Analyzing the Impact of Road Accidents on Carbon Dioxide Emissions in Freeway Traffic: A Simulation and Statistical Modeling Approach
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsDear Authors!
Thank you for submitting your manuscript “Analyzing the effects of road accidents on carbon dioxide emissions in freeway traffic” to the Journal of “Sustainability”. Your work on finding a nonparametric model that can describe air pollution patterns with sufficient reliability when non-standard traffic situations arise is certainly useful for the scientific community and economic applications. The results of the work in the future can be developed and used in the development of strategies for reducing emissions of both greenhouse and acid-forming gases. In addition, the manuscript is well structured and has accessible illustrative material, which is also a positive feature of your article. Despite this, I must recommend that you improve some aspects of your article.
1) I would like to see in the work a more in-depth analysis of modern works devoted to topics similar to yours. In particular, I would like to know if there are articles that consider models that evaluate the behavior of other gaseous impurities (for example, nitrogen oxides, ozone).
2) Although the illustration material in your work is commendable, you need to improve it. For example, in Figure 6. It is necessary to clarify what “count” is? And also it is necessary to clarify what is reflected on the color scale on the right?
3) Figure 7 and 8 use lower case when writing CO2.
Comments on the Quality of English Language
Minor editing.
Author Response
Reviewer #1
Thank you for submitting your manuscript “Analyzing the effects of road accidents on carbon dioxide emissions in freeway traffic” to the Journal of “Sustainability”. Your work on finding a nonparametric model that can describe air pollution patterns with sufficient reliability when non-standard traffic situations arise is certainly useful for the scientific community and economic applications. The results of the work in the future can be developed and used in the development of strategies for reducing emissions of both greenhouse and acid-forming gases. In addition, the manuscript is well structured and has accessible illustrative material, which is also a positive feature of your article. Despite this, I must recommend that you improve some aspects of your article.
Response: Thank you for the overall comments.
Comment 1: I would like to see in the work a more in-depth analysis of modern works devoted to topics similar to yours. In particular, I would like to know if there are articles that consider models that evaluate the behavior of other gaseous impurities (for example, nitrogen oxides, ozone).
Response: While we acknowledge the necessity for a more thorough examination of contemporary works, it's crucial to highlight the scarcity of studies directly linking highway accident response efficiency to traffic flow characteristics such as volume and vehicle type. Existing studies predominantly focus on carbon dioxide or carbon emissions, with limited exploration of other relevant gases pertinent to our study. In the Introduction section, we have incorporated recent advancements in related research, noting that the literature highlighted primarily centers on carbon emissions.
Comment 2: Although the illustration material in your work is commendable, you need to improve it. For example, in Figure 6. It is necessary to clarify what “count” is? And also it is necessary to clarify what is reflected on the color scale on the right?
Response: In Figure 6, the "count" represents the amount of data per second. We compare and analyze the traffic characteristics in different scenarios by observing the distribution of data volume in different velocity-acceleration grids in each scenario, which facilitates the modeling afterwards "count" represents the amount of data per second. We compare and analyze the traffic characteristics in different scenarios by observing the distribution of data volume in different velocity-acceleration grids in each scenario, which facilitates the modeling afterwards. We have improved the illustrations as required.
Comment 3: Figure 7 and 8 use lower case when writing CO2.
Response: We have improved the illustrations as required.
Reviewer 2 Report
Comments and Suggestions for AuthorsThe paper is well written, innovative, and well structured. I think it can be published. Some details need to be modified.
1) Do you need to unify the units of speed? Km/h or mph?
2) Have a similar method and study performed before by other researchers?
3)What are your new contributions?
Author Response
The paper is well written, innovative, and well structured. I think it can be published. Some details need to be modified.
Response: Thank you for the overall comments.
Comment 1: Do you need to unify the units of speed? Km/h or mph?
Response: We have standardized the speed units in the article to “km/h”.
Comment 2: Have a similar method and study performed before by other researchers?
Response: While we acknowledge the necessity for a more thorough examination of contemporary works, it's crucial to highlight the scarcity of studies directly linking highway accident response efficiency to traffic flow characteristics such as volume and vehicle type. Existing studies predominantly focus on carbon dioxide or carbon emissions, with limited exploration of other relevant gases pertinent to our study. In the Introduction section, we have incorporated recent advancements in related research, noting that the literature highlighted primarily centers on carbon emissions.
