Preliminary Tests of a Hybrid Cable Splice (Synthetic–Metal) to Innovate Timber Harvesting in the Mediterranean Forestry Sector

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The work has attempted to modify existing materials used for timber logging via experimental and on-field approaches. Majorly, there is a need to proofread the manuscript and change Table 22 in Line 243 to Table 2.  

Comments on the Quality of English Language

There is a need to proofread. 

Author Response

Comments and Suggestions for Authors 

The work has attempted to modify existing materials used for timber logging via experimental and on-field approaches. Majorly, there is a need to proofread the manuscript and change Table 22 in Line 243 to Table 2.   

ANSWER Thanks for the review and the opportunity to improve our work. And thanks for identifying this typo error. The Table is now numbered correctly as Table 2 

Comments on the Quality of English Language: there is a need to proofread. 

ANSWER the whole document went through careful proofreading, further typo errors or non-elegant sentences had been identified and corrected accordingly.  

We attach the manuscript with track change of corrections.

Reviewer 2 Report

Comments and Suggestions for Authors

I appreciate the authors’ effort to writing the research paper. The subject of the article is interesting. 

I think this paper could be major revision, since it needs editing (description of field study site and base machine in method, compare the steel, polyethylene, and hybrid cable durable in discussion with previous studies). In particular I suggest also completing the discussions, with more detailed comparisons with previous studies.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

I appreciate the authors’ effort to writing the research paper. The subject of the article is interesting. 

I think this paper could be major revision, since it needs editing (description of field study site and base machine in method, compare the steel, polyethylene, and hybrid cable durable in discussion with previous studies). In particular I suggest also completing the discussions, with more detailed comparisons with previous studies.

Author Response

REVIEWER I appreciate the authors’ effort to writing the research paper. The subject of the article is interesting. 

I think this paper could be major revision, since it needs editing (description of field study site and base machine in method, compare the steel, polyethylene, and hybrid cable durable in discussion with previous studies). In particular I suggest also completing the discussions, with more detailed comparisons with previous studies.

ANSWER We thank the reviewer for the time dedicated to evaluate and improve our study. We agree that the discussion needed a comparative analysis with the (few) similar studies and was integrated accordingly. Regarding the description of the field study site and base machine we just provided some additional info. In fact, each forest company equipped with the splice used it for several months according to their business schedule and in different work sites. As a consequence it was not be possible to describe in detail all the harvesting areas where each of the involved contractors operated. The unique reference available and provided in table 3 are the parameters that we considered relevant and reliably reported by the companies: avg winching distance, main hauling direction (up or downhill) and presence of stones on the ground. 

-- COMMENTS FROM PDF --

REVIEWER Introduction needs revision and better investigation of the overall contextualization of the topic.

ANSWER The introduction had been revised accordingly, also with the inclusion of additional references.

REVIEWER Lines 227-236 Please write more detail information.

ANSWER The description of the factors listed in the daily report had been integrated.

REVIEWER The results are confusing. I could not understand your results. Please add the statistical analysis.

ANSWER The results section had been revised. A statistical analysis is not possible due to the low number of replications per each treatment (each company using the hybrid splice for several months was a single replication of the test). As described in the manuscript, we planned a more structured experimental design with the involvement of a larger number of companies. But these committed to fill the daily report for free (compensation was the synthetic cable with splice provided to them), thus not all of them filled the report consistently. In any case, given the structure of the study that requires long time on companies working in commercial hauling, to collect a dataset large enough to perform a real statistical analysis would be a challenge even having a dedicated budget to contract forest companies.

REVIEWER This part is too short (Laboratory results).

ANSWER The section had been integrated with some more detail

REVIEWER Table 2. Do you have the effect of rope diameter on resistance? I would like to know what hybrid rope size is better than steel and polyethylene.

ANSWER This is a very good point. The comparison of diameters is relevant both during the manufacturing of the splice and in terms of performance and resistance. Unfortunately, at the moment we focused the study on two pre-defined sizes (16+14 mm on skidder and 14+12 on farm tractors). We will include this comparison in the laboratory tests in the forthcoming studies.

REVIEWER The additional part in the discussion is not understandable without references or connection to the study.

I suggest completing the discussions, with more detailed comparisons with previous studies.

ANSWER The discussion had been integrated accordingly.

 

We attach the revised manuscript

 

Reviewer 3 Report

Comments and Suggestions for Authors

Dear authors, 

thank you for your paper entited Preliminary tests of hybrid cable splice (synthetic-metal) to in- 2 novate timber harvesting in the Mediterranean forestry sector. Chokker workers are maybe the most loaded workers in the forestry sector and every improvement to make easier their work condititions is welcome.

