Comparative Analysis of Child Restraint Systems Safety Parameters in Relation to the New Regulation No. 129 of the Economic Commission for Europe of the United Nations (UN/ECE)
Round 1
Reviewer 1 Report
Although this research is outside my primary discipline, I very much enjoyed reading the paper. It is well-structured, well-written and very clear. However, I have some comments that may improve the quality of the papers. Some comments may be unusual for this discipline; in that case, please ignore.
Would it be possible to show pictures of the different devices in the Appendix? It would increase the readability if all figures had more extensive notes and could stand alone. I would omit the second (and potentially first) digit after the decimal in the figures. Instead, note that US readers are used to "." not "." More importantly, however, isn't each device tested several times? Have I overlooked the number of tests for each device? If tests have been carried out more than once, in my discipline we would plot the bar diagrams along with statistical confidence intervals. (Adding confidence intervals to the figures is my single most important comment.) I would put most language into active voice and try to avoid passive voice. Some of the figures look a bit blurry. The references are not consistently formatted (sometimes title capitalized, sometimes not).
Author Response
Dear Reviewer,
We would like to thank you for your revision and valuable comments.
In connection with your suggestion we have made the following corrections:
- “Would it be possible to show pictures of the different devices in the Appendix?”
We put the pictures taken during tests in the appendix in Table 1 as a part of the experiment description.
- “It would increase the readability if all figures had more extensive notes and could stand alone. “
We made more extensive notes and put the pictures to the end of the article as an appendix. Additional text was yellow-highlighted.
- “I would omit the second (and potentially first) digit after the decimal in the figures. Instead, note that US readers are used to "." not "." “
We rounded the figures out to the first digit after the decimal and changed “,” to “.”.
- “More importantly, however, isn't each device tested several times? Have I overlooked the number of tests for each device? If tests have been carried out more than once, in my discipline we would plot the bar diagrams along with statistical confidence intervals. (Adding confidence intervals to the figures is my single most important comment.)”
All tested Child Restraint Systems have been approved according to ECE Regulation No. 44. It means that the manufacturer must meet strict conditions regarding the repeatability of the results of all manufactured devices. The holder of approval shall be obliged to carry out continuous quality control of his manufacturing process on a statistical basis and by sampling. In agreement with the relevant authorities, the tests can be carried out by the Technical Service authorities or under the responsibility of the holder of approval which is responsible for the traceability of the product. Control shall meet the following requirements:
- in normal mode 0.2 percent means one child restraint system taken from every 5 000 manufactured;
- in strengthened mode, 0.05 percent means one child restraint system taken from every 2 000 manufactured.
Where a test sample fails a particular test to which it has been subjected, a further test to the same requirement shall be carried out on at least three other samples. It is very important that in the case of dynamic tests, if one of the latter fails, the production is considered to be non-conforming and the frequency shall be raised to the higher one if the lower one was used and necessary steps shall be taken to re-establish the conformity of the production. When production is found to be non-conforming, the holder of the approval or his duly accredited representative shall notify the Type Approval Authority which has granted type approval indicating what steps have been taken to re-establish the conformity of production. The manufacturer must advise the Type Approval Authority on a quarterly basis, the volume of products produced against each approval number, providing a means of identifying which products correspond to that approval number.
We would like to admit that all tests were carried out in an accredited laboratory according to the approval procedure contained in the new Regulations No. 129. In addition, the tests were carried out on repetitive samples that have been approved according to Regulation No. 44.
- “I would put most language into active voice and try to avoid passive voice”
We did our best to improve the language into a more active voice.
- “Some of the figures look a bit blurry.”
We fixed it.
- “The references are not consistently formatted (sometimes title capitalized, sometimes not).”
The references have been formatted regarding your comment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
the work is partially structured.
It is necessary to insert more details in the abstract and in the conclusions to better understand the subject matter and the evaluation method adopted.
There are numerous typos and misspellings.
