Track Deterioration Model—State of the Art and Research Potentials
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript presents an overview of the state of the art in railway track deterioration modelling (TDM) with focus on ballast (track geometry) degradation, rail surface wear and fatigue. The present TDM approaches proposed by TU Graz and SBB are refined by improvements in considering of rail surface wear and rolling contact fatigue, traction energy, and short-wave effects. The research has a great potential due to its direct relation to LCC analysis and thus infrastructure, operation mode, rolling stock design improvements. The manuscript topic fits well to the scope of the Journal. It is well structured. The conclusions correspond to the research done.
Nevertheless, there are some unclear points that could need some additional explanation/revisions according to the comments:
1) It is unclear what track condition (or time moment in the lifecycle) is considered for Eq. (1). Is it for new track after renewal or some average within the whole lifecycle, or may be cost calibration factors cn depend on it.
2) The term D7 (Damage that leads to track renewal) has some implicit relation to the Life Cycles of track components (ballast, sleeper and rail) that have very different lifetimes. But the term is actually proportional to D1. Is the term not redundant?
3) The Table 3 presents ballast bed stiffness variation for the cases from bad to good subsoil. It will result in high P2,S values for good case and low loading for bad one. But the deterioration (track geometry) is higher for the bad subgrade. Are the calibration parameters cn constant for all the cases?
4) The influence of the maintenance tolerances is not clear. Could the total joint angle serve as a parameter of the track condition?
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsIn the current manuscript, the authors attempted to review the state of the art in railway track deterioration modelling and outlines research potentials in this domain. The main focus lies on ballast degradation and rail surface wear and fatigue and its description in an empiric analytic wear formula. The basis for discussion is the wear formula of the Graz University of Technology. While the track deterioration model (TDM) demonstrates effectiveness, enhancements are sought, particularly with regard to adjusting track parameters that vary across railway networks. Further exploration aims to refine the description of rail surface wear and rolling contact fatigue (RCF), incorporating factors such as traction energy and short-wave effects, and adapting mathematical functions such as the t-Gamma function.
The topic of the paper is interesting and worthy of investigation. I have carefully read the paper and believe that it can be published after some major modifications as follows:
- In the abstract, please highlight why it is important to investigate on track deterioration modeling (TDM), what are its benefits, limitations and assumptions, in detail.
- It is recommended to add a new section and identify different types of creep forces between the rail and wheel of the vehicle. For more information, read and discuss the following relevant article: https://doi.org/10.1016/j.scient.2012.10.028
- The quality of some figures is very poor which is not suitable for online publication. Please, if possible, reproduce such figures, for example, Fig. 8.
- Please clarify that what kind of damage mechanics modeling are suitable to model the wear behavior of wheel-rail contact.
- In reality, different kinds of wheel or railway profiles are manufactured. Does the current review study cover all kinds of profiles?
- The literature review is not accurate enough to reflect the importance and show the real applications of the considered problem. It is highly recommended to enrich this section by discussing more relevant works regarding the rail modeling and vehicle dynamics. The following articles in the literature are suggested to be included and discussed.
- DOI: 10.22055/JACM.2021.38826.3290
- More discussions on the presented results are needed to present the major outcomes of the present study.
- The conclusion section should be rearranged to express the main concluding remarks of the present work.
Comments on the Quality of English Language
In the current manuscript, the authors attempted to review the state of the art in railway track deterioration modelling and outlines research potentials in this domain. The main focus lies on ballast degradation and rail surface wear and fatigue and its description in an empiric analytic wear formula. The basis for discussion is the wear formula of the Graz University of Technology. While the track deterioration model (TDM) demonstrates effectiveness, enhancements are sought, particularly with regard to adjusting track parameters that vary across railway networks. Further exploration aims to refine the description of rail surface wear and rolling contact fatigue (RCF), incorporating factors such as traction energy and short-wave effects, and adapting mathematical functions such as the t-Gamma function.
The topic of the paper is interesting and worthy of investigation. I have carefully read the paper and believe that it can be published after some major modifications as follows:
- In the abstract, please highlight why it is important to investigate on track deterioration modeling (TDM), what are its benefits, limitations and assumptions, in detail.
- It is recommended to add a new section and identify different types of creep forces between the rail and wheel of the vehicle. For more information, read and discuss the following relevant article: https://doi.org/10.1016/j.scient.2012.10.028
- The quality of some figures is very poor which is not suitable for online publication. Please, if possible, reproduce such figures, for example, Fig. 8.
- Please clarify that what kind of damage mechanics modeling are suitable to model the wear behavior of wheel-rail contact.
- In reality, different kinds of wheel or railway profiles are manufactured. Does the current review study cover all kinds of profiles?
- The literature review is not accurate enough to reflect the importance and show the real applications of the considered problem. It is highly recommended to enrich this section by discussing more relevant works regarding the rail modeling and vehicle dynamics. The following articles in the literature are suggested to be included and discussed.
- DOI: 10.22055/JACM.2021.38826.3290
- More discussions on the presented results are needed to present the major outcomes of the present study.
