UNC Charlotte Autonomous Shuttle Pilot Study: An Assessment of Operational Performance, Reliability, and Challenges

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript presents a comprehensive study of a Level 4 autonomous shuttle pilot program, detailing the completion of 825 trips and the transportation of 565 passengers along a 2.2-mile mixed-traffic campus route. Through autonomy disengagement data collection and operational efficiency data collection, the study conducts evaluation tests on service robustness, service reliability, service usage, and service performance. Overall, the work is thorough and provides valuable insights into the pilot program.

However, several key issues need to be addressed to enhance the clarity and contribution of the research:

1. Insufficient System Explanation: While the paper mentions the use of LiDAR sensors, cameras, GPS, and IMU sensors, it does not provide a detailed explanation of the system's working principles and processes. This omission may hinder the reader's ability to fully grasp the operational mechanisms.

2. Absence of Algorithmic Details: The paper does not discuss the navigation algorithms, path planning, or obstacle avoidance methodologies used in the system. This lack of detail considerably limits the research's value for scholars in terms of theoretical methodologies and technical applications.

Author Response

 Thank you for your thorough review and constructive suggestions. While the detailed workings of specific algorithms, such as path planning and obstacle avoidance, are not the primary focus of this paper, we acknowledge the importance of this context. Our paper is focused on focuses on evaluating the technological performance of the automated shuttle, with an emphasis on assessing its operational efficacy and identifying key challenges. However, we have added relevant references to support readers interested in exploring these algorithmic aspects further.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Overall, the article is well-written and easily comprehensible, particularly in the introduction and literature review sections. The topic addressed is timely and highly relevant. I think it would be better if the units were placed in the metric system (International System).  I found typos that will have to be corrected for the final version of the manuscript. For my part, once these corrections have been made, the article can proceed to publication.

Line 32: Add a reference.

Line 282: “The data indicates that the shuttle successfully transported 565 riders on 825 individual trips”

·        How many rides were made without any passengers?

Line 358: Table 8 should be Table 2.

Line 435: Table 1 should be Table 4.

Line 511: Table 10 should be Table 5.

Line 524: 11:30 AM

Line 527: Figure 11 should be Figure 14.

Author Response

We appreciate your attention to detail and the specific corrections suggested. We have made the following changes:

• References and Corrections:
  • Line 32: A reference has been added to support this statement.
  • Line 282: We clarified that 62 trips had no passengers and updated the manuscript accordingly.
  • Table and Figure Numbering: The suggested corrections for tables and figures (e.g., changing Table 8 to Table 2, Table 1 to Table 4, Figure 11 to Figure 14) have been implemented to ensure consistency.
  • Formatting Corrections: Other adjustments, such as using the correct time format "11:30 AM," have been applied.

Thank you for your careful attention to detail, which has improved the precision of our presentation.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

My comments are attached.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

They are included in the above attached document.

Author Response

Thank you for your valuable suggestions, which have significantly contributed to improving the organization and readability of our manuscript. The following changes have been made:

• Keywords: The keywords have been reordered alphabetically, and we have included "vehicle-to-infrastructure communication" as recommended.

• Figure and Table Adjustments:

  • Figure Captions and Placement: We removed extraneous details from figure captions (e.g., Figure 3) and integrated the explanatory information within the main text. Figures have been repositioned as suggested, including relocating Figure 4 to enhance the document's flow.
  • Formatting Improvements: Consistent punctuation has been applied to titles and captions across all tables and figures, with captions positioned according to your recommendations.

• Content Corrections and Enhancements:

  • Battery Efficiency Explanation: We refined the discussion on battery efficiency to highlight the impact of cooling systems in hot weather.
  • Typographical Corrections: Minor typographical errors, such as the caption for Figure 1, have been corrected.
  • Lines 644-649: We appreciate your observation on these lines, which were referenced in error. This reference has been removed.

Thank you again for your invaluable feedback, which has greatly enhanced the clarity and professionalism of our manuscript.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The autonomous shuttle is a very complex project. It's true that this paper focused on the experiments and assessments of the auto pilot program. There should be a brief introduction of the localization and navigation principle, the path planning method of the system. And the method mentioned in the reference paper is also too general.