Comment 3: What are your new contributions?
Response: Our study contributes to the existing body of research by directly establishing a statistical relationship between the additional CO2 emissions resulting from highway accidents and the methods of accident management. Our study enriches the current methodologies for predicting accident-related emissions and addresses issues such as poor applicability observed in similar studies on emission prediction. Furthermore, Our study synthesizes statistical patterns to offer guidance for further exploration and analysis in this field.
Reviewer 3 Report
Comments and Suggestions for Authors
The paper attempted to explore the effects of road accidents on carbon dioxide emissions on freeway. After reviewing the paper, it was found that the scientific contributions of the paper are limited. In addition, the presentation needs to improved. Here are several comments.
1. The title does not accurately reflect the study’s objectives and findings.
2. The introduction is inadequately written, lacking a seamless connection and progression in presenting the background, research gap, and scope of the study. This impedes a clear understanding of the study’s contribution to the existing literature.
3. What is the purpose of section 2?
4. The study did not discuss the rationale behind the selection of cars and trucks only.
5. There is a notable absence of relevant discussion regarding the exclusion of variables such as car model and age, both of which are pivotal in understanding CO2 emissions.
6. The speed-acceleration functions (desired acceleration functions) for cars and trucks in this study are calibrated based on the research findings of another study, itself relying on data from 2011. Given the significant changes since then, the reliability the present results are questionable.
7. The presented findings and analyses lack adequate interpretation and discussion, leaving the significance of the findings unclear.
Comments on the Quality of English Language
Moderate editing of English language required.
Author Response
Reviewer #3:
The paper attempted to explore the effects of road accidents on carbon dioxide emissions on freeway. After reviewing the paper, it was found that the scientific contributions of the paper are limited. In addition, the presentation needs to improved. Here are several comments.
Response: Thank you for the overall comments.
Comment 1: The title does not accurately reflect the study’s objectives and findings.
Response: We have revised the title of the paper to “Analyzing the Impact of Road Accidents on Carbon Dioxide Emissions in Freeway Traffic: A Simulation and Statistical Modeling Approach”.
Comment 2: The introduction is inadequately written, lacking a seamless connection and progression in presenting the background, research gap, and scope of the study. This impedes a clear understanding of the study’s contribution to the existing literature.
Response: While we acknowledge the necessity for a more thorough examination of contemporary works, it's crucial to highlight the scarcity of studies directly linking highway accident response efficiency to traffic flow characteristics such as volume and vehicle type. Existing studies predominantly focus on carbon dioxide or carbon emissions, with limited exploration of other relevant gases pertinent to our study. In the Introduction section, we have incorporated recent advancements in related research, noting that the literature highlighted primarily centers on carbon emissions.
Comment 3: What is the purpose of section 2?
Response: The section 2 focuses on a brief introduction to the content of the later chapters and describes the design of the logical framework of this study to help the reader quickly understand the outline of the article.
Comment 4: The study did not discuss the rationale behind the selection of cars and trucks only.
Response: We agree that in the context of various vehicle types, their unique speed-acceleration profiles and engine specifications invariably influence the emission attributes within traffic flow dynamics. Nonetheless, capturing the intricate composition of vehicles poses a challenge when employing discrete or continuous variables. Introducing categorical variables to model these complexities tends to convolute the analysis, diverging from the primary objective of developing a streamlined and user-friendly model. Consequently, we simplified the vehicle composition into two distinct categories: cars and trucks. We added that basis to the article.
Comment 5: There is a notable absence of relevant discussion regarding the exclusion of variables such as car model and age, both of which are pivotal in understanding CO2 emissions.
Response: The impact of vehicle interior features and age on emissions has not been included in this study. This decision is rooted in the study's focus on meso-level usage scenarios, particularly highway segments, where acquiring reliable the data of vehicle interior features and age proves challenging. Furthermore, consideration of this factor is not conducive to the application of the model.
Comment 6: The speed-acceleration functions (desired acceleration functions) for cars and trucks in this study are calibrated based on the research findings of another study, itself relying on data from 2011. Given the significant changes since then, the reliability the present results are questionable.
