Public-Private Partnership Transportation Investment and Low-Carbon Economic Development: An Empirical Study Based on Spatial Spillover and Project Characteristics in China

Round 1

Reviewer 1 Report

Authors examine " Public-Private Partnership Transportation Investment and Low-Carbon Economic Development: An Empirical Study Based on Spatial Spillover and Project Characteristics in China" seems interesting work and report some relevant results. but authors need to fix the following technical issues:

1. First, authors need to properly define the dataset, scale, and measurement. it's unclear whether longitudinal data was prepared.

2. Second, there are two dependent variables GC and CE, do they are part of the system, authors need to apply 2SLS or system method to deal with the endogenous issues.

3. in Table 6 and another table, the R2 is very high, indicating the presence of a trend in the variables, need to apply panel unit root to diagnose the trend and perform the estimation accordingly .

 

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript falls within the “Sustainability” journal’s aims and scope. The study evaluates the economic sustainability of PPP investment in transportation infrastructure in China. The research confirms the positive effects of transportation PPP investment on a low-carbon economy in China. Do the authors believe that their results can be extended to other countries or rather not due to the peculiarities of the Chinese economy?

 The abstract should be extended by taking into account the purpose and method of the research.

The introduction section does not provide the purpose of the work, its significance, and the eventual research hypotheses. What could be the relevance of this study from an international perspective? What scientific gaps in the international literature does this article fill?

Authors argue that “Most studies has confirmed the economic value of PPP and pointed that PPP has economic growth effect” referencing only three articles and merely about China. I would expect here some evidence from other countries around the world, especially that in the Discussion part, the Authors repeat that “On the basis of studies on the impact of PPP on economic growth, this paper innovatively adds carbon emission as a constraint condition to further explore the low-carbon economic effect of transportation PPP investment.”

The same concerns international literature dealing with other impacts of PPP on the economy and society (infrastructure quality and efficiency; employment, etc.). As concerns "few studies" which studied the relationship between transportation PPP investment and economic development from the  perspective of carbon emissions" I suggest Authors consider including additional publications, for instance, the following ones:

Anwar, A., Sharif, A., Fatima, S., Ahmad, P., Sinha, A., Rehman Khan, S. A., Jermsittiparsert, K. (2021). The asymmetric effect of public private partnership investment on transport CO2 emission in China: Evidence from quantile ARDL approach. Journal of Cleaner Production, 288, 125282. https://doi.org/10.1016/j.jclepro.2020.125282

Koppenjan, J. F. (2015). Public–Private Partnerships for green infrastructures. Tensions and challenges. Current Opinion in Environmental Sustainability, 12, 30–34. https://doi.org/10.1016/j.cosust.2014.08.010

Papajohn, D., Cui, Q., Bayraktar, M. E. (2011). Public-Private Partnerships in U.S. Transportation: Research Overview and a Path Forward. Journal of Management in Engineering, 27(3), 126–135. https://doi.org/10.1061/(ASCE)ME.1943-5479.0000050

 Below, please find some specific comments and suggestions that may improve the manuscript. 

40. „Public-Private Partnership (PPP), as an innovative mode” – The PPP phenomenon has been around for a long time, see, for example, Bovaird, T. 2010. A Brief Intellectual History of the Public–Private Partnership Movement, In Graeme A. Hodge & Carsten Greve & Anthony E. Boardman (ed.), International Handbook on Public–Private Partnerships, chapter 3, Edward Elgar Publishing. DOI: https://doi.org/10.4337/9781849804691.000. Perhaps, the authors meant PPP innovativeness in China.

 

41-43; 194-199; 205-207. When authors give some facts or information about the origin of data, they should use references to the source (e.g.,IPCC Guidelines for National Greenhouse Gas Inventories 2019; China National Standard “General Principles for Calculation of Total Production Energy Consumption”) – these are not present in the Reference list

 216-217: Is GDP calculated/expressed in nominal terms (current prices) or in real terms (constant prices)? It is very important as this research period covers the years from 2006 to 2018, and considering inflation, the results of Formula (1) may be distorted by the influence of prices on the value of GDP in the case of nominal GDP. Economic growth is measured in terms of the increase in real GDP.   

229-230: The same question as above; is capital input (fixed asset investment) measured in constant or current prices? If in constant prices, what year is the base?

248-250: Is transportation PPP investment measured in current or constant prices?

 112; 173  and 315-316: “The typical feature of PPP projects in China is that state-owned enterprises are the main body of social capitals” - I don’t understand this sentence; what does the term "social capitals" mean in this context? Social capital is differently understood, usually as a kind of social relations. I propose the term "social ownership". 

585: I would advise the Authors to avoid the term ”results suggest”, rather they confirm, show, etc.

There are no text references to specific tables (Table 1; Table 2)

I decided to not dig into mathematical formulas but they need checking.

I noticed some grammar mistakes; 49: "Most studies has confirmed" (have); 585-586: “The results suggest that: (1) transportation PPP investment markedly promotes the low-carbon economic development in China from 2006 to 2018” (present tense instead of past tense)

 The Sustainability journal's  Instructions for Authors highly encourage using DOI numbers (Digital Object Identifier). The DOI will help readers quickly locate documents listed in the References. The References should include the volume and issue of the journal (Eg., Stulz, R. The limits of financial globalization. The Journal of Finance. 2005, 60(4), 1595–1638. 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

now authors have improved the work