Review Reports

Round 1

Reviewer 1 Report

General: This is an interesting paper with a comprehensive analysis of the Chinese transport system with respect to technology trends and CO₂-emissions.

I am not familiar with the methods used and cannot comment on these. My impression is that the analysis is correct and well-rooted in the existing literature.

I am not familiar with the concept of ‘technological bias’ either. I tried to understand the difference between the bias of technological change and exogenous or ‘neutral’ technological change, but I failed. The two types of changes are represented in Eq. 5 (MTC and BTC), but I do not understand the meaning of the variable ‘S’ in this equation and hence not the equation. According to lines 220&221 ‘S’ stands for desirable output, but my impression is that from line 226 onwards ‘S’ has a different meaning (if this is true it would be better to use different symbols). Line 226 suggests that ‘S’ would mean environmental efficiency (ρ), but S is a function of both input and output factors, so I wonder whether it would only indicate environmental efficiency. Can you give an explanation of ‘S’ in the equations?

I have the general question why the authors are only interested in the bias of technological change and not in the full technological change? It is true that they give figures about both changes, but the aim of the paper is limited to the bias.

 

Some specific comments and questions:

Line 63: “Green TFP implies” looks like the beginning of a definition of Green TFP. However, the remaining sentence does not define it but seems to describe what happens if Green TFP increases. Because of the central position of Green TFP in the paper, it is advisable to include a definition.

In line 221 ‘x’ seems to relate to DMUs, ‘y’ to inputs and ‘b’ to undesirable outputs. But in line 228 and later in the paper the meaning of x and y changes: ‘x’ then relates to inputs and ‘y’ to desirable outputs. Is there a mistake in presumably line 221?

In equation 4 in the part that indicates the TC, the two denominators are identical. I suppose that in one denominator x^t, y^t, b^t should be x^t+1, y^t+1, b^t+1.

Table 1: what do the minimum and maximum values mean? Are these the lowest and highest values of the provinces? What is the year(s) of the figures in the table?

According to Table 2 the exogenous technological change (MTC) was below 1 in all provinces. Does it mean that the exogenous trend of technology was negative? This would be opposite to the general technological trend. Is there an explanation for this?

Figures 1 and 2: are these the averages for the Chinese provinces?

Line 433-434: “divided by” can have the alternative meaning of taking the ratio (BTC/IBTC and BTC/OBTC). To avoid confusion another wording is preferred (“split up by”, “broken down by”).

Table 4: what does mean “trans_added”? Is it identical to ‘value added’? And what is the meaning of the figures in the CO2-producing column? If this is high (like in 2010), does it mean a high increase or a high decrease of the CO2-emissions compared to the desired output?

Lines 542-544: “in reality, these regions often increased emissions rather than producing more desirable output (trans_added) in 2005–2017, resulting in a negative influence on green productivity growth.” Can this be derived from Table 6, or is this information added by the authors?

Line 591 and after: You talk about “transportation models” when you mean ‘transportation modes’.

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper examines biases relating to technological changes in sustainable development of China’s transportation industry during the 2005-2015 period and influencing factors. This is an interesting and well-written paper. The reviewer has few minor comments for improvement as follows:

Eq 3 and 4 does not seem to align. Given the same term on the left-hand side, the right-hand terms should be the same. However, it is not the case. Note that there are two terms S_t+1_k(xt,yt,bt) on the denominator of Eq 4. Should one of these be S_t+1_k(xt+1,yt+1,bt+1). This would affect the following equations. Please clarify.

The authors are encouraged to improve discussions about the reasons for differences between regions (instead of mentioning the differences). This will increase the value of the paper.

Abstract: please define K-using and L-saving.

Eq 3: please define S_t_k. The term S in Eq 2 does not have the superscript “t”.

Table 2 – it may be worth adding the standard deviation, in addition to the mean values, to show degrees of variations during the study period.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf