PONE-D-22-35314Modeling Barcelona sidewalks: A high resolution urban scale assessment of the geometric attributes of the walkable networkPLOS ONE

Dear Dr. Clua,

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1) Text is too long. If possible try to shorten it without losing quality;

2) In the webpages access date needs to be added;

3) There are very few scholarly articles cited in the text, and very many websites and Spanish-language items. Please add some/any foreign publications;

4) Some typos in the text, e.g. line 595 and other;

5) Some figures are unreadable e.g. 12 and 17;

6) It would be nice to see a table showing the data reduction during the workflow in terms of quantities (e.g. numbers for input data polygons/lines, node count, segments (etc.) before/after aggregation at certain steps in the process, and processing time needed);

7) It would also be nice to see the actual code that was used to produce graphics;

8)  A comparison with other data sources or on-site observations (examples/ground truth) could help to better critically reflect the workflow results and illustrate where the model/workflow resulted in errors, ambiguities, or inaccuracies, either due to data or method used.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: N/A

Reviewer #3: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: I would like to congratulate the author to revised and improve the quality of the manuscript. The manuscript is now written very well and the analysis carried out in this research is new and the results represents the actual study performed.

Reviewer #2: Review of the article “Modeling Barcelona sidewalks: A high resolution urban scale assessment of the geometric attributes of the walkable network”

In this paper authors presents a method of modeling the street network from the perspective of foot traffic, beyond the vehicle-focused street centerline representation approach in transportation research. A scalable method to extract the centerlines of the complete walkable urban area from its polygon representation at a one-meter resolution is discussed, using open-source tools. evaluate the betweenness centrality in a spatial directed graph, the process is applied to the study of the ‘walkable Barcelona’, focusing on three key parameters: 1) the street width, 2) the longitudinal slope, and 3) the crosswalks connecting the sidewalk platforms. The results identify the uneven distribution of these parameters within a complex urban fabric, and the high-resolution cartography allows the identification of critical areas within the network, introducing future lines of research and applications of the model. This is especially relevant considering the increasing awareness of citizens and the urban agendas worldwide, aimed at improving and widening the sidewalk infrastructure that supports local activity in cities

General thoughts

The article presents interesting research and very well prepared. Test procedure is clear and justified, study data are rightly chosen and sufficient, authors correctly described the study. It is important that the test procedure can be reproduced by other researchers. The following detailed comments are intended to correct some of the shortcomings of the article.

Detailed comments

Text is written in a logical and thoughtful way, creating a coherent whole, in accordance with the writing regime of scientific paper (IMRaD). The method of presentation, comprehensive introduction and very interesting and thoughtful practical examples deserve praise. Below a comments for corrections:

1) In my opinion text is too long in some way it might be shorten which will affect on its better reception

2) In the webpages access date needs to be added

3) There are very few scholarly articles cited in the text, and very many websites and Spanish-language items. Please add some/any foreign publications

4) See remark 2, regarding references

5) Do the authors believe that a similar type of research can be applied in geography and tourism to trail research? Please refer into the text adopting below positions:

a) Chwedczuk K, Cienkosz D, Apollo M, et al (2022) Challenges related to the determination of altitudes of mountain peaks presented on cartographic sources. Geod Vestn 66:49–59. https://doi.org/10.15292/geodetski-vestnik.2022.01.49-59

b) Csapó J, Wetzl V (2016) Possibilities for the Creation of Beer Routes in Hungary: A Methodological and Practical Perspective. Eur Countrys 8:250–262. https://doi.org/10.1515/EUCO-2016-0018

c) Mionel V, Mionel O (2016) Cycle tourism in Olt county, Romania. (Re)discovering potential of history and geography for tourism. Amfiteatru Econ 18:913–928

6) Some typos in the text, e.g. line 595 and other

7) Some figures and unreadable e.g. 12 and 17

Text might be accepted for a publication after improvements.

All the best and stay safe

Reviewer #3: General Statement:

The paper demonstrates a detailed implementation workflow for processing urban spatial information to extract sidewalks in Barcelona as a case study. These are used to generate pedestrian network information such as shortest paths, network costs for different edges and segments or summary metrics for different distributions. The results are generally interpret, listing benefits of the implementation and several opportunities for application.

1. The strengths of the paper are its nice graphics and the holistic and good explanations for taking different routes and combining different tools and software along the way, including the descriptions of dead ends. I am no expert in network or topology processing, so I cannot comment on the overall significance or novelty of this papers contributions, particularly for the sub-field of pedestrian network extraction. The short literature review suggests that there is limited comparable work available. That said, the results and process look quite polished, the discussion is reflected and comprehensive, and I would argue that the biggest value for readers lies in the practical implementation and the decision tree that is described in the text. The text is easy to follow and overall well written.

2. Unfortunately, the decision tree for the workflow is not shown as a figure and the practical implementation can only be followed using the text. Figure 2 is a good first overview of the overall workflow, but it is linear, whereas in the manuscript, positively, several dead ends are described, software or data limits, alternative ways or sensitivity checks being done that are not visible in Fig 2. To someone who wants to transfer the workflow to another city, a decision tree would be quite helpful, indicating these options and alternative routes for adaption (e.g. in case of data availability and other changing parameters).

