A Comparison into the Factors Affecting Urban Rail Systems: Local, Express, and High-Speed Rail in Tunnels at a Great Depth in a Metropolitan Area
Round 1
Reviewer 1 Report
The authors propose a mode choice model for evaluating user preferences among different railway systems.
First of all, I reckon that the authors should modify the term “mode choice” into “system choice” since according to the traditional literature (see, for instance, Domencich & McFadden, 1975; Ben-Akiva & Lerman, 1985, Cantarella, 1997; Cascetta, 2009) term “mode choice” is generally adopted for describing user preferences among private car, pedestrian mode, public transport systems, and so on.
In this case, users have already chosen to travel by public transport and, therefore, they have to choose which public transportation system want to use.
In some cases (for instance, in the case of integrated public transport fares), the choice among different public transport systems is a sort of path choice model.
However, I reckon that the authors should analyse the topics in detail by providing appropriate examples in the literature and better arguing their choices.
Since the analysed context compares some level-of-service parameters such as the passenger behaviour on the platform, I reckon that the authors should provide proper references with related analyses concerning:
- passenger behaviour on railway systems (on-platform and pre-platform behaviours)
- passenger behaviour at rail platforms (FIFO vs RIFO approach)
- interaction between travel demand and railway services
- contribution analysing the relations between passenger flow and dwell times
Finally, detailed formulations concerning times affecting passenger choices in the railway systems may be found by analysing contributions dealing with the adoption of the Merry-Go-Round paradigm.
Author Response
Thank you for the valuable comments. We revised the manuscript as attached.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The article discusses the influence of travel times and out-of-vehicle times in the choice between some types of rail transport in the Seoul metropolitan area: the subway "local train X express train" and the "express train X the new GTX train that will be built at a depth of 50m”. The usual survey methodology is employed. The subject of the article is interesting and has been little explored in the literature, but the content needs to be improved in some aspects, for a new evaluation. The authors should clarify the following points:
1- The current rail transport system (particularly subway line 9, local and express) and the survey needs to be better explained. Is the line section in Figure 2 real or hypothetical?
If it is real: How were the respondents chosen? Randomly? Only users of the line section indicated in Figure 2? Are users whose destinations are intermediate stations excluded from the survey? What proportion of respondents uses the local train? And the express train?
If it is hypothetical: How were the respondents chosen? Randomly? What proportion of respondents uses the local train? And the express train? Note that if the line section is hypothetical the survey actually appears to be “stated preference” (In Conclusions we see: “revealed preference survey”).
Regarding the line section in Figure 3, the sentence “Many respondents stated that they would use the railroad” seems meaningless. What kind of railroad? Isn't this survey just for express train users?
How was the online survey carried out? How were respondents chosen? What proportion to the total?
Is the group of respondents in the “local x express” survey the same as in the “express x GTX” survey? Is the number of respondents the same in the 2 groups?
I suggest reviewing the text so that all these issues are clearer for the reader.
2- It is not clear the usefulness of surveying data on “car ownership”. There is no reference to it in Tables 5 and 6. In Line 168, the sentence “In the case of the car ownership…” is also not clear. It needs to be better explained.
3- To improve the reader's understanding, it would be better to avoid using terms such as “ordinary train” or “general railroad”. It is best to always specify whether it is “local” or “express”.
4- Formula 4 and the following on Line 248 need to be revised.
5- It is more usual to number all Formulas as follows: (1), (2), etc...
6- In Tables 5 and 6, in the first line: “Wals” would not be “Wald”?
7- On Line 367, the abbreviation “SP” was not expanded. I believe it is “stated preference”. Better to use the expanded term.
8- References and citations are not in accordance with the journal's standard. References must be numbered in order of appearance in the text and listed individually at the end of the manuscript. In the text, reference numbers should be placed in square brackets [ ], and placed before the punctuation; for example [1], [1–3] or [1,3]. This implies that all citations and references need to be changed.
9- I believe that the apparent small sample size is a limiting factor for the research and this should be informed in the Conclusions.
Author Response
Thank you for the valuable comments. we revised the manuscript as attached.
Author Response File: Author Response.pdf
Reviewer 3 Report
Very interesting study. Nevertheless, I think that you can improve it about three aspects.
- The sections must be re-structured. After literature review, it is necessary a section about the objectives of study. These objectives stablish the framework to design the survey and to identify analysis methodologies. After Objectives section, usually there is the section of ‘Methodology and data’ to explain structure of survey and statistical analysis.
- Sample size. It is necessary a discussion about the survey sample size and confidence level in order to analyse the statistical significance of sample.
- It is possible improve references and literature review with authors out of South Korea.
Author Response
Thank you for the valuable comments. we revised the manuscript as attached.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The current version of the paper has satisfied all my previous observations
Reviewer 2 Report
The authors made the indicated corrections and the manuscript was improved, being ready for publication.
