Integrated Variable Speed Limits and User Information Strategy

Round 1

Reviewer 1 Report

This work addresses a critical problem to achieving a reduction in the total travel time spent in the network and an increase of the traveled distances, i.e., reducing the overall net-work time despite the increase in assigned flows with extensive verification. The work is valuable to the administrative departments to integrate this technology into traffic control. Thus, it is good to be accepted by addressing some of my comments.

- In the introduction, please provide more information on the speed limits that are adjusted from the methodology perspective.

- Please highlight the contributions of the paper in the introduction explicitly after you describe the problems.

- Please provide a framework diagram at the beginning of section 3. Methodology.

- The figures are blue and not clear. They should be improved. For example, for figures 1-3 figure 7, figure 9, figure 11, and figure 12. The quality is not good. The curves should not only be differentiated by the color but also by the line types.

- It will be interesting if the authors not only mention the macroscopic traffic model but also mention the influence to microscopic traffic. There are many datasets that are used to explore the microscopic traffic behavior given a specific scenario affected by speed limit control. To this end, please at least incorporate some most recent literature: on the assessment of vehicle trajectory data accuracy and application to the next generation simulation (NGSIM) program data; an automated driving systems data acquisition and analytics platform to discuss the influence of using variable speed limit on the microscopic traffic.

- For speed control, with the era of automated and connected automated vehicles or intelligent transportation systems, vehicles can obtain their speed and position information with each other and even the cloud. This information will be useful to apply the variable speed limit control. With that said, please add some discussion by incorporating some speed or position estimation literature to outlook the future work or meaning of this research. Some of the work should be included: autonomous vehicle kinematics and dynamics synthesis for sideslip angle estimation based on consensus kalman filter; automated vehicle sideslip angle estimation considering signal measurement characteristic; vision‐aided intelligent vehicle sideslip angle estimation based on a dynamic model;  improved vehicle localization using on-board sensors and vehicle lateral velocity.

- The conclusions are too lengthy and can be reduced to a concise form. Some suggestions are: move the description language to other parts of the paper; some of the results can be moved to the results and discussion session.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript focuses on the research of variable speed limit control and user information strategy, and their application in actual road network. By using Dynameq simulation software and METANET macromodel to simulate traffic congestion on real highways, and applying variable speed limit control in the control area to evaluate the potential and limitations of the strategy in the actual network, as well as the integration between variable speed limit control and user information strategy. The results show that the integration of the two strategies leads to the redistribution of traffic to a certain extent, which reduces the total travel time and increases the travel distance in the network. Even if the allocated traffic increases, the overall network time can be reduced. It has certain research significance, but there are the following questions worth considering:

1. According to the writing standards of scientific papers, the abstract part should include the background of relevant research, and list the methods, strategies and corresponding conclusions of the research in detail.

 2. The writing of scientific papers has fixed logical order. For example, the introduction part of the article expounds the main contents and methods adopted by the article, but it should be carried out on the basis and shortcomings of previous studies. After that, although the author reviews and analyzes the literature in the research field, it still lacks connection with the research content of this paper.

 3. The author selected and divided the test objects in ' 3.1.1. Test Network ', but readers can not intuitively understand why such settings are needed. When we set constraints, we often take into account various factors, so please explain the scientific basis for such settings.

 4. The clarity of the illustrations in the manuscript is not high, and it is recommended that the author improve the quality of the illustrations. In addition, in order to facilitate readers to read, it is recommended to mark the key nodes in the illustration.

 5. ' Then, the minimum value between that calculated and 90 % of the maximum capacity of the section is selected (... ) ', how to determine the 90 % of the maximum capacity of the section?

 6. In the six illustrations of Fig.3, the author should explain why the six phenomena appear and what the changes from section7 to section12represent.

 7. ' Figure 7. Fundamental diagrams from segment 46 to segment 51. Capacity drop phe-nomenon. ' In the schematic diagram of segment 48, some of the traffic in the simulated state is significantly larger than the capacity of the infrastructure. What is the reason  The author gives an explanation, although this may have little effect on the final result.

 8. In order to facilitate readers to read this paper, it is recommended that the author will draw the main line, branch line in the form of a diagram.

 9. The conclusion of the manuscript does not clarify the main research results, and it is suggested to list the research results in detail.

 10. Check all the details in the manuscript, including the correct format of the caption, as well as the use of reasonable expressions, comprehensive parameter descriptions, etc., and the table should appear where the manuscript first refers to it.

 All in all, the author must sort out the logic of the article according to the writing norms of scientific papers and check all the details of the article. If the author considers continuing to publish the paper in this journal, he should submit it again after checking.

The writing quality of this manuscript is relatively good. This manuscript needs minor editing of English language.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

The paper mainly discusses the benefits of combining VSL with user information system and how this will impact the total travel distance and total time spent.

The title of the paper needs to be revised as it does not concisely reflect the paper topic since it used simulation and studied the user information with the VSL.

The introduction should elaborate about the research problem and the significance of this paper topic supported by previous research.

The state of the art section should have a quick summary at the end to clearly define the research gap.

This section misses some research that have used similar techniques such as

·        "Cell transmission model based variable speed limit control for freeways"

More thorough review of the literature is highly recommended.

Line 37 and 38 should mention which country these highways are from.

Figure 1 shows the results from segment 5 only. What about the rest of the segments

How the used case study for the no control scenario was calibrated?

It would be beneficial to include other measures such as the total delay for each scenario.

Also, it would be beneficial to comment on the environmental impact of using VSL and user information on this macroscopic level.

line 100 a reference is missing

 

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

I was hoping to see the calibration question being addressed in the body of the article.

Author Response

You are right, thank you , we have added in the text of the paper the note and the reference.