Generally, the paper is well written with all needed information in almost every chapter. Problems in timber extraction in Mediterranean area are well explained, and also the Materials and Methods of the research. Results of the research are clearly described. In Line 281 you have some kind of error. I guess that the link is missing.

In Discussion you explained all very well, but you don`t have any reference to compare your results with other researches, even with only of syntetic ropes. Please try to correct this.

Conclusions are well written.

Kind regards,

Reviewer

 

1. What is the main question addressed by the research?
The main question addresed by the resarch is how to make a durable splicing of the synthetic rope and steel cable with the aim to facilitate work of forest workers using different combinations of hybrid splice of steel and syntetic cables instead of steel cable which is heavy or just a synthetic rope which is lightweight  but not durable and it is very expensive. The research results obtained both the laboratoy testing of the hybrid splice and field tests of different combinations of splicing and comparing the wear of them with the wear of pure synthetic rope.
2. What parts do you consider original or relevant for the field? What specific gap in the field does the paper address?
For the foresty winch extraction field relevant parts are laboratory an field tests of the hybrid splice. In chapter Materials and Methods the procedure of splicing is well described, and also the procedure of research and testing. The paper is relevant because it shows the way how to prolong life and reduce wear of the full synthetic rope.
3. What does it add to the subject area compared with other published material?
Other published material deal mostly with the wear of the fully synthetic rope, not with the combination (splice) of the steel and synthetic rope. Splicing may prolong lifespan of the synthetic rope and still remain the lighgtweight of it.
4. What specific improvements should the authors consider regarding the methodology? What further controls should be considered?
I dont have any remarks concerning methodology. The authors should compare their results with results of other reserchers in Discussion part.
5. Please describe how the conclusions are or are not consistent with the evidence and arguments presented. Please also indicate if all main questions posed were addressed and by which specific experiments.
Conclusions are consistent with the evidence and arguments presented. Authors made conclusions according to the results of the research and according to the problems which were occured during the research.
6. Are the references appropriate?.
The references are appropriate . As I mentioned above, in Discussion part authors should make a comparison of their results with other research results of other authors.
7. Please include any additional comments on the tables and figures and quality of the data.
The quality of figures is good. Results in tables are clearly presented.

 

 

Author Response

REVIEWER Generally, the paper is well written with all needed information in almost every chapter. Problems in timber extraction in Mediterranean area are well explained, and also the Materials and Methods of the research. Results of the research are clearly described. In Line 281 you have some kind of error. I guess that the link is missing.

ANSWER We thank the reviewer for the time dedicated to evaluate our work and the opportunity to improve the manuscript. The error in former line 281 had been corrected.

In Discussion you explained all very well, but you don`t have any reference to compare your results with other researches, even with only of syntetic ropes. Please try to correct this.

ANSWER We agree with the reviewer. A more comparative analysis was needed, even if previous studies had in general a different focus and, most important, not directly comparable data. Yet, we attempted to identify the most similar researches and use them as a comparison for our results.

We attach the revised version of the manuscript.

Reviewer 4 Report

Comments and Suggestions for Authors

Review

The rope (mainly steel) was and is in most countries one of the most common means used for clearing and moving harvested timber, despite the intensive development of timber harvesting using highly mechanized technologies based on the use of harvesters and forwarders. The advantage of using ropes and rope winches is mainly their relative financial simplicity, and above all the universality of their use in various natural and productive conditions of forestry. However, the use of steel ropes by winch skidding is associated with a relatively high physical load and time-consuming manual work when pulling the steel ropes to the wood that should be skidded. Therefore, as the authors also state in the introduction of their article, the possibilities and potential benefits of using synthetic ropes for these purposes have been verified in various ways around the world. However, the results of these verifications were generally characterized by stating that the use of synthetic ropes for skidding is possible and ergonomically beneficial, but it is also handicapped by the significantly reduced service life of synthetic ropes compared to steel ropes. Direct contact of the rope with the surface of the terrain and other obstacles during the skidding leads to relatively rapid damage to the fibers from which synthetic ropes are made. The rope thus wears out and must be replaced soon. This, together with the higher purchase price of synthetic rope, significantly worsens the economic indicators of using synthetic ropes in skidding in the forest. The authors of the presented article present these findings in its introduction and take them as an impetus for the new solution of the "hybrid" steel-synthetic rope, which they dealt with in their studies. From this point of view, the factual content of the article can be considered interesting, and if the applicability of the "hybrid" rope principle for skidding is proven, then we can expect significant impacts of the article on the practical implementation of the new rope principle in forest operational practice, not only in the field of Mediterranean basin in which the research studies were carried out.