- The conclusion section should be rearranged to express the main concluding remarks of the present work.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThis paper review provides an overview of railway track deterioration modeling and outlines research potentials in this domain. The main focus lies on ballast degradation and rail surface wear and fatigue and its description in an empiric analytic formula. So far, the paper includes new contributions. However, a number of issues in the manuscript are expected to be solved. Besides, there are some suggestions and questions that should be addressed.
Please explain why this paper mainly focuses on the Track Deterioration Model. What are the advantages of this method over others?
How has the independence of the D terms been proven? Please explain clearly the presence or absence of each D parameter in the estimation.
How the frequency of loads is considered when dealing with fatigue loads, specifically for D2 and D4 terms?
The introduction section is too brief and lacks a clear description of the methods used in the field. Please refer to the following sources:
Experimental study and discrete element analysis on lateral resistance of windblown sand railway, 10.1016/j.trgeo.2022.100740
Effects of Wheel Surface Defects on Ground Borne Vibration, 10.12700/APH.19.6.2022.6.10
Effect of shape of concrete sleepers for mitigating of track buckling, 10.1016/j.conbuildmat.2021.123568
Effect of Sleeper-Ballast Particle Contact on Lateral Resistance of Concrete Sleepers in Ballasted Railway Tracks, 10.3390/ma15217508
Dem modeling of crushable grain material under different loading conditions, 10.3311/PPci.17948
It would be more appropriate to include a paragraph at the end of the introduction section that outlines the structure of the paper.
The quality of Figure 8 needs improvement, and all parameters should be defined in greater detail.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsThe article focuses on the Trak Degradation Model (TDM), its current state of development and its potential for future enhancement. This article summarises previous research on which the current state of the TDM is based. Given that the methodology itself involves many technical phenomena, the article itself is also quite extensive. Unfortunately, the paper is not entirely consistent in the details of the individual sections, but this is understandable given the scope of the subject matter. I would prefer to keep some parts more general and then focus on individual chapters in separate follow-up articles.
Overall, I found the article interesting, providing a useful overview of previous research and publications. The paper overall provides a good overview of the TDM methodology developed by the Technical University Graz. Then, in Chapter 3, the possibilities for further enhancement of the model are discussed. There are many open questions; Fig. 11 demonstrates the number of questions. In general, the methodology presented is directed towards the development of general statistical models to include and assess the influence of specific design, operation and maintenance parameters.
Specific comments on the text of the article:
In the introduction, I recommend adding the information that the presented methodology is mainly focused on the ballasted track structure. Some parts will generally be applicable to ballastless track; again, I recommend mentioning which parts they are.
The chapter numbering is not formally correct. For example, chapter 2 has a rather extensive and important introductory section, followed by chapter 2.1. I recommend modifying the caption system throughout the article.
Ch. 2: The coefficients c1 to c7 formally have units, as does Dn. These units correspond to the conversion to cost/km for CvehR,S. I recommend describing this in general terms.
Ch. 2.1.2: Of the maintenance work on the track bed, only tamping is meant (as the usual method in Austria; other methods of track geometry adjustment are not mentioned). Also, ballast cleaning is not mentioned.
Chapter 2.1.3: When talking about dynamic forces, we should generally refer to forces caused by vehicles and track parameters, both geometric and other, e.g. stiffness changes. P2 force is essentially an impact force, so one parameter is selected. This fact should be discussed in the paper. Formula (4) is originally intended for a jointed track, see angle 2alpha. I therefore recommend that a note on welded track and insulated joints be inserted immediately.
Chapter 2.1.3, Table 3: C values for the subsoil are given, however for the level of the bottom surface of the sleeper on the track bed, the values are usually higher; this should be explained here in more detail (e.g. very good sleeper substructure approximately 0,3 N.mm-3)
Chapter 2.1.3, Figure 1, it should be mentioned that the influence of the parameters in equation (5) is not linear, so the 25% variation is only indicative to give an impression.
Chapter Superlinearity - Exponent 3, according to ORE [6], is common for D1 and D2; I recommend including it as a separate numbered chapter, generally before chapters 2.1 and 2.2.
Chapter 2.2: I recommend inserting the explanation of equation (12) for forces P1 and P2 again as a general introduction before chapter 2.1.
Chapter 2.4 Instead of Tables 4 and 5, which are extensive, it would be more appropriate to provide a scheme (figure) and a description of the parameters.
Section 2.4.4 describes the rail damage/wear mechanism in general. I recommend that this section be included as an introductory section in Section 2.4 with the comment that the Tgamma approach is specifically used for the D4 factor, which is then described in later sections.
Minor formal comments:
The Aeff of equation (20) coincides somewhat with the Aeff of equation (9)
In equation (23) there is a unit mistake in the third line.
Pg. 17: HC is introduced as an abbreviation, yet it is only used once further in the text, I would prefer not to introduce the abbreviation
Pg. 18, line 571: Tgama is not in italics.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsAccept.
Reviewer 3 Report
Comments and Suggestions for AuthorsAccept.
