Review Reports - Development of Representative Urban Driving Cycles for Congested Traffic Conditions in Guayaquil Using Real-Time OBD-II Data and Weighted Statistical Methods

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

In this paper, the authors take Guayaquil as an example, use real-time OBD data and weighted statistical methods to find the development of representative urban driving cycles for congested traffic conditions.The results enrich the existing theoretical research models and have certain theoretical meaning. Therefore, I think the paper can be accepted. In addition, the following are the few comments, which may be included while revision.

The methods used in this paper are simplistic, the research topic lacks significant value, and there is a lack of substantial innovation.
The title should include "Guayaquil", as the data, methodology, conclusions, and other elements of this paper are closely associated with Guayaquil and do not possess general applicability.
Abstract." The results revealed significant differences in average speed, idle time, and acceleration patterns across the various routes, reflecting the heterogeneous traffic dynamics in each urban zone". In fact, this conclusion is self-evident without the need for research.
Section 3.3.Table 3 presents the weights of each variable, but this method of directly determining weights is overly simplistic and subjective. The authors need to adopt a more objective method to calculate the weights.
Section 4.6.It is suggested that the authors merge Sections 4.6.1–4.6.4 into one section. The content of these subsections is redundant, and the analysis is superficial, so they do not need to occupy a large amount of space.
Section 4.7.The authors' analysis of Tables 12–14 merely lists the numbers in the tables, rather than summarizing and analyzing the patterns and underlying reasons behind these numbers, resulting in a lack of depth.
The list of references should be extended to include some recent papers as follow.

1) Optimal charge scheduling and on-board control of an urban electrified BRT fleet considering synthetic representative driving cycles[J].Scientific Reports, 2024, 14(1).DOI:10.1038/s41598-024-55725-y.

2) A multi-value cellular automata model for multi-lane traffic flow under lagrange coordinate.Computational and Mathematical Organization Theory. https://doi.org/10.1007/s10588-021-09345-w

Author Response

Comment:

The methods used in this paper are simplistic, the research topic lacks significant value, and there is a lack of substantial innovation.

Response:

We sincerely thank the reviewer for this observation. We acknowledge the importance of clarifying both the methodological rigor and the innovative contributions of our study. Accordingly, we have revised the manuscript to highlight the originality and practical significance of our work:

Abstract (pp. 1) by adding: “These cycles provide practical tools for vehicle certification and sustainable mobility policies in congested cities.” This explicitly highlights the applied impact of our contribution.

Introduction (pp. 3): We now emphasize that this is the first study to develop representative driving cycles specifically for Guayaquil, the most populated and congested city in Ecuador. Unlike previous works conducted in Quito, Cuenca, or Esmeraldas, our approach integrates high-resolution OBD data (0.1 s intervals) and multiple route repetitions, ensuring a more accurate representation of real urban traffic conditions.

Methodology (pp. 7–8): We strengthened this section to highlight the robustness of our methods. The revised text clarifies that we processed over 45 repetitions across four strategic urban routes, used high-frequency OBD data subsequently filtered to 1-second resolution, and applied both normality tests and weighted statistical selection. This combined approach provides greater precision and replicability compared to earlier Ecuadorian studies relying mostly on lower-frequency GPS data.

Discussion (pp. 19–20): We now explicitly underline the innovative aspect of integrating high-resolution OBD data with weighted statistical criteria in a highly congested Latin American context. Furthermore, we stress the novelty of systematically comparing Guayaquil’s cycles with both international reference cycles (FTP-75, NEDC, HWFET) and other Ecuadorian cities. This comparative framework reveals unique driving patterns (e.g., idle time, acceleration ratios, stop frequency) that had not been previously reported.

Conclusions (pp. 20–21): We expanded this section to reinforce the practical relevance of the study. The new text states that the proposed cycles can directly support vehicle certification and emission regulation processes led by INEN and ANT, as well as inform sustainable mobility policies in Guayaquil. Moreover, the cycles can be used as input for future emission simulations, the evaluation of alternative vehicle technologies (electric and hybrid), and for urban transport planning in cities facing similar congestion challenges.