The structure of the article and its scope correspond to the usual requirements for works of this kind.

The Abstract of the article presents its factual content in a concise and concise form. Based on it, it is possible to form a good idea about the presented issue, including the carrying capacity of the "hybrid" rope and the amount of wood transported by it during field testing. The keywords of the article provide the basic thematic orientation of the article, but I would recommend adding a keyword on the topic of connecting steel and synthetic rope (hybrid splice), as this is precisely the important subject of this article.

Chapter 1 - Introduction presents the characteristics of forestry in the Mediterranean region in a suitable way, justifies the continued importance of skidding with rope winches in this region and discusses the benefits and problems of using steel and synthetic ropes. The authors properly support their information here with citations of relevant publications by renowned authors. The starting points presented here then lead to the objectives of the research study (thus also the article), which are the construction of a hybrid connection of steel and synthetic rope, its subjection to laboratory tests of load-bearing capacity and, subsequently, practical tests during the skidding by “hybrid” ropes.

Chapter 2 – Materials and Methods introduces the reader to the parameters of the tested steel and synthetic ropes. It is obvious that the authors tested ropes commonly applicable in forestry practice. Subchapter 2.1 describes in detail the method of braiding (joining) steel rope with synthetic. The connection is characterized by the fact that the greater part of the length is made of synthetic rope and only the end part of the rope is made of steel rope. To this steel end a load of wood is tied to the rope, which will then be dragged by it. This is aimed at achieving a longer life of the rope while maintaining the advantage of the low specific weight of the synthetic rope. Methodological procedures for laboratory measurements of "hybrid" ropes and their field tests are described in subsections 2.2 and 2.3. The chapter is compiled clearly and comprehensibly, and in my opinion the described methodological procedures are correct. I have no comments on chapter 2.

Chapter 3 – Results contains an overview of findings obtained by laboratory and field verification of three types of hybrid connections of steel and synthetic ropes. The determined parameters are clearly and comprehensibly arranged in two tables supplemented with brief comments. However, I would recommend that field tests clearly state whether the end of the tests of individual rope variants was caused by fatal damage to a particular rope or whether the end of the tests was determined by the decision of the research team and the tested rope would continue to be usable. Furthermore, I recommend stating the rationale for the possible positive effect of the "hybrid" rope on the productivity of the work when skidding (the conditions in which the field tests were carried out are quite diverse and the interrelationship of the determined performance parameters is therefore not very clear).

Chapter 4 – Discussion comments on the findings presented in the previous chapter. It states, among other things, which method of connecting steel and synthetic rope appears to be more advantageous in terms of the carrying capacity of the "hybrid" rope. If I understand the relevant part of the text (line 321) the authors recommend increasing the length of the steel and synthetic rope tangle. In my opinion, these are relatively essential data, so I would recommend specifying them more clearly in the text and also adding how long the steel parts of the "hybrid" rope should be according to the authors of the article. This is closely related to the practical application of "hybrid" rope in forestry. I have one more comment about this chapter: the authors here "discuss with themselves" (that is, they comment on the findings). However, there are no comparisons with the results of other authors, as there should be in a chapter of this kind. Can it be understood that the research in question is so unique that no thematically similar publications were found? Such a fact does not follow from a number of quotations in chapter 1.

Chapter 5 – Conclusions does not contain a simple summary of the content of the previous parts of the article, as is usually the case, but also presents the future research intentions of the authors in this thematic area. It seems to me that the scope of these visions goes too far beyond the characteristics of the findings presented in the previous parts of the article, and I therefore recommend adjusting their proportions and emphasizing more the important findings presented in the article.

The References part of the article is processed in a standard way, it contains relevant publications by renowned authors, and I have no comments on it.

The submitted article contains interesting and new information. It is built on a scientific basis, uses correct methodological procedures, and its results are applicable in the scientific sphere as well as in the operational practice of forestry (however, other knowledge will probably be added here in the future).

Author Response

REVIEWER I would recommend adding a keyword on the topic of connecting steel and synthetic rope (hybrid splice), as this is precisely the important subject of this article.

ANSWER We than the reviewer for the time dedicated to our manuscript and for the valuable suggestion. We added “hybrid splice” among the keywords.

REVIEWER However, I would recommend that field tests clearly state whether the end of the tests of individual rope variants was caused by fatal damage to a particular rope or whether the end of the tests was determined by the decision of the research team and the tested rope would continue to be usable.

