to existing research. It reexamines the impact of regional characteristics and infrastructure on each type of travel.
• An exploration of regional imbalances from the perspective of national balanced development, suggesting policy directions to strengthen the connectivity between passenger and freight networks.

 

Strengthening the Connection Between Results and Discussion

The findings have been explicitly linked to the discussions to clarify their implications. For example:

 

• Passenger Travel: The influence of population density, service sector development, and cultural facilities is discussed in relation to existing theoretical frameworks, highlighting the drivers behind passenger centrality.
• Freight Travel: The impact of industrial areas, commercial zones, and factory infrastructure on freight network centrality is emphasized, elaborating on how these factors shape functional differences among regions.

 

Expanded Conclusion Section

The conclusion has been expanded to include more detailed policy implications and highlight the study's unique contributions. Key revisions include:

 

• A focus on actionable strategies for addressing metropolitan concentration through polycentric development and network enhancement.
• Policy recommendations to strengthen the roles of passenger and freight central regions, fostering complementary economic structures across regions.
• Emphasis on how this study differs from prior research and its contributions to advancing theoretical and practical approaches to urban network analysis.

 

These revisions aim to address your feedback comprehensively, ensuring the manuscript offers a more cohesive and rigorous analysis. Your constructive suggestions were invaluable in refining the quality and impact of this work, and we sincerely appreciate your efforts.

The English language is fine but some minor editing will be required.

 

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

This paper applied network analysis across South Korea to clarify regional characteristics in terms of both passenger and freight travel, and has achieved valuable results. However, the policy proposals described in “Discussion and Conclusion” are derived only from current situation analysis of regional characteristics, and are problematic because they involve leaps in logic. In order to increase the value of this paper and facilitate reader’s understanding, the following revisions should be made:

 

1) 3. Materials and Methods

The definitions of zone (spatial units of analysis) and network in this study are unclear. Specifically, it would be desirable to add explanations for the following:

- Are zones, the smallest unit of spatial analysis, si, gun, gu (cities and wards)?

- Are nodes the representative points of these zones?

- Are links defined as connecting all pairs of representative points of zones?

- Does the "areas" in 3.4.1, L263 represent zones or their representative points? The relationship with the definition of the five areas in Figure 1 is confusing.

- Please clarify the number of zones included in each of the five areas.

 

2) Table 2-3: Flow Map, Figure 5-6

Please add the boundaries of the five areas.

 

3) P11, L371

It should be stated in this part that “the metropolitan area” is “Block 1”.

 

4) P17, L595-601

 

This part includes policy proposals that a region-specific balanced national development strategies are need, and that it is effective for small- and medium-sized cities to strengthen their networks with larger central regions to achieve complementary growth. Although this study clarifies regional characteristics through analysis of the current situation, there is a leap in logic between the facts revealed by the analysis and those policy proposals. Detailed explanations of how the policy proposals were derived from the results of the analysis needs to be added.

 

Author Response

Reviewer 3 Response Letter

1) 3. Materials and Methods

The definitions of zone (spatial units of analysis) and network in this study are unclear. Specifically, it would be desirable to add explanations for the following:

- Are zones, the smallest unit of spatial analysis, si, gun, gu (cities and wards)?

- Are nodes the representative points of these zones?

- Are links defined as connecting all pairs of representative points of zones?

- Does the "areas" in 3.4.1, L263 represent zones or their representative points? The relationship with the definition of the five areas in Figure 1 is confusing.

- Please clarify the number of zones included in each of the five areas.

Response: Thank you for pointing out the lack of clarity in defining the spatial units and network concepts used in this study. Your valuable feedback has allowed us to refine and enhance the manuscript. Below is a summary of the revised content addressing the specific concerns:

 

Minimum Spatial Unit for Analysis

In this study, the minimum spatial unit of analysis is defined as si, gun, and gu (municipalities). Each si, gun, and gu serves as an individual node, representing the origin and destination in the OD dataset.

 

Node Definition

Nodes correspond to the representative points of each si, gun, and gu, and are based on administrative divisions and indicate the geographic locations serving as origins and destinations in the travel data.

 

Link Definition

Links represent the connections between pairs of nodes, defined based on the recorded travel volume in the OD dataset. Each link is weighted according to the magnitude of travel volume, encompassing all potential connections between node pairs.

 

Definition of “Areas” in Section 3.4.1

The term "areas" in Section 3.4.1 refers to the five regions (metropolitan and non-metropolitan areas) defined as the spatial scope of this study:

• Seoul Metropolitan Area (Block 1): 77 municipalities
• Chungcheong Region (Block 2): 36 municipalities
• Gangwon Region (Block 3): 18 municipalities
• Jeolla Region (Block 4): 42 municipalities
• Gyeongsang Region (Block 5): 75 municipalities

 

Relation to Figure 1

The five regions shown in Figure 1 delineate the study’s spatial scope. Within each region, si, gun, and gu are treated as individual nodes, forming the basis for analyzing interactions and network structures. The hierarchical structure comprises regions as higher-level entities and municipalities as lower-level units.

