Development of Low-Cost Monitoring and Assessment System for Cycle Paths Based on Raspberry Pi Technology

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This study is about developing a low-cost monitoring and assessment system for cycle paths based on raspberry Pi technology. The paper is interesting and of great importance. However, some issues need to be addressed to improve the paper.

1.         The abstract is well presented. However, authors should clearly present the findings of their study.

2.         Authors should consider the research gaps, motivations, and contributions of their study in the introduction section.

3.         Please, present the flowchart of your study as in your methodology, many approaches have been combined.

4.         Please, consider expanding the discussion of your findings in the paper.

5.         Provide a section related to the managerial implications.

6.         Provide the limitations of your study in conclusion, and present more key points related to future studies.

7.         Check the grammatical errors and typos throughout the manuscript and correct them.

Comments on the Quality of English Language

Check the grammatical errors and typo throughout the manuscript and correct them.

Author Response

Manuscript Number: Infrastructures-3435723

Development of a Low-Cost Monitoring and Assessment System for Cycle Paths Based on Raspberry Pi Technology

 

Answer to Reviewers’ Comments

First of all, we thank the Editor and the Reviewers for their valuable comments and suggestions that helped us to improve the quality of our paper.

We revised the manuscript taking into account all the reviewers’ concerns. We report below a detailed description of our changes. Our replies to reviewers’ questions/issues are reported in boldface.

Reviewer #1:

This study is about developing a low-cost monitoring and assessment system for cycle paths based on raspberry Pi technology. The paper is interesting and of great importance. However, some issues need to be addressed to improve the paper.

1. The abstract is well presented. However, authors should clearly present the findings of their study.

Answer 1.1 We thank the reviewer for the valuable suggestion. We have updated the abstract by adding more information about the findings.

Lines 22-28: “[…] as detected using the whole-body vibration a_wz index (ISO 2631 standard). Repeated testing confirmed the system’s reliability by assigning the same vibration comfort class in 74% of cases and an adjacent one in 26%, with an average difference of 0.25 m/s², underscoring its stability and reproducibility. Data post-processing has also focused on integrating user comfort perception, as measured by the whole-body vibration a_wz index (ISO 2631 standard), with image data and it revealed anomaly detections represented by numerical acceleration spikes.”

2. Authors should consider the research gaps, motivations, and contributions of their study in the introduction section.

Answer 1.2  We thank the reviewer for the fruitful comments. We have added the following text in the Introduction section:

Lines 95-102: “Although properly maintained cycle paths play a pivotal role, a research gap per-sists regarding the availability of proactive monitoring solutions through sensing plat-forms specifically adapted to cycling infrastructure. It is important to note that cycling infrastructure differs significantly from conventional road systems and requires specialized, targeted approaches. For conventional roads, parameters such as load-bearing capacity, smoothness, friction, noise, and deep-level deterioration are typically assessed; however, for cycle paths, the fundamental concerns are surface regularity and smoothness to capture relevant surface data.”

Lines 119-126: “The main focus of this study is to propose an affordable, integrated methodology for monitoring and assessing cycle-path conditions addressing the need for a reproducible, data-driven technique. Specifically, this approach contributes to optimizing maintenance, boosting cyclist safety and comfort, and ultimately encouraging the wider adoption of cycling in urban areas. Hence, a novel low-cost system—based on Raspberry Pi technology—has been developed to conduct surface-condition assessments of cycle paths. The prototype integrates an Inertial Measurement Unit (IMU), a Global Navigation Satellite System (GNSS) receiver, a camera, and a magnetic sensor.”

 

3. Please, present the flowchart of your study as in your methodology, many approaches have been combined.

Answer 1.3  Following the reviewer's instruction, we added a flowchart of the study.

Lines 137-139: “Hence, the core contributions of this research is presented in Figure 1.

Figure 1. Flowchart of the proposed methodology.”

4. Please, consider expanding the discussion of your findings in the paper.

Answer 1.4  We express our gratitude to the reviewer for this insightful observation, which provides us with an opportunity to clarify this point.

 

Lines 426-431:  “The proposed system for assessing the condition of cycle paths supports strategic decision-making in road maintenance, complementing existing methodologies and assessment criteria currently applied to road pavement evaluation. The system combines cyclist comfort assessment with visual distress inspection, achieving the objective of improving the management process of this critical infrastructure in support of urban mobility.”