A greater description is required before and after each graph, highlighting what has been obtained.
In various graphs, the units of measurement of the x and y axes are missing
Author Response
Revision #2
Dear Reviewer,
We would like to thank you for your revision and valuable comments.
In connection with your suggestion we have made the following corrections:
- “The work is partially structured.”
We fixed the structure of the work by adding more information from other paragraphs. Added parts were yellow-highlighted.
- “It is necessary to insert more details in the abstract and in the conclusions to better understand the subject matter and the evaluation method adopted.”
We put more details in the abstract and yellow-highlighted it:
Almost all selected CRS met requirements pointed in Regulation No. 129. The only exception was for abdominal pressure in one of the tested devices. One of the most important parameters measured during crash tests is HIC (Head Injury Criterion). Head Resultant Acceleration in tested devices was 14.7 – 39.0% less than a limit determined in Regulation No. 129 whereas Chest Resultant Acceleration was 17.4 – 37.6% less. Abdominal pressure was 46.4% - 81.4% beneath the limit (apart from one case which didn’t meet the requirements). HPC parameter (Head Performance Criterion) was 45.4 – 74.5 % less.
And in the conclusions:
As an example where the parameters significantly differ may be a Right Abdominal Pressure – the differences range between each CRS are 7% (Concord Transformer X – Britax Romer Kid II) even to 70% (Combi Booster Seat – Combi Joy Trip Egg Shock).
The conclusion is there is no any perfectly restraining device because of its design – each CRS is built differently what causes different protection range of determined sensitive point on child’s body, for example, Smart Kid Belt is marked by highest results in safety parameters such as HPC - 25.5% and HIC - 61% but it does not provide as good protection as other CRSs of right and left abdominal– 57.6% and 38.9% (the worst one of all others). The best protection of abdominal provides Combi Booster Seat – 18.6% (left side) which means 81.4% beneath the limit and 33.1% (right side).
All tested Child Restraint Systems have been approved according to ECE Regulation No. 44. which means that the manufacturer has to meet strict conditions regarding the repeatability of the results of all manufactured devices. The holder of approval shall be obliged to carry out continuous quality control of his manufacturing process on a statistical basis and by sampling. Control shall meet the following requirements:
- in normal mode 0.02 percent means one Child Restraint System taken from every 5 000 manufactured;
- in strengthened mode, 0.05 percent means one CRS taken from every 2 000 manufactured.
Where a test sample fails a particular test to which it has been subjected, a further test to the same requirement shall be carried out on at least three other samples. In the case of dynamic tests, if one of the latter fails, the production is considered to be non-conforming and the frequency shall be raised to the higher one if the lower one was used and necessary steps shall be taken to re-establish the conformity of the production.
- “There are numerous typos and misspellings.”
We rephrased some numerous typos and misspellings.
- “A greater description is required before and after each graph, highlighting what has been obtained.”
We added the following amendments and yellow highlighted it:
The first chart shows Chest Resultant Acceleration which means how does the acceleration change in time. It allows to compare how particular device works – delay of initiation of action, that is why each peak is displaced from the other. There are two accumulations of peaks, the first one is considered because of the impact occurs - rapid deceleration of the test bench. There are the highest peaks that give information about accelerations in the child's body.
The biggest acceleration was in Combi Booster Seat and Combi Joy Trip Egg Schock what may be caused by connecting the CRS to a vehicle by adult seat belt which does not provide enough restraining strength on a child’s body.
The comparison of the limit of acceleration pointed in Regulation No. 129 was made with obtained actual results of the test. Final results are shown in the bar chart below – it is a ratio between test results and Chest Resultant Acceleration specified in the Regulation (55 g), which determines in a percentage way safety parameters of particular Child Restraint System.
- “In various graphs, the units of measurement of the x and y axes are missing”
We have added missing units.
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
the work is now better structured although there are still typos and grammatical errors