 

 

 

Additional Clarifications

This study employs nodes at the si, gun, and gu level to derive network structures and compares travel characteristics across the defined regions. The revised content has been incorporated into the methodology sections (3.1, 3.2, and 3.4) to explicitly articulate the spatial units and network definitions.

 

Your feedback has significantly enhanced the clarity and rigor of our methodological descriptions. Thank you once again for your detailed and insightful comments.

2) Table 2-3: Flow Map, Figure 5-6

Please add the boundaries of the five areas.

Response: Following the reviewer’s comments, the boundaries of the five regions have been added to Tables 2 and 3 (flowcharts) and Figures 5 and 6.

 3) P11, L371

It should be stated in this part that “the metropolitan area” is “Block 1”.

Response: As per the reviewer’s suggestion, we have explicitly clarified in P12, L449 that "Seoul Metropolitan Area" corresponds to "Block 1." In the revised text, the term "Seoul Metropolitan Area (Block 1)" is used to ensure that readers can clearly understand that this block refers to the Seoul Metropolitan Area without any ambiguity.

 

4) P17, L595-601

This part includes policy proposals that a region-specific balanced national development strategies are need, and that it is effective for small- and medium-sized cities to strengthen their networks with larger central regions to achieve complementary growth. Although this study clarifies regional characteristics through analysis of the current situation, there is a leap in logic between the facts revealed by the analysis and those policy proposals. Detailed explanations of how the policy proposals were derived from the results of the analysis needs to be added.

Response: Thank you for your detailed and insightful feedback regarding the logical connection between the policy recommendations and the analysis results. We recognize that while this study derives policy suggestions based on passenger and freight traffic data and network centrality analyses, the explanations previously provided lacked sufficient clarity to demonstrate the logical linkage between the results and recommendations. To address this, we have revised and supplemented the content as follows:

 

Enhancing the Logical Link Between Policy Recommendations and Analysis Results

The characteristics of passenger and freight traffic central areas identified in this study form the foundation of our policy proposals. The differences observed between these central areas are interpreted as follows:

Passenger Central Areas: High population density, advanced service industries, and concentrated cultural facilities indicate a strong correlation with passenger mobility. These areas should be further developed as hubs of urban activity to optimize passenger flows and enhance accessibility.

Freight Central Areas: The concentration of industrial zones, commercial spaces, and logistics infrastructure (e.g., factories, warehouses) highlights their critical role in freight mobility. Freight central areas should focus on improving logistics efficiency and supporting industrial activities.

Based on these findings, policies aimed at strengthening the linkages between passenger and freight central areas are proposed. These policies are designed to optimize economic resources and foster complementary growth across regions.

 

Adding Specific Implementation Directions for Policy Proposals

To clarify how the recommendations are grounded in the analysis results, the following actionable directions have been added:

 

Strengthening the Role of Passenger Hubs in the Seoul Metropolitan Area:
The Seoul Metropolitan Area (SMA) should leverage its high population density and complex transport network to serve as a hub for public transportation and international passenger flows. Enhancing these roles can improve efficiency and strengthen connectivity between the SMA and adjacent regions.

 

Expanding the Role of Freight Hubs in the Chungcheong and Gyeongsang Regions:
Identified as key freight hubs, the Chungcheong and Gyeongsang regions should reinforce their positions as logistics and manufacturing centers. Investments in logistics infrastructure and improvements to rail and road freight networks are essential for these regions.

 

Increasing the Network Participation of Small and Medium-Sized Cities:
Small and medium-sized cities should strengthen their connectivity with higher-level central areas to foster a model of complementary growth rather than isolated development. Policies should utilize the inter-regional traffic patterns identified in the analysis to maximize each region's strengths.

 

Linking Analysis Results to Policy Recommendations

The network centrality analysis results reveal that the Seoul Metropolitan Area, Chungcheong, and Gyeongsang regions form critical axes for both passenger and freight traffic. These patterns underscore the importance of enhancing inter-regional connectivity and resource allocation based on regional strengths as a cornerstone for national balanced development.

For instance, the Chungcheong region, identified as a pivotal intermediary between the SMA and the Gyeongsang region, demonstrates geographical advantages as a transit area. This aligns with the policy recommendation to develop the Chungcheong region as a logistics and freight hub, strengthening its role in the national network.