5. Provide a section related to the managerial implications.

Answer 1.5   We express our gratitude to the reviewer for this insightful observation, which provides us with an opportunity to clarify this point.

 

Lines 434-469:

“ 6. Managerial implications

The findings presented in this paper hold significant relevance for municipal authorities, transportation planners, and other stakeholders responsible for the maintenance and enhancement of cycle-path infrastructure. While the previous sections ad-dress the technical issues, the following points outline how the results can support strategic planning and resource allocation in real-world applications:

1. Prioritization of Maintenance Interventions. The low-cost monitoring framework enables more frequent and detailed surveys of cycle-path conditions, including direct measurements of ride comfort via vertical acceleration. By visualizing these data into color-coded maps of problem areas, decision-makers can rapidly identify and rank sections requiring maintenance activities according to the available budget.
2. Shift from Reactive to Proactive Asset Management. Traditional maintenance strategies often rely on sporadic visual inspections. The proposed integrated system could support early detection. Implementing regular surveys can reduce long-term repair costs and lower safety risks by addressing emerging issues before they escalate.
3. Enhanced Transparency and Stakeholder Engagement. Quantitative data on vibration levels, combined with camera-based snapshots of road conditions, allow municipal managers to communicate infrastructure needs to governing bodies and the public in a clear, evidence-based manner. This approach fosters transparency and can strengthen public trust and support for budgeting decisions or policy initiatives aimed at expanding and maintaining safe cycling facilities.
4. Support for Sustainable Urban Mobility Goals. Many cities aspire to increase the bicycle usage in order to reduce traffic congestion, greenhouse gas emissions, and noise pollution. By objectively measuring user comfort and safety, transportation agencies can identify precise barriers that discourage cycling and devise targeted interventions to address them. This data-driven methodology aligns with broader sustainability targets and the pursuit of more inclusive urban environments.
5. Scalability and Integration into Broader Smart-City Strategies. The monitoring system leverages open-source hardware and software, enabling cost-effective deployment at a larger scale or in multiple municipalities. As cycle-path networks continue to expand, the same framework can be replicated to create a more com-prehensive overview of cycle path conditions.

By embracing proactive, data-guided monitoring practices, local authorities and other relevant organizations can increase the overall resilience, safety and functionality of cycling infrastructure. Such practices directly contribute to encouraging a shift toward greener, safer, and more efficient modes of urban transport.”

6. Provide the limitations of your study in conclusion, and present more key points related to future studies.

Answer 1.6  We agree with this point and have substantially revised the conclusion section by providing the limitations of our study and present future studies.

Lines 495-503: “Nonetheless, certain limitations should be noted. All field tests were performed using a single e-bike configuration, which may not capture variations introduced by different bicycle types or suspension systems. Additionally, data were collected under moderate urban traffic and weather conditions; more complex scenarios, such as heavy congestion or extreme climates, could affect sensor accuracy. The approach also focuses primarily on objective ISO 2631 measurements without direct user feedback, a factor that might refine comfort thresholds when combined with subjective reports. Finally, despite including cobblestone and asphalt surfaces, other potential pavement types (e.g., eco-friendly materials) remain outside the scope of this study.”

Lines 507-512: “Future studies could explore additional bicycle configurations and more demanding environmental contexts, integrate cyclist feedback or biometric sensors for a deeper correlation with perceived comfort, and test the system on further surface types to ensure broader applicability. Future research could also focus on refining the comfort classification model and extending the system's application to diverse urban environments.”

7. Check the grammatical errors and typos throughout the manuscript and correct them.

Answer 1.7  We thank the reviewer for the valuable suggestion, and we revised the manuscript correcting the grammatical errors and typos.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

1. In actual cycling, there is a lack of subjective experience feedback from users.
2. Testing with only one type of bicycle cannot reflect the cycling experience of various types of bicycles.
3. The article does not mention the adaptability of sensor accuracy in complex traffic conditions and other environments.
4. The specific classification of bicycle comfort is not explained.
5. The specific calculation method and source of the frequency weighting $W^{k,i}$ are not described in detail.
6. More effective multi-source data can be integrated into the GIS to enhance the potential of the system in practical applications.
7. There is no detailed comparison with other similar cycling path monitoring systems.
8. The types of sidewalks mentioned in the article are not comprehensive enough.

