A Scenario-Based Simulation Model for Earthwork Cost Management Using Unmanned Aerial Vehicle Technology

Round 1

Reviewer 1 Report

This exciting study aimed to design a simulation model that would be able to analyse, manage and monitor costs based on excavation volume. Monte Carlo simulation was used to create the model considering the excavation volume by soil type, which led to various possible results for the excavation cost.

I highlight that the study developed a simulation model that can predict, manage and monitor excavation costs using factors that influence excavation, i.e. excavation volume and cost rates by soil type. The simulation model was validated through application to a case study during the entire life cycle of earthworks, which was the planning, excavation and completion phases.

The above study results highlight the importance of conducting a simulation in which the contractor can periodically check whether or not costs are being managed within the cost range. Using a drone, stakeholders can obtain the actual volume for the simulation.

The simulations and tools used by the authors appear to be valid. The results are detailed with statistical confirmation of the results.

The conclusion is adequate in scope and contains the essential findings of the study. The discussion can be supplemented with additional literature to enrich the authors' arguments.

I evaluate the paper positively because individual simulations were produced that confirmed the authors' claims, and the actual volume and actual costs were recorded in the third phase of the simulation.

When and to what extent do the authors plan to carry out a further study?

Author Response

Thank you for your feedback. Authors have added additional literature to enrich authors’ arguments in the discussion section as stated in Line 400, 451, 457, 463, 465, and 471.

Regarding further study, authors have added more detail explanation in the discussion section Line 455-466. The sentences are “In accordance with Turskis et al. [27] who stated cost risks can be managed through risk monitoring techniques by confirming the magnitude of the risk, the simulation model of this study can assist the subcontractor to take countermeasure actions when there is a possibility of the cost being higher than expected. However, this study is limited by only defining the minimum, average, and maximum value of expected and actual cost. The simulation model can be developed further by setting the cost upper limit or cost contingency, in accordance with Hoseini et al. [28] who said cost contingency must be assigned, calculated, and controlled in construction projects. Cost contingency allows earthwork subcontractor to compensate for the uncertainty of excavation volume [29]. The subcontractor can define the cost upper limit or cost contingency in accordance with subcontractor’s confidence level after considering the risks and the uncertainties.”

Reviewer 2 Report

The manuscript presented by the authors (A Scenario-Based Simulation Model for Earthwork Cost Management Using UAV Technology) proposes a simulation model which can analyze, control, and monitor the cost based on excavation volume using GPS and UAVs. This simulation model intends to reduce /manage risks involved in every aspect of earthwork projects, particularly the cost associated with the volume calculations. In my opinion, the proposed model is interesting and has the potential to be helpful in practice.

The model proposed can be considered under the concept of a “Digital twin (industry 4.0) of the excavation volume”. The digital twin is a “hot” topic in construction and would bring visibility to a future paper. Therefore, I invite authors to bring the digital twin concept to the manuscript, at least as future work. (this is just a suggestion).

 

Despite the quality of the current manuscript, there are some minor corrections/suggestions.

 

Abstract

Ok, but I would like to see some main findings related to applying the simulation model to the case project.

 

Section 3.3. Simulation model concept

Lines 196-197: The sentence “A further development of the simulation model is the optimization and risk management model” needs clarification. Optimization of what? Moreover, the authors must be careful because (usually) the simulation models are not used to optimize but to improve (alternative: find the “best solution”)

 

Section 5. Causal loop diagram

The authors should briefly define the Casual loop diagram (the concept for nonexperts in system dynamics) and explain in a brief sentence how they developed the Casual loop diagram presented in Figure 6. Were there interviews with practitioners, data collection (to develop the model), …? Moreover, I would like to see some discussion on the Casual loop diagram (so readers can understand its rationale)

 

Section 7. Simulation model concept

The authors should briefly define the Stock and flow model (the concept for nonexperts in system dynamics) and explain briefly the rationale of the model developed (Figure 9). Figure 9 should be completed as much as possible with a legend referring to the symbols (rate, stock, …).

 

Section: 8.1. Simulation before excavation (t0-t2 stage)

Lines 374-375: The sentence “The volume of each soil type was conditioned by normal distribution function and standard deviation of 0.1” needs support (either from data or from literature). And 0.1 are in what units?

Lines 381-382: “Simulations were performed 10,000 times to forecast the expected excavation cost, as shown in Figure 11 and summarized in Table 3.” Why 10,000? How did the authors define the number of simulations?

 

Overall, section 8 lacks some discussion of the case study results and the advantages of the proposed model, duly substantiated/compared with the literature (whenever possible).

 

Section 9. Conclusions

 

Ok. 

Author Response

Please see the attached file.

Author Response File: Author Response.pdf

Reviewer 3 Report

The present study develops a simulation model that can forecast, control, and monitor the excavation cost using factors that influence excavation, that is, excavation volume and cost rates per soil type. The simulation model is verified through a case application. The idea is interesting. The overall representation of this paper is technically sound. I have, however, a few comments and suggestions for them.

-The introduction section is inadequate. The introductory section must appropriately highlight the motivations and objectives of this research.

-The authors must refer to more updated articles to improve their paper.

-Please add the organization of the paper in the last part of the Introduction section.

-All the tables and figures are clear, understandable, and relevant, and sources are indicated in each case well. 

-Conclusions are suitable for gaining new results. 

-Must emphasize the rationale and enhancements for future research based on the findings of this study.

 

 

 

Author Response

Please see the attached file.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

I want to congratulate the authors for the improvements in the manuscript.

However, I still have a suggestion about the sentence on lines 399 to 401, which is confusing:

Instead of:

“10,000 samples were used because 10,000 samples are sufficient to get stable results in accordance with Crowder and Moyer [26]. Too few samples generate inaccurate outputs and unbalance histogram plots while too many samples cause a long time to simulate.”

Suggestion:

 

“Samples of 10,000 simulations were considered sufficient to obtain stable results following Crowder and Moyer [26]. Smaller samples would generate inaccurate results and unbalanced histogram plots, while larger samples would take an unnecessarily long time to simulate.”

Author Response

The authors appreciate the reviewer's suggestion.

We have revised the manuscript accordingly.

Please see the revised manuscript.