We believe these revisions effectively address the concerns raised and provide a clearer, more robust connection between the study’s findings and its policy implications. Thank you once again for your valuable input.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors

Thank you very much addressing the comments provided by me. The quality of English language needs to be improved so I would suggest to use professional proofreader when submitting your paper. I still have the following comments, so my suggestion is for minor revision.

Abstract:

I normally avoid to start sentence with verb. The first sentence can be written as

This study this study analyzes inter-regional traffic patterns and network structures using origin-destination (OD) data.

Section 2.3: This section needs to support with references and citations. For your example, you have mentioned previous studies, but, which previous studies (provide citations). The second sentence Research on passenger flows (provide citation) and studies on freight flows (provide citation). Methodologically, previous research (provide citations). This is just an example so this whole section needs to be revised.

Table 1: check the font type.

Reference 13, it is not consistent (All capital) with other references. Suggest to check all references and make sure that it is consistent according to suggested referencing style.

 

 

 

Comments on the Quality of English Language

It would be better to use a professional proofreader to improve the quality of this paper. Also,  all the references need to be checked.

Author Response

Reviewer 2 Response

Abstract:

1. I normally avoid to start sentence with verb. The first sentence can be written as

This study this study analyzes inter-regional traffic patterns and network structures using origin-destination (OD) data.

Response: We sincerely appreciate your valuable comment regarding the opening sentence of the abstract. Based on your suggestion, we have revised the first sentence as follows:

Original Sentence:
"To address regional imbalance in South Korea, this study analyzes inter-regional traffic patterns and network structures using origin-destination (OD) data."

Revised Sentence:
"This study analyzes inter-regional traffic patterns and network structures using origin-destination (OD) data."

This change reflects your recommendation to avoid starting a sentence with a verb, ensuring improved readability and alignment with academic writing conventions. Thank you for providing this constructive feedback, which has contributed to enhancing the quality of the manuscript.

 

2. Section 2.3: This section needs to support with references and citations. For your example, you have mentioned previous studies, but, which previous studies (provide citations). The second sentence Research on passenger flows (provide citation) and studies on freight flows (provide citation). Methodologically, previous research (provide citations). This is just an example so this whole section needs to be revised.

Response: We sincerely thank you for your insightful comments and detailed feedback regarding Section 2.3 of the manuscript. Your suggestions have been invaluable in enhancing the clarity and academic rigor of this section. In response, we have carefully revised the content as follows:

Incorporating Specific References: We have included precise references to support the statements about previous studies:

For passenger flows, we referenced Stead & Marshall (2001) and Headicar & Curtis (1994), which explore the influence of land use and transport network accessibility on travel patterns.

For freight flows, we added Giuliano & Narayan (2003) and Cervero (1996), which address logistics efficiency and industrial linkages. These references help substantiate our claims regarding the focus of earlier studies.

Addressing Methodological Gaps: We expanded on the methodological limitations of previous studies:

References such as Burger et al. (2014) and Saberi et al. (2017) were cited to highlight the reliance on centrality indices for evaluating regional importance, which often neglects structural similarities and interaction patterns within networks.

We clarified that while advanced methods like block modeling have been selectively applied in other domains, their application to passenger and freight flow data remains underexplored.

Emphasizing Policy Gaps: To address the absence of actionable policy implications in earlier research, we discussed how most studies, including Guo et al. (2023), primarily describe network characteristics without proposing concrete strategies to strengthen functional linkages between regions.

Revised Section Content: The revised Section 2.3 now provides a clear and well-supported analysis of prior research, emphasizing both the research gaps and the distinctiveness of our study. Specific citations and detailed explanations have been added to strengthen the section and meet your expectations.

We hope the revisions adequately address your comments and improve the overall quality and depth of Section 2.3. Thank you again for your valuable feedback, which has significantly contributed to refining our manuscript.

 

3. Table 1: check the font type.

Response: We sincerely thank you for your attention to detail and for pointing out the issue with the font type in Table 1. In response to your comment, we have carefully reviewed and corrected the font type in Table 1 to ensure consistency with the rest of the manuscript and adherence to the formatting guidelines of MDPI LAND.

 

4. Reference 13, it is not consistent (All capital) with other references. Suggest to check all references and make sure that it is consistent according to suggested referencing style.

Response: We sincerely thank the reviewer for pointing out the inconsistency in Reference 13. As per your suggestion, we have revised Reference 13 to align with the formatting style of the other references in the manuscript.

Furthermore, we carefully reviewed all the references in the manuscript to ensure consistency and adherence to the suggested referencing style. This adjustment has been implemented to enhance the clarity and uniformity of the reference list.

We appreciate your detailed observation, which has helped improve the overall quality of our manuscript.

 

Author Response File: Author Response.docx