ANSWER This section had been made more clear. According to the planned activity, the crews had a deadline to return the filled daily sheets. This deadline varied depending on the date of delivery of the cable. A minimum of 20 valid filled sheets were posed as a threshold to forest companies for the “gift” of the synthetic cable. Additionally, companies equipped with the hybrid cable were requested to work with it until breakage (if any). In case of breakage, if they were going to continue working with the remaining synthetic cable they were requested to continue filling the report as integration to the companies equipped with pure synthetic since the beginning. Yet, the companies were working according to their commercial schedule, which in some cases brought to interruptions in the use of winch equipped machines. As a result, we have very variable number of days working with the cables provided for the study. Accordingly, the end of the data collection depended on breakage (for hybrid cable, which was not replaced) or end of the recording period for the unbroken hybrid and the pure synthetic cables.  

REVIEWER Furthermore, I recommend stating the rationale for the possible positive effect of the "hybrid" rope on the productivity of the work when skidding (the conditions in which the field tests were carried out are quite diverse and the interrelationship of the determined performance parameters is therefore not very clear).

ANSWER Thanks for the suggestion. We agree that an increase in productivity (and safety) is the ultime goal of the introduction of the hybrid cable in the forestry sector. Yet, in this early stage of development it would have been too ambitious to collect reliable data on durability and productivity altogether. We preferred to focus the efforts to develop a reliable splice and verify the hypothesis of a higher resistance of the hybrid cable compared to pure synthetic. Once the technique will be mature enough, we will estimate its costs (the time required to perform the splice, possibly in the forest). And finally compare it in terms of productivity with the pure synthetic. Yet, the whole idea of the hybrid splice is to have in a unique cable the benefits of steel (higher resistance to abrasion where needed) while keeping a low weight of the overall mass. For this reason, we do not expect to have significant differences in productivity with the hybrid and the purely synthetic cable.

REVIEWER If I understand the relevant part of the text (line 321) the authors recommend increasing the length of the steel and synthetic rope tangle. In my opinion, these are relatively essential data, so I would recommend specifying them more clearly in the text and also adding how long the steel parts of the "hybrid" rope should be according to the authors of the article. This is closely related to the practical application of "hybrid" rope in forestry.

ANSWER Thanks for the suggestion. Indeed, one of the ideas arising from the laboratory tests is that possibly an increased length of the conic steel core may return a more robust hybrid splice. Yet, we did not test it so far as we focused on gathering data and feedbacks also form the use of the hybrid cable in real working conditions. We prioritized this second stage as these tests could have provided data and feedback necessary to get a more comprehensive overview, necessary to guide the next steps of the research. And indeed, we know now that the first priority is to have a hybrid splice with limited diameter increase rather than with longer conic steel core as the first factor hinders completely the use of the hybrid cable. The future research, part of which is already ongoing, will try to address these aspects, but no results are yet available and thus cannot be reported in the present manuscript.   

REVIEWER I have one more comment about this chapter: the authors here "discuss with themselves" (that is, they comment on the findings). However, there are no comparisons with the results of other authors, as there should be in a chapter of this kind. Can it be understood that the research in question is so unique that no thematically similar publications were found? Such a fact does not follow from a number of quotations in chapter 1.

ANSWER Thanks for you comment and analysis. In this case, we disagree. To the best of our knowledge, no similar research had ever been done in the forestry sector. The idea of an hybrid splice was originally conceived in the light naval sector, where work and wear conditions are completely different and thus, not comparable. All quotations in the introduction relate to the advantages or drawbacks of pure steel or synthetic cables in timber hauling. The unique possible relation we found is to the application of chains or chockers as terminals of synthetic cables with a splice eye. This reference (Pilkerton et. al 2003) just suggests this possibility, without a formal study or any data. Yet we integrated it in the new version as an example of a possible solution aiming to solve the same issue.

REVIEWER Chapter 5 – Conclusions does not contain a simple summary of the content of the previous parts of the article, as is usually the case, but also presents the future research intentions of the authors in this thematic area. It seems to me that the scope of these visions goes too far beyond the characteristics of the findings presented in the previous parts of the article, and I therefore recommend adjusting their proportions and emphasizing more the important findings presented in the article.

ANSWER The Conclusions had been revised accordingly.

We attach the revised manuscript. Again, thanks for the valuable suggestions and the opportunity to improve our manuscript.

 

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Thank you for your response and congratulations. 

Comments on the Quality of English Language

Minor editing of English language required