Fiber-Optical-Sensor-Based Technologies for Future Smart-Road-Based Transportation Infrastructure Applications

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for submitting your review article titled:
“Fiber-Optical Sensor-Based Technologies for Future Smart Road Transportation Infrastructure Applications.”

This manuscript provides a broad overview of fiber-optic sensing technologies applicable to intelligent transportation systems. The authors present several types of fiber-based sensors, their operating principles, and integration possibilities with future smart infrastructure. The topic is timely and relevant, and the article is overall well-structured. However, several areas require revision and enhancement to improve the quality and impact of the manuscript:

1. Literature Update: The manuscript lacks coverage of recent studies (post-2023) in key emerging areas like polymer optical fiber (POF), AI-enhanced distributed sensors, and real-time data fusion systems. Please include relevant recent publications that demonstrate deployment of these sensors in field environments.

2. While many sensor types are listed, the paper would benefit from a clearer comparative analysis of these technologies. Consider adding a summary table comparing cost, resolution, robustness, and maturity (e.g., lab-scale, prototype, deployed).

3. Figures are mostly informative, but the manuscript would benefit from the addition of a conceptual architecture diagram, illustrating the integration of fiber-optic sensors into smart infrastructure. A roadmap figure summarizing technology readiness levels across different sensor types is also suggested.

4. The conclusion should be expanded to include forward-looking perspectives, including:
- Technological challenges (e.g., integration with IoT platforms, power supply constraints, calibration in dynamic environments).
- Potential for data-driven traffic control.
- Opportunities in hybrid sensing (optical + wireless + MEMS).

In summary, the manuscript has merit and addresses a key application area. With revisions aimed at improving depth, clarity, and vision, it could become a strong contribution to the field.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

The manuscript contains multiple minor grammatical errors, such as article misuse, plural-singular agreement, and awkward phrasing. A thorough proofreading by a native speaker or professional editor is strongly recommended to enhance clarity.

Author Response

We thank the reviewer for these valuable suggestions. Please see the response in the .pdf document in the appendix. 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript provides a comprehensive and timely review of Fiber-Optic Sensor (FOS) technologies specifically tailored for smart road infrastructure. The authors successfully bridge the gap between traditional electrical sensing methods and advanced optical solutions. The paper is well-structured, supported by a significant number of references (over 130), and provides clear conceptual frameworks for future integration. While the manuscript is of high quality, the following points should be addressed to enhance its impact:

 

1. While the authors mention that FOS can be fragile during installation, more depth could be added regarding specific "smart" packaging materials that match the modulus of asphalt to prevent "stiffness mismatch," a common issue in road embedding.
2. The manuscript identifies the lack of unified standards as a challenge. A brief discussion on existing protocols (like OPC UA mentioned in Section 4.2) and how they might be adapted specifically for large-scale distributed sensing data would be beneficial.
3. Although FOS systems have higher initial costs due to interrogators, a brief qualitative discussion on "Life-Cycle Cost" (LCC) could strengthen the argument. Reduced maintenance and longer sensor lifespan often offset the initial investment in smart infrastructure.

 

Author Response

We thank the reviewer for these valuable suggestions. Please see the response in the .pdf document in the appendix. 

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors This manuscript presents a review of the most common technologies used for structural monitoring in road infrastructure, encompassing electrical, mechanical, and fiber-optic sensors, as well as related technologies.   In general, the review is well-organized and well-written, and the discussion is also very interesting. I have a few minors to Author as follows: i. In session 1.1, the Authors made a short comparison between resistive strain gauges versus FOS. It would be nice, when possible, to do the same for sessions 1.2 to 1.6; ii. As in the electrical and mechanical sensors description, for the sake of completeness, I would like to suggest that the authors include a session introducing an FBG and highlighting the Bragg condition. Additionally, it would be beneficial to explain to readers the concepts of Brillouin, Raman, and Rayleigh scatterings, including relevant figures and equations.

Author Response

We thank the reviewer for these valuable suggestions. Please see the response in the .pdf document in the appendix. 

Author Response File: Author Response.pdf