On the Use of a Bike-Sharing System in Extreme Weather Events: The Case of Porto Alegre, Rio Grande do Sul, Brazil

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors, your paper deals with a very interesting topic. The aim is to analyze the use of a bike-sharing system during the flooding event caused by extreme rainfall in the municipality of Porto Alegre (in Brazil). Regarding the specific climate conditions of this municipality it can be a good example of relating the effects of possible climatic events on the choice of transport modes.

Although the overall impression about the paper is positive, it should be revised to add the proper anaylsis of the relationship between the data held, such as the trip profile, type of bicycle, origin and destination stations, geographic coordinates of the origin and destination stations, date, and trip duration. In the current version of the paper, the analysis is mainly based on the number of journeys for the months analysed. It is not sufficient, especially regarding the variety of data and possible conclusions that can be important in view of the stated objectives. Too little discussion of the data available also affects the limited discussion of the results (or rather the lack of it) in relation to other studies. So, I strongly recommend to supplement the paper with the missing information. I also recommend a broader discussion of the results to the environmental context. The paper address sustainable issues at very small extend so this aspect should be supplemented to fit the aim and scope of the journal. Urban mobility provides sustainable alternatives to urban commuting and this aspect should be discussed in the context of the available data on the bike sharing system in Porto Alegre and the objectives set, such as those set out in the article - (1) identification and quantification daily bicycle trips during periods of flooding and heavy rainfall, as well as the demographic characteristics of the affected areas and (2) analyzing of the relationship between rainfall indices and flooding using shared bicycles based on user profiles during extreme events and their repercussions. Only by discussing the issue in this way it will be possible to draw broader conclusions that can also be useful for other municipalities  exposed to different types of weather phenomena that want to introduce alternative forms of transport, such as bike sharing.

I hope, these remarks help you to work with your paper. Good luck!

Author Response

Comment 1)  Although the overall impression about the paper is positive, it should be revised to add the proper anaylsis of the relationship between the data held, such as the trip profile, type of bicycle, origin and destination stations, geographic coordinates of the origin and destination stations, date, and trip duration. In the current version of the paper, the analysis is mainly based on the number of journeys for the months analysed. It is not sufficient, especially regarding the variety of data and possible conclusions that can be important in view of the stated objectives. Too little discussion of the data available also affects the limited discussion of the results (or rather the lack of it) in relation to other studies. So, I strongly recommend to supplement the paper with the missing information.

Response 1: We would like to thank the reviewer for these valuable recommendations. In fact, we believe  that the inclusion of new analysis parameters may improve the results and support new discussions regarding the use of shared bicycles in extreme climate contexts. Hence, we followed the proposed recommendations and included additional variables, which were originally present in the considered dataset but that were not properly addressed in the submitted manuscript. Those variables are: trip profile, type of bicycle, trip duration and relationship with the trip profile, number of trips per day of the week, and by hour of the day. We selected the same month of 2023 to compare changes in usage patterns.

Regarding geographic coordinates, origin, and destination stations, this information was used to assist in marking location points in areas flooded by the storms. However, as suggested, we quantified the most frequently used stations. We depicted them on the flood map to better understand which areas of the city had a surge in shared bicycle use during the climate crisis period. Additionally, we included the trip flows between the most frequently used stations during 2023 and 2024, demonstrating the geographical shift in travel patterns and incorporating demographic components into the discussion.

The revised version of our manuscript includes all the mentioned improvements. Additionally, the new Table 3 presents a summarization of the analyzed variables. The newly performed analyses deepened the relevance of the data-driven analyses in our work.

 

Comment 2) I also recommend a broader discussion of the results to the environmental context. The paper address sustainable issues at very small extend so this aspect should be supplemented to fit the aim and scope of the journal. Urban mobility provides sustainable alternatives to urban commuting and this aspect should be discussed in the context of the available data on the bike sharing system in Porto Alegre and the objectives set, such as those set out in the article - (1) identification and quantification daily bicycle trips during periods of flooding and heavy rainfall, as well as the demographic characteristics of the affected areas and (2) analyzing of the relationship between rainfall indices and flooding using shared bicycles based on user profiles during extreme events and their repercussions.