Comment:

The title should include "Guayaquil", as the data, methodology, conclusions, and other elements of this paper are closely associated with Guayaquil and do not possess general applicability.

Response:

We agree with the reviewer’s suggestion. Accordingly, we have revised the title to:
“Development of Representative Urban Driving Cycles for Congested Traffic Conditions in Guayaquil Using Real-Time OBD Data and Weighted Statistical Methods” (p. 1).

Comment:

" The results revealed significant differences in average speed, idle time, and acceleration patterns across the various routes, reflecting the heterogeneous traffic dynamics in each urban zone". In fact, this conclusion is self-evident without the need for research.

Response:

We thank the reviewer for the observation. We agree that traffic heterogeneity across urban routes may be expected in general terms; however, the purpose of our study was not simply to state this fact, but to quantify these differences through high-resolution OBD data and translate them into representative driving cycles that can be used for emissions modeling, vehicle certification, and sustainable mobility planning. To clarify this applied value, we have revised the abstract on page 1 to read:

“The results provided quantified evidence of variations in average speed, idle time, and acceleration patterns across the routes, which were transformed into representative driving cycles. These cycles provide a more accurate basis for emission modeling, vehicle certification, and transport policy design in congested cities such as Guayaquil.”

Comment:

Section 3.3.Table 3 presents the weights of each variable, but this method of directly determining weights is overly simplistic and subjective. The authors need to adopt a more objective method to calculate the weights.

Response:

We appreciate this valuable comment. We clarify that the weighting method applied in Table 3 is not arbitrary but follows approaches previously validated in the literature for the construction of representative driving cycles in Ecuador (e.g., Cuenca, Esmeraldas, Ambato-Riobamba) and other international contexts (India, Hong Kong, Mexico). The assigned weights reflect the relative influence of each parameter (speed, idle time, number of stops, acceleration time) on the representativeness of the driving cycle, as documented in earlier studies.

We have added a paragraph in Section 3.3 (p. 8-9) clarifying that the weights were based on both literature evidence and the practical significance of each variable in fuel consumption and emission estimation. We agree that more advanced objective methods (e.g., Analytic Hierarchy Process, entropy weighting) could further refine the weighting process, and we will highlight this as a recommended line for future research.

Comment:

Section 4.6.It is suggested that the authors merge Sections 4.6.1–4.6.4 into one section. The content of these subsections is redundant, and the analysis is superficial, so they do not need to occupy a large amount of space.

Response:

The subsections were eliminated.

Comment:

Section 4.7.The authors' analysis of Tables 12–14 merely lists the numbers in the tables, rather than summarizing and analyzing the patterns and underlying reasons behind these numbers, resulting in a lack of depth.

Response:

We appreciate the reviewer’s observation. We agree that the original version of Section 4.7 focused mainly on reporting the values shown in Tables 12–14, without sufficiently highlighting the underlying patterns and causes. In the revised version (p.18), we have expanded the analysis to include a deeper interpretation of the results. Specifically, we now explain how factors such as traffic density, road type (urban vs. highway), and infrastructure characteristics contribute to differences in average speed, idle time, number of stops, and acceleration patterns across Guayaquil’s routes and in comparison, with other national and international cycles. This enriched discussion adds more context and depth, allowing the reader to better understand not only the numerical differences but also their implications for emissions modeling, traffic efficiency, and urban planning.

Comment:

The list of references should be extended to include some recent papers as follow.

2) A multi-value cellular automata model for multi-lane traffic flow under lagrange coordinate. Computational and Mathematical Organization Theory. https://doi.org/10.1007/s10588-021-09345-w

Response:

The references were included in Introduction section (p. 2)

Reviewer 2 Report

Comments and Suggestions for Authors

This study holds significant value, offering valuable insights for the design and testing of vehicles tailored to specific regions. The authors' research is thorough, and no major revisions are necessary. My sole concern pertains to how automotive engineers and researchers can access and utilize the authors' data. The authors should include a data availability statement to address this.

Author Response

Comment:

Response:

We thank the reviewer for this valuable suggestion. In accordance with the journal’s policy, we have included (p.22) a Data Availability Statement in the revised manuscript. The statement reads:

“The data supporting the findings of this study are available from the corresponding authors upon reasonable request. Due to confidentiality agreements with the research participants, the raw driving data cannot be made publicly available. However, processed datasets and analysis outputs used in this study are available upon request from the corresponding authors.”