3. It would also be nice to see the actual code that was used to produce graphics. Given that the authors mention Pandas, SciPy, PostGis (etc.) and automatic processing (L.889), I would expect that some kind of Code-Notebook is used (e.g. Jupyter) – perhaps the authors could share these Notebooks or the Code as Supplementing Material. This would also allow readers of the paper to transfer the shown implementation more easily to other cities, which from my point of view would be the most critical contribution.

4. Performance of the data processing appears to play a crucial role in deciding which tools/software or methods were chosen for the various parts of the workflow. It would be nice to see a table showing the data reduction during the workflow in terms of quantities (e.g. numbers for input data polygons/lines, node count, segments (etc.) before/after aggregation at certain steps in the process, and processing time needed).

5. Given the immense data processing being done, I found the discussion of results a bit shallow – I could imagine more comparison with external or existing data sources (e.g. in terms of quality or application), or perhaps a discussion of the impact of this new data on Barcelona city policy/planning – although I understand if this is not possible, given the currently already quite lengthy manuscript. A comparison with other data sources or on-site observations (examples/ground truth) could help to better critically reflect the workflow results and illustrate where the model/workflow resulted in errors, ambiguities, or inaccuracies, either due to data or method used.

I think both of the important suggestions (1. notebooks/code as supplementary materials and 2. workflow decision tree) should be possible with minor modifications or limited additional work. I added a number of minor formal suggestions and a few more specific questions below. I suggest Minor revisions.

Specific Questions:

LL. 477: The medial axis explained here and used later for the network, especially for larger plazas and areas, appears to follow through the center. Wouldn’t pedestrians, who are trying to find the shortest path, walk along the edges of plazas (etc.), instead of walking through plazas based on the nodes located in the middle?

LL. 558: How long were the longest segments? Could they also pass a ridge? (peak in the middle, e.g. where start and end of the segment would be the same height, falsely leading to a 0% slope)

LL. 733: This may be related to my absence of network topology knowledge, but perhaps you could explain why forward and backward directions needed to be analyzed separately. I would expect that a forward weight on a slope uphill is simply inversed on the reverse downhill direction. I wonder why a separate computation is necessary.

L. 866: „The method“ – later on, you use „the model“ (L. 877). I am not picky about these terms. Generally, I would suggest to use ‚workflow‘, since you combine many individual methods in a specific way for the Barcelona case study, and transfer to other cities is not shown. In any case, I would be consistent and clearly distinguish what you mean with model and method, if both terms are used.

Specific comments:

L. 37: Remove “around the world”

L. 81: “[…] by A. Svetsuk (17) [...]” - Remove "A. "

L. 135: Replace “Wien” with Vienna.

L. 430: It should be briefly described what „straight skeleton“ (and other specific network topology terms) means.

L. 564/565: This sentence is difficult to understand. What is the ‘densification step’, and why are two steps necessary instead of tuning parameters of the first step?

L. 595: The equation is not formatted correction/not legible.

L. 587/688: Figure 11 shows nodes, and random colors of nodes, but the weight is not shown – perhaps add a legend for the width of lines with unit of measurement.

L. 717/718: Sentence is difficult to read, there seems to be a missing word between discarded and aggregating.

L. 744: „linestring layer“ seems to be a specific term related to a specific software, perhaps describe more generally.

L. 807/808: “the fact” used twice.

L. 838: This sentence is difficult to understand. Percentage sign missing?

L. 935: “The most used sidewalks” – insert “likely” (e. g.), to indicate that this is not based on observation, but projected data from your workflow

Formal: All Internal references are broken and point to Zotero online links.

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Reviewer #1: No

Reviewer #2: No

Reviewer #3: Yes: Alexander Dunkel

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Modeling Barcelona sidewalks: A high resolution urban scale assessment of the geometric attributes of the walkable network

PONE-D-22-35314R1

Dear Dr. Clua,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Claudionor Ribeiro da Silva

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: All comments have been addressed

Reviewer #3: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #2: Yes

Reviewer #3: Yes

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: Yes

Reviewer #3: Yes

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4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #2: Yes

Reviewer #3: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #2: Yes

Reviewer #3: Yes

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6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #2: (No Response)

Reviewer #3: The new Figure 3 turned out very good for summarizing data reduction along the workflow

I appreciate the authors answers to my previous questions.

I think the paper can be published in its current form. I still think that publishing the code alongside would be critical, particularly since you intent publish in PLoS and as the process is otherwise hard to replicate, but leave this decision to the editors. There are some remaining typos which I have listed below.

LL. 327: what is “the plos geometry”?

LL. 363 “[…] because include the information […]”: seems like a word is missing

LL. 524 “[…] this degree 2 nodes to […]” something seems wrong with this sentence, what does “2” mean here?

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #2: No

Reviewer #3: Yes: Alexander Dunkel

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