Response 2: Regarding this comment, we have revised our manuscript to enhance its contributions and deepen the discussion within a broader sustainability-aware framework. We achieved this by expanding our discussion on key topics and extending our literature review, enabling more comprehensive comparisons with existing studies. Additionally, we incorporated more data on environmental issues and their connection to active transportation, along with demographic components, such as:

1. a) We used population density, which represents the number of inhabitants per square kilometer, as a population indicator that better expresses the relationship between population and geographic space than the total number of inhabitants per neighborhood. By including this indicator in the analysis, it was possible to conduct a more precise assessment of the impacts of flooding on more or less concentrated populations in the neighborhoods of Porto Alegre and the potential repercussions on urban mobility in that context.

b) Maps of the geolocation of health, education, and other types of establishments and households were included in the study to assess how the economic and social dynamics of the municipality of Porto Alegre were affected by the climatic event under analysis. Consequently, it also analyzed how public and private transportation systems had to be reorganized and the role of shared bicycle use during the most critical days of the climate emergency. Additionally, in order to better understand the travel flows, data about  origin and destination flows from two stations of the Bike POA Project were included in the analysis at two different time points to examine the possible influences of heavy rains and flooding on the travel dynamics considering these stations.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Dear authors, thank you for giving me the opportunity to review "On the Use of a Bike-Sharing System in Extreme Weather Events: The Case of Porto Alegre, Rio Grande do Sul, Brazil". I found this study interesting and relevant. However, I have the following suggestions:

1. The research gaps and motivations for this study could be more clearly stated.

2. The contributions should be better described. 

3. The results could be more clearly and comprehensively discussed.

4. Regarding the decreases in shared bike use at the beginning of May, the main contributing factor should be better discussed. In my opinion, with heavy rain, many people tend to use other public transport such as buses instead of shared bikes. I would suggest the authors consider this factor. In other words, at the beginning of May, the reduces of shared bike use is more likely to be contributed to the weather itself rather than flood.

5. The discussion part should be enhanced.

Author Response

Comment 1) The research gaps and motivations for this study could be more clearly stated.

Response 1: We would like to thank the reviewer for the time and effort in reviewing our manuscript. Considering this comment, additional discussions should be given to the gaps and motivations in the article, making them more precise. In this sense, the manuscript was revised with a more objective and accurate description of the gaps and motivations, as highlighted in the submitted revised version. In doing so, readers can better understand the relationship between shared bicycles and extreme weather events and the use of non-traditional data in obtaining results about active urban mobility.

 

Comment 2) The contributions should be better described.

Response 2:  As previously mentioned, the manuscript was carefully revised to more objectively discuss the contributions of non-traditional data to urban mobility and climate crisis issues, including shared bicycle systems, which in Brazil still prove to be an emerging service. We have made it clearer for the readers why our work is relevant in the considered scenario, and how new research could be positively impacted by it.

 

Comment 3: The results could be more clearly and comprehensively discussed.

Response 3: The results have been expanded and discussed more clearly and comprehensively, addressing the requested changes. Demographics, shared bicycle mobility, and climatic components have been included.

 

Comment 4: Regarding the decreases in shared bike use at the beginning of May, the main contributing factor should be better discussed. In my opinion, with heavy rain, many people tend to use other public transport such as buses instead of shared bikes. I would suggest the authors consider this factor. In other words, at the beginning of May, the reduces of shared bike use is more likely to be contributed to the weather itself rather than flood.

Response 4: The observation is relevant from the perspective of expanding the factors that may have impacted the reduction in shared bicycle use, which we totally agree with the reviewer about its relevance and timeliness. Particularly, we highlighted that the rainfall began in April, during which the use of shared bicycles was maintained, as shown in Figure 2. However, the intensification of rainfall at the end of April and the resulting flooding drastically impacted the perceived reductions. Furthermore, the public transportation system was severely affected by the suspension of bus and metro lines. These considerations are mentioned in the revised manuscript

 

Comment 5: The discussion part should be enhanced.

Response 5: As suggested, the discussions have been expanded, relating the obtained results to theoretical approaches to the topics addressed in the article.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This article analyzes the use of shared bicycles during floods caused by extreme rainfall in the city of Porto Alegre, Brazil. The resilience demonstrated by the shared bicycle system during this extreme climate event has enabled daily activities to be maintained, with a more significant impact on economic activities and a smaller impact on leisure activities. Although this article provides a comprehensive investigation of relevant work and data-driven analysis of scenario bicycle travel, there are still some areas that need improvement. Below are my specific opinions.

(1) In the third part, it is suggested to elaborate on the relationships between the variables in Table 1 and their role in discussing the viewpoint of this article.

(2) In section 3.1, Figure 1 can indicate the key areas affected by floods and provide relevant information or the percentage of affected population next to the figure, making the content of the article more visually presented in the form of a graph.