Response: The velocity-acceleration distribution curves referenced in the simulation are indeed from the 2011 vehicle operating data. However, the driving speed-acceleration characteristics of vehicles have not changed significantly since 2011, and we use the relevant literature from 2022 as proof. Taking a small car as an example, as shown in the figure below, the difference between the scatter distribution and the trend of the quantile line is not obvious in the two studies, and the characteristic indexes such as the maximum speed, the maximum acceleration and the speed at the time of the maximum acceleration are not very much different from each other. Therefore, we believe that it is meaningful to use the 2011 vehicle operation data for simulation modeling in this study.
Figure 1. Speed-Acceleration distribution of the car by Atlanta Regional Commission (2011) (a) and Long Y. (2022) (b).
Reference:
- Long Y., Lv N., Xu J. (2022). Longitudinal acceleration characteristics of vehicles at signalized intersections. China Science Paper, 17(6), 615-622.
Comment 7: The presented findings and analyses lack adequate interpretation and discussion, leaving the significance of the findings unclear.
Response: We have added further explanation and discussion of the findings in the text.
Reviewer 4 Report
Comments and Suggestions for AuthorsTo study the additional CO2 emission during accidents occurrence is a very interesting subject. But some important problems are not clearly elaborated in the manuscript as follows,
1.How to define addtional emission? Or what is the necessary emission? What condition does the additonal emission occur?
2.If the emission factors calculated from MOVES are not based on field data, it has less meaning for study.
3. Are you sure that the CO2 emission would increase during the accident ? For example, all the vehicles would stop its engine when the accidents occurs for an enough long period, where does the CO2 emission come from?
Author Response
Reviewer #4:
To study the additional CO2 emission during accidents occurrence is a very interesting subject. But some important problems are not clearly elaborated in the manuscript as follows.
Response: Thank you for the overall comments.
Comment 1: How to define addtional emission? Or what is the necessary emission? What condition does the additonal emission occur?
Response: The additional CO2 emission is the difference between the total CO2 emissions of the scenario with an accident and the total CO2 emissions of the scenario without an accident (with an accident duration of 0 min) under identical conditions. We have added further explanation and discussion of the findings in the text.
Comment 2: If the emission factors calculated from MOVES are not based on field data, it has less meaning for study.
Response: We agree that real data should be used as much as possible when calculating emission factors using MOVES. But as added in the article, real trajectory data is often difficult to represent the whole sample overall. However, the current microsimulation software (VISSIM, AnyLogic, etc) can effectively capture the driving behaviors of vehicles following a traffic accident within microscopic traffic flow scenarios. Moreover, compared to real-world data, the microsimulation software demonstrates its capability to efficiently and accurately acquire traffic flow data across a spectrum of accident scenarios. For problems in practical applications, we use simulation data mainly to provide a valuable law, which can be used in future applications to correct the parameters of the model based on the actual data in order to avoid the problem of distortion of the simulation data.
Comment 3: Are you sure that the CO2 emission would increase during the accident ? For example, all the vehicles would stop its engine when the accidents occurs for an enough long period, where does the CO2 emission come from?
Response: We apologize that this post has caused you such confusion. In the case of traffic accidents, our research looks at the period from the time of the accident until the congestion has all but dissipated after the accident is over. In your example, a large number of vehicles are stopped in a queue with their engines turned off for a period of time after the accident, but once the accident area is cleared, the queue begins to dissipate. However, once the accident area is cleared and the queue of vehicles begins to dissipate, the vehicle fleet enters a state of frequent acceleration and deceleration with stops and starts, and the fuel consumption and emissions in this state are very high. Therefore, if this part of the state is also taken into account, the emissions caused by the whole accident will be significantly larger than the emissions of the fleet when there is no accident.
Reviewer 5 Report
Comments and Suggestions for AuthorsYour efforts in developing a nonparametric model to describe air pollution patterns under non-standard traffic situations are valuable for both the scientific community and economic applications. The outcomes of your research have the potential to contribute to the formulation of strategies aimed at reducing emissions of greenhouse and acid-forming gases. Additionally, the manuscript is well-organized with clear illustrative material, enhancing its overall quality. However, I recommend addressing some areas for improvement.
It would be beneficial to incorporate a more thorough analysis of contemporary works related to your topic. Specifically, exploring whether there are articles examining models assessing the behavior of other gaseous impurities, such as nitrogen oxides and ozone, would enhance the depth of your work.