Author Response

Manuscript Number: Infrastructures-3435723

Development of a Low-Cost Monitoring and Assessment System for Cycle Paths Based on Raspberry Pi Technology

 

Answer to Reviewers’ Comments

First of all, we thank the Editor and the Reviewers for their valuable comments and suggestions that helped us to improve the quality of our paper.

We revised the manuscript taking into account all the reviewers’ concerns. We report below a detailed description of our changes. Our replies to reviewers’ questions/issues are reported in boldface.

 

Reviewer #2:

1. In actual cycling, there is a lack of subjective experience feedback from users.

Answer 2.1: The methodology presented in this study focuses primarily on objective, sensor-based measurements (e.g., accelerations, GPS data, and camera footage). These metrics enable an efficient, reproducible means of detecting pavement irregularities and calculating comfort levels (via ISO 2631). However, it is recognized that subjective feedback—such as riders’ perceptions, comfort ratings, or physiological responses—would provide further insight into how different surfaces or anomalies affect real-life cycling experiences.

 

In the scope of this project, gathering subjective user feedback lay beyond the primary objectives, which involved developing and validating a low-cost, technology-driven approach for cycle-path condition assessment. Nevertheless, future research might integrate direct user-reported data (e.g., mobile app surveys, wearable biometric sensors, or in-person interviews) alongside the objective, sensor-derived indicators of pavement quality. We added the following text in the Conclusions

Lines 499-501: “ The approach also focuses primarily on objective ISO 2631 measurements without direct user feedback, which could refine comfort thresholds when combined with subjective reports”

Lines 507-512: “Future studies could explore additional bicycle configurations and more demanding environmental contexts, integrate cyclist feedback or biometric sensors for a deeper correlation with perceived comfort, and test the system on further surface types to ensure broader applicability. Future research could also focus on refining the comfort classification model and extending the system's application to diverse urban environments.”

2. Testing with only one type of bicycle cannot reflect the cycling experience of various types of bicycles.

Answer 2.2: The study focused on demonstrating a low-cost, sensor-based methodology rather than capturing the full spectrum of bicycle variations. While the e-bike platform employed served as a consistent, repeatable test bed for data collection, it is acknowledged that other bicycle types (e.g., mountain bikes, road bikes, or hybrids) with different suspension, frame geometry, and tire properties could produce different vibration responses. The current approach nonetheless provides a foundational framework that can be adapted or extended. As indicated in our manuscript’s ‘Conclusions’ section, future work will include testing multiple bicycle configurations to assess how these structural differences influence the ISO 2631–based comfort evaluations and to further validate the generalizability of the proposed system

Lines 495-497: “Nonetheless, certain limitations should be noted. All field tests were performed using a single e-bike configuration, which may not capture variations introduced by different bicycle types or suspension systems”

Lines 507-511: “Future studies could explore additional bicycle configurations and more demanding environmental contexts, integrate cyclist feedback or biometric sensors for a deeper correlation with perceived comfort, and test the system on further surface types to ensure broader applicability.”

3. The article does not mention the adaptability of sensor accuracy in complex traffic conditions and other environments.

Answer 2.3: The current investigation focused on validating the sensor platform under typical urban cycling environments with moderate traffic volumes. Within this scope, the system proved robust, as the GPS snapping technique and IMU-based vibration detection performed reliably. However, the manuscript does acknowledge that heavier traffic, extreme weather, or off-road scenarios might influence signal accuracy and introduce additional noise factors. We plan to extend the methodology to include more variable traffic flows and environmental extremes in future trials, thereby verifying the adaptability of the sensor suite under more complex conditions. This staged approach allows thorough proof-of-concept validation before undertaking the complexities inherent in highly congested or specialized environments.

Lines 497-499: “Additionally, data were collected under moderate urban traffic and weather condi-ions; more complex scenarios, such as heavy congestion or extreme climates, could affect sensor accuracy.”