(3) This article explores the use of extreme weather shared bicycle systems, but there is relatively little connection between the data survey and the shared bicycle system. It is recommended to clarify the survey content and related data in the third part when describing the connection with the shared bicycle system.

(4) The analysis of the results in Part 4 is relatively simple. Figure 4 describes the Pearson correlation coefficient between rainfall and travel frequency. It is suggested to explain why Pearson correlation coefficient is used for analysis and how to analyze it, so as to make the content of the article more substantial and the analysis evidence more complete.

(5) Suggestions for promoting the shared bicycle system in the city can be supplemented by planning from market research, service scope, future development measures, and other aspects.

(6) It is recommended that the author consider more relevant details when drawing to make the image more detailed and rich. In terms of references, it is suggested to cite some prefaces from recent years.

Author Response

Comment 1) In the third part, it is suggested to elaborate on the relationships between the variables in Table 1 and their role in discussing the viewpoint of this article.

Response 1: In first place, we would like to thank the reviewer for the time and effort in reviewing our manuscript.

It is essential to highlight that including new analysis parameters can make the results more comprehensive and support new discussions regarding using shared bicycles in extreme climate contexts. Thus, we followed the proposed recommendations and included additional variables present in the dataset that were not addressed in the previous version but contributed to the results, such as trip profile, type of bicycle, trip duration and its relationship with the trip profile, number of trips per day of the week, and by hour of the day. We selected the same period of 2023 to compare changes in usage patterns.

Regarding geographic coordinates, as well as origin and destination stations, these were used to assist in marking location points in areas flooded by the storms. However, as suggested, we quantified the most frequently used stations. We displayed them on the flood map to better understand which areas of the city used shared bicycles during the climate crisis period. Additionally, we included the travel flows between the most frequently used stations during 2023 and 2024, demonstrating the geographical shift in travel patterns and incorporating demographic components into the discussion.

 

Comment 2) In section 3.1, Figure 1 can indicate the key areas affected by floods and provide relevant information or the percentage of affected population next to the figure, making the content of the article more visually presented in the form of a graph.

Response 2: Thank you for considering item 3.1 and the figure related to the area of Porto Alegre. Indeed, the map could be improved for better visual clarity. Therefore, we have included the affected areas to enhance its presentation. The information on the percentage of the impacted population is provided in the paragraph preceding the map, indicating that approximately 12% of people were affected.

 

Comment 3) This article explores the use of extreme weather shared bicycle systems, but there is relatively little connection between the data survey and the shared bicycle system. It is recommended to clarify the survey content and related data in the third part when describing the connection with the shared bicycle system.

Response 3: Thank you for your insightful feedback. In response to your suggestion, we have revised the third part of the article to establish a clearer connection between the data survey and the shared bicycle system. Specifically, we have included new discussions that better link the study’s focus—shared bicycle trips in extreme weather conditions—with demographic density and service availability as background variables. These additions aim to enhance the contextual understanding of how these factors influence bicycle-sharing patterns during climate emergencies, thereby strengthening the coherence between the data and the study’s main objective.

 

Comment 4) The analysis of the results in Part 4 is relatively simple. Figure 4 describes the Pearson correlation coefficient between rainfall and travel frequency. It is suggested to explain why Pearson correlation coefficient is used for analysis and how to analyze it, so as to make the content of the article more substantial and the analysis evidence more complete.

Response 4: We appreciate the question and suggestion. However, after reviewing the article and retesting the data—also extending the analyses to May 2023—we decided to remove the Pearson Correlation, as it did not contribute to the results we initially expected. Therefore, we conducted a more in-depth descriptive analysis of the data.

 

Comment 5) Suggestions for promoting the shared bicycle system in the city can be supplemented by planning from market research, service scope, future development measures, and other aspects.

Response 5: To enhance the promotion of the shared bicycle system in the city, many factors are relevant and have been discussed in our revised manuscript. In a first glance, analyses like the one performed in our manuscript are valuable to push governments to invest more resources in promoting this type of modal. Additionally, by analyzing key factors such as demographics, commuting patterns, and user feedback, service accessibility and availability could be further enhanced. Looking ahead, future development measures might focus on technological advancements, infrastructure improvements, and policy support. We have discussed all these issues in the revised manuscript.

 

Comment 6) It is recommended that the author consider more relevant details when drawing to make the image more detailed and rich. In terms of references, it is suggested to cite some prefaces from recent years.

Response 6: We followed the proposed guidelines to conduct a bibliographic survey of recent studies. Therefore, references from the year 2025 were included. We also added more thematic maps that can be more didactic for understanding, with enhanced observation quality.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have answered my questions. I would recommend accept.