Digital Twin for Urban Planning in the Green Deal Era: A State of the Art and Future Perspectives

Round 1

Reviewer 1 Report

The work is framed thematically in the proposed Special Issue. It is original and well founded. It offers potential for publication. In fact, the abstract, the introduction, a good part of the materials and methods and the results are fine. Without a doubt, his contribution stands out on a theoretical level.

However, the whole analysis presents a problem. A very heterogeneous set of cities taken as examples are selected and it is not explained why they are all considered equally. The proposed interpretive model cannot be applied with the same criteria in Singapore or in an average European city. Nothing is indicated regarding the establishment of typologies of analysis. The city category is assumed universally, identically, which is a mistake.

This problem arises in the Materials and Methods methodology, and conditions the entire Discussion and Potential Limits section. This section should be completely reformulated. Similarly, the conclusions are unsatisfactory. This is a very general assessment, which does not delve into the internal differences in the character of cities, by size and depending on their governance, and location.

Author Response

Dear Reviewer,

Thank you very much for your review and for considering the work as a whole to be good and subject to publication. I also apologise for the time lapse between the first and second review, but unfortunately, I contracted covid19 with symptoms.

I wanted to point out a few points that explain the paper in its structure and purpose.

The case studies are not considered identically but it is the categories of interpretation aimed at a summary table that are the same. I agree with you that in terms of geographical location, levels of governance and political structure, urban form and so on, we are talking about different cities and contexts. Specifically, my study analyses the type of DTs, the purposes and the instruments deployed, trying to highlight the limits and potential of the projects themselves as far as it is possible to extract from the selected papers.

I do not enter into the merits of the political-governmental conditions of the city, the reasons that directed the development of the Project, the specific composition of the Partners or the type of urban structure involved. This is either already accounted for in the papers themselves (to which I refer in the text for a greater understanding of the individual aspects of the case studies) or would probably need more in-depth research in other sources. This is my intent for Helsinki, which will be a case study for the doctoral research, but I have no way of dealing with such extensive research for all the case studies, which is beyond the scope of the type of work as I have set it up.

In the text, however, the criteria for choosing the case studies are made more explicit. Furthermore, I have tried to make the results obtained more comprehensible, which are not quantitative but rather critical interpretative and synthesis oriented to feed the work of reasoning, discussion and conclusion on the topic DT and urban planning.

I summarised the notes by merging them with the text as requested by the editors, made minor changes to the English, and added some specifications throughout the text where required also by the other reviewers or deemed necessary for greater clarity of content.

Thanking you for your suggestions and hoping to have clarified any doubts you may have about the work I have done, I send you my best regards.

Thank you for your attention,

Giorgio Caprari

Reviewer 2 Report

The paper is very well structured and its contents are logically organized. The paper's main goal is clear and the mentioned methodology is adequate concerning the expected results. The core issues regarding the research topic weakness are well identified, but the referred problem about socio-cultural subjects within DT could be a bit more developed because it is a very important step to consolidate in this area of knowledge. In addition, this is in line with the author's worry about the correlation between qualitative and quantitative approaches when considering the role DT in urban planning. These comments I make here can be a bit better explored by the author by adding one or two more paragraphs in the discussion section.

Author Response

Dear Reviewer,

Thank you very much for the review, the suggestions provided and the good overall judgement. I also apologise for the time lapse between the first and second reviews, but unfortunately, I contracted covid19 with symptoms.

I agree that DT can and should make a significant contribution in the enhancement of socio-cultural aspects by accelerating the transition towards a real participation of citizenship in urban transformation processes. This tool, in addition to new forms of co/geo-design, can innovate the modes of communication between the actors of the territory for greater inclusivity in public choices and propose new forms of virtual experience of the city and cultural heritage, giving voice to local knowledge. In this regard, as suggested, I tried to add a few sentences between the discussions and the conclusions.

With regard to my worry about the quantitative approach ('indicators') capable of representing all urban phenomena not by representing them but by abstracting them numerically I have tried to add a few sentences. I believe that a good compromise is the integration of traditional methods and GIScience tools. Combined they might constitute a real advancement in the field of urban and spatial planning disciplines at the various scales, from geo-spatial analysis to design based on integrated, punctual and trans-disciplinary knowledge.

Hoping to have made significant and clear updates to the text, I send my best regards.

Thank you for your attention,

Giorgio Caprari

NB: On this critical and theoretical reflection, I will try to write another article more focused on my thought of a necessary integration of analogical and digital. In this article, I believe I have sufficiently explored the discursive parts, which if extended would unbalance the internal weights of the article.

Reviewer 3 Report

Digital twin is one of the important themes in future urban planning approaches, and I think this study is very valuable because it compares prior examples and specifies future issues. I think the following points should be revised to show the outcomes of this study more clearly.

1) In the Introduction, the differences between the previous study and this study should be more clearly described.
Existing studies have provided conceptual discussions and discussions on technology and architectural systems. However, the issues involved in implementing digital twins in the real world and the shortfalls from current efforts to the goal of the ideal systems have not been sorted out. I think that the value of this study is that it clarifies these points through comparison of actual case studies.

2) It is unclear why six case studies were selected for this study.

3) The discussion in Chapter 4 is very important, but the relationship between the results of the case study analysis in Chapter 3 and what is organized in Chapter 4 is unclear.
In particular, it should be clarified which case study analysis results led to the three definitions of DT (a, b, c) and the three issues facing DT today (a, b, c) shown in Chapter 4.

4) Regarding Figure 3, I could not see the Dublin image.

Author Response

Dear Reviewer,

Thank you very much for the review and the good overall evaluation. I also apologise for the time lapse between the first and second review, but unfortunately, I have contracted covid19 with symptoms.

For the purpose of clarity, I will try to answer you in points following your approach:

1) As suggested, I tried to add one or two periods (e.g. at the end of the introduction) that clarify the advancement in the cultural debate on the topic, which goes beyond the mere notion and technological construction of the digital product but starts a critical synthesis and reflections about the selected DT projects.

2) In this case, I have made the selection criteria for the six case studies more explicit (section 2.3). I mean that these are case studies that are well represented in scientific articles that are accessible in open source format and that, due to their type, provide an overview of the various experiments on an international level.

3) As suggested, I have tried to improve paragraph 4 by creating connections between the points summarised and the cases analysed and by adding some useful sentences to clarify the logical steps in the text.

4) Thanks for the suggestion; I had incorrectly formatted the image. You should now see it in full.

Hoping to have made significant and clear updates to the text, I send my best regards.

Thank you for your attention,

Giorgio Caprari

Round 2

Reviewer 1 Report

The main requested improvements and revisions have been introduced. The article must be published