Lines 507-511: “Future studies could explore additional bicycle configurations and more demanding environmental contexts, integrate cyclist feedback or biometric sensors for a deeper correlation with perceived comfort, and test the system on further surface types to ensure broader applicability.”

 

4. The specific classification of bicycle comfort is not explained.

Answer 2.4: The comfort classification employed in our study is grounded in the ISO 2631 framework for whole-body vibration, which provides a robust methodology for interpreting weighted accelerations. Specifically, we defined four comfort classes (Table 4) by setting threshold values (0.80, 1.20, and 1.80 m/s2) that align with ranges cited in prior vibration studies for bicycle and vehicle applications [32,36]. Because the IMU was attached to the saddle, the thresholds were modestly adjusted to compensate for reduced accelerations compared to human-body measurements. This approach ensures that the vibration indices reported more closely match the actual cycling experience, even though precise calibration across different rider postures or suspension setups may vary.

5. The specific calculation method and source of the frequency weighting Wk,i are not described in detail.

Answer 2.5: The manuscript references the ISO 2631 standard [24]: we felt it sufficient to cite ISO 2631 rather than reproduce the entire calculation method in detail. In the same way, frequency-weighting Wk,i are reported in its guidelines for whole-body vibration and in our approach we directly apply these standardized coefficients without additional customization.

6. More effective multi-source data can be integrated into the GIS to enhance the potential of the system in practical applications.

Answer 2.6: The current system successfully integrates sensor-derived accelerations, GPS coordinates, and camera frames into a GIS platform, enabling a robust georeferenced analysis of cycle-path conditions. It is acknowledged that the inclusion of additional data streams—such as crowdsourced user feedback, real-time weather information, or traffic flow data—could further enrich the predictive power and applicability of the tool. While the present paper focuses on demonstrating the feasibility of low-cost hardware and a repeatable methodology, future research will consider these broader data sources to provide a more comprehensive decision-support framework for urban infrastructure management.

7. There is no detailed comparison with other similar cycling path monitoring systems.

Answer 2.7:

The study employed a single e-bike configuration to maintain a controlled test environment and demonstrate the reliability of the proposed methodology. This allowed for clear, reproducible comparisons of pavement-induced vibrations without introducing extraneous variables, ensuring robust validation of the core sensor framework. While we acknowledge that different bicycles may exhibit variations in recorded accelerations, the proof-of-concept is nevertheless valid and sufficient as a scientific article, as it confirms the system’s ability to detect and map pavement anomalies in a repeatable manner. Future work may include testing with additional bicycle types to broaden the applicability of the findings, but this does not diminish the present study’s relevance or completeness.

 

Lines 325-329: “The study employed a single e-bike configuration to maintain a controlled test environment and demonstrate the reliability of the proposed methodology. This approach enabled for clear and reproducible comparisons of pavement-induced vibrations without introducing extraneous variables, ensuring the robust validation of the core sensor framework.”

8. The types of sidewalks mentioned in the article are not comprehensive enough.

Answer 2.8: The article explicitly focuses on cobblestone, asphalt found in Rome’s cycle paths, as these were deemed representative of the typical urban environment we sought to analyze. We acknowledge, however, that many other sidewalk and pathway materials exist (e.g., concrete blocks, rubberized surfaces). The method is not limited to these surfaces alone; in future expansions, testing additional pavement materials can provide a more exhaustive assessment of the system’s adaptability. As stated in the revised manuscript text, the overall approach—accelerometric and camera-based evaluation—can be applied to any paved surface once baseline ride characteristics and sensor calibration are established.

Lines 317-325: “This study examined on a selection of cycle paths and sidewalks whose pavement sur-faces—namely cobblestones and asphalt—represent typical urban cycle pavements in Rome. While these materials represent a useful range of both smooth and discontinuous pavements, they do not encompass all possible sidewalk or cycle-path surfaces (e.g., concrete tiles, permeable pavers, rubberized segments). However, the proposed methodology remains adaptable to other pavement types, as the core sensor-driven approach (i.e., weighted vertical acceleration measurement and image-based verification) can be applied wherever a consistent path surface needs monitoring.”.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The paper has been revised accordingly and the authors have responded to all my comments. Thereby. I recommend the paper to be accepted as is.