While the visual aids in your manuscript are commendable, improvements are needed. For instance, in Figure 6, it is essential to provide clarification on what "count" represents. Additionally, a clear explanation of the elements reflected in the color scale on the right is necessary.
Figures 7 and 8 use lowercase when writing "CO2." Please ensure consistent capitalization for clarity and adherence to standard conventions.
Is there a need to standardize the units of speed, either in kilometers per hour (km/h) or miles per hour (mph)?
Has a comparable methodology and study been conducted previously by other researchers?
What novel contributions do your findings bring to the existing body of knowledge?
Author Response
Reviewer #5:
Your efforts in developing a nonparametric model to describe air pollution patterns under non-standard traffic situations are valuable for both the scientific community and economic applications. The outcomes of your research have the potential to contribute to the formulation of strategies aimed at reducing emissions of greenhouse and acid-forming gases. Additionally, the manuscript is well-organized with clear illustrative material, enhancing its overall quality. However, I recommend addressing some areas for improvement.
Response: Thank you for the overall comments.
Comment 1: It would be beneficial to incorporate a more thorough analysis of contemporary works related to your topic. Specifically, exploring whether there are articles examining models assessing the behavior of other gaseous impurities, such as nitrogen oxides and ozone, would enhance the depth of your work.
Response: While we acknowledge the necessity for a more thorough examination of contemporary works, it's crucial to highlight the scarcity of studies directly linking highway accident response efficiency to traffic flow characteristics such as volume and vehicle type. Existing studies predominantly focus on carbon dioxide or carbon emissions, with limited exploration of other relevant gases (such as nitrogen oxides and ozone) pertinent to our study.
Comment 2: While the visual aids in your manuscript are commendable, improvements are needed. For instance, in Figure 6, it is essential to provide clarification on what "count" represents. Additionally, a clear explanation of the elements reflected in the color scale on the right is necessary.
Response: In Figure 6, the "count" represents the amount of data per second. We compare and analyze the traffic characteristics in different scenarios by observing the distribution of data volume in different velocity-acceleration grids in each scenario, which facilitates the modeling afterwards "count" represents the amount of data per second. We compare and analyze the traffic characteristics in different scenarios by observing the distribution of data volume in different velocity-acceleration grids in each scenario, which facilitates the modeling afterwards. We have improved the illustrations as required. In Figure 6, the "count" represents the amount of data per second. We compare and analyze the traffic characteristics in different scenarios by observing the distribution of data volume in different velocity-acceleration grids in each scenario, which facilitates the modeling afterwards "count" represents the amount of data per second. We compare and analyze the traffic characteristics in different scenarios by observing the distribution of data volume in different velocity-acceleration grids in each scenario, which facilitates the modeling afterwards. We have improved the illustrations as required.
Comment 3: Figures 7 and 8 use lowercase when writing "CO2." Please ensure consistent capitalization for clarity and adherence to standard conventions.
Response: We have improved the illustrations as required.
Comment 4: Is there a need to standardize the units of speed, either in kilometers per hour (km/h) or miles per hour (mph)?
Response: We have standardized the speed units in the article to “km/h”.
Comment 5: Has a comparable methodology and study been conducted previously by other researchers?
Response: We agree that there have been studies that have explored similar issues, but there are not many relevant studies. For example, the study by Son, Y.T. et al. provides a quantitative discussion of the relationship between carbon emissions caused by highway events and event management measures. However, unlike this study, it did not propose a mathematical model with wider applicability, but only an index table for query use. We have supplemented this section in the introductory chapter.
Comment 6: What novel contributions do your findings bring to the existing body of knowledge?
Response: Our study contributes to the existing body of research by directly establishing a statistical relationship between the additional CO2 emissions resulting from highway accidents and the methods of accident management. Our study enriches the current methodologies for predicting accident-related emissions and addresses issues such as poor applicability observed in similar studies on emission prediction. Furthermore, Our study synthesizes statistical patterns to offer guidance for further exploration and analysis in this field.
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThank you for your time! I believe that this manuscript can be accepted for publication.
Reviewer 3 Report
Comments and Suggestions for AuthorsAll my comments have been addressed. I have no further comments.
Reviewer 4 Report
Comments and Suggestions for AuthorsNo more comments.