Reviewer 3 Report

Comments and Suggestions for Authors

Page 1, Lines 23–25. Firstly, only selected compounds are listed. Secondly, I do not understand why internal combustion engines should emit lead compounds, since unleaded fuels have been used for many years in the civilized world.

Page 1, Lines 23–25. Why do the authors not use subscripts (CO₂ instead of CO2)? This applies to the entire text.

Page 5, Lines 168–170. I am trying to understand the choice of the vehicle, but in Table 1 it is indicated that the model is ten years old. Does this mean that in this country used cars are most commonly purchased? Why was a younger car not selected? What is the vehicle’s mileage?

Page 5, Lines 172–174. So far, the authors have referred to the OBD standard, which is even listed in the keywords. Suddenly, the OBD II standard appears without any comment. The authors must be aware that these are not the same?

Page 8, Table 2. What is the purpose of presenting uncontrolled variables? They are not referenced in any other part of the text. Why was the octane number included among these variables? Was it not known which fuel was used to refuel the car, e.g., 95 or 98 octane?

Pages 12–14, Tables 8–11. Why was the notation changed, i.e., using a comma instead of a dot for decimal numbers? In Table 12, everything returns to the standard format. Please unify the notation.

Page 19. The list of abbreviations is incomplete. There are many more terms in the text that should be included here.

Author Response

Comment:

Response:

We thank the reviewer for this observation. We agree that the original text was not sufficiently precise. In the revised version we have corrected this by (i) generalizing the description of typical pollutants emitted by internal combustion engines and (ii) removing the reference to lead compounds, since unleaded fuels are now standard worldwide. The revised sentence (p. 1, lines 23–25) now reads:

“Internal combustion engines release substances such as carbon monoxide (CO), carbon dioxide (CO₂), nitrogen oxides (NOx), and unburned hydrocarbons (HC), which are harmful to air quality and public health.”

This correction avoids the misleading mention of lead compounds and provides a more accurate description of emissions.

Comment:

Page 1, Lines 23–25. Why do the authors not use subscripts (CO₂ instead of CO2)? This applies to the entire text.

Response:

Nomenclature was corrected

Comment:

Response:

We appreciate the reviewer’s comment and the opportunity to clarify this point. The selection of the test vehicle was intentional:

In Ecuador, the average age of the vehicle fleet is approximately 14 years. Therefore, the use of a ten-year-old vehicle reflects the typical condition of vehicles circulating in Guayaquil and ensures representativeness of the study.
A newer car was not selected because it would not adequately capture the real driving dynamics and emissions profile of the majority of the local fleet.
Regarding mileage, the selected vehicle had approximately 533400 km at the time of testing. We have now included this information in Table 1 for clarity.

The revised text in Section 3.1 (p. 5, lines 168–170) now explicitly explains the rationale behind the vehicle choice (p. 6).

Comment:

Response:

OBD nomenclature is changed to the correct OBD-II nomenclature used throughout the manuscript.

Comment:

Response:

We agree that the presentation of non-controllable variables in Table 2 was not sufficiently explained in the original version. Our intention was to acknowledge contextual factors (e.g., ambient temperature, altitude, fuel quality) that may influence vehicle performance, even though they were not directly included in the weighting or statistical analysis. To avoid confusion, we have revised Table 2 and its description.

In particular, the reference to octane number has been clarified: during all tests, the vehicle was fueled with 85-octane "Ecopaís" gasoline, the most common used in Guayaquil. We have updated the text (p.9) to explicitly state the fuel used and removed variables that were not relevant to the subsequent analysis.

Comment:

Response:

Corrected decimal notation in tables 8-11

Comment:

Page 19. The list of abbreviations is incomplete. There are many more terms in the text that should be included here.

Response:

We thank the reviewer for this helpful remark. In the revised version we have thoroughly reviewed the entire manuscript and expanded the list of abbreviations (p. 22) to include all technical terms used in the text. This ensures completeness and consistency for the reader.