The Importance of Assessing the Level of Service in Confined Infrastructures: Some Considerations of the Old Ottoman Pedestrian Bridge of Mostar
Round 1
Reviewer 1 Report
In this manuscript the social force model, a multi-agent method, is considered in order to simulate the crowd behaviour under different level of service scenarios. The paper is really interested and it is globally well written and organized. Nevertheless, there are several aspect which should be improved in order to be considered for publication in this journal.
Major aspects
According to the reviewer's opinion the authors should include a basic about the social force model in section 3 of the manuscript. At least, a figure and some equations describing the different interaction force and the parameters of Table 6.
Minor aspects
Page 2 Line 55 please it would be recommended to include the original reference about the social force model (] D. Helbing, P. Molnár. Social force model for pedestrian dynamics. Physical Review, 1995, 51 (5), 4282-4286.)
Page 2 Line 66 please it would be recommended to include some additional reference about the use of the social force model to simulate the crowd-structure interaction model in pedestrian bridges (S.P. Carrol, J.S. Owen, M.F.M. Hussein. Modelling crowd-bridge dynamic interaction with a discretely defined crowd. Journal of Sound and Vibration, 2012, 331, 2685-2709.
J.F. Jiménez-Alonso, A. Sáez, E. Caetano, F. Magalhães. Vertical crowd-structure interaction model to analyse the change of the modal properties of a footbridge. Journal of Bridge Engineering ASCE, 2016, 21 (8))
Page 2 Line 89 please the authors should include references for the different models described (discrete selection model, the reticular gas model and the cellular automation model)
Page 2 Line 94 please the authors should include a reference for the social force model (previously mentioned).
Page 3 Line 125 There is a typo in relation to the number of the Table "XX".
Page 3 Line 126 Please the authors should include all the references of Table 1.
Page 5 Line 179 Plese the author should include the reference of the Viswalk software (it has been included later in the manuscript).
Page 11 Line 386 Please the number of the table should be included.
Page 14 Line 458 The "Colour" column is all in white (Table 9).
Author Response
Dear reviewer
we thank you for the valuable advice.
We have included a paragraph on the social force model where we have defined the model and the components of the attractiveness of pedestrians.
As far as the misprints are concerned, we have settled this.
We have included the references you suggested
Reviewer 2 Report
The reviewer has following queries:
1. What do ASocMean and BSocMean exactly represent?
2. In this study, the authors did not explain about data collection clearly.
3. They did not mention about how the parameters are calibrated and Is the calibration done using microscopically or macroscopic data?
4. What is the objective function for the calibration procedure? Did you calibrate using trail and error method?
5. This study just simulated the pedestrian behavior and find out the level of service. The reviewer feel that the study don't have any technical contribution.
Author Response
Dear reviewer, thank you for your valuable contribution
Below we answer your questions:
in lines 379-381 we have defined what ASocMean and BSocMean represent
in lines 424-429 we have better defined the data acquisition method using GoPro type video cameras.
From 405 to 412 the RMSE method used to calibrate the values of the simulator parameters was highlighted.
The study wanted to highlight the criticalities of a confined environment with high pedestrian traffic of tourist type and also provided as a first step of research, some qualitative judgments, in terms of LOS, which can be used as a qualitative judgment by Local Administrations to be able to understand beforehand how much criticality can be correlated to maintenance and evacuation actions of the area.
Furthermore, this parameter may be connected to global indicators characterizing pedestrian bridges by correlating other parameters that are already numerous in the literature with regard to construction materials and maintenance of structures.
Reviewer 3 Report
Keywords, page 1, line 39: Please insert a comma between “Level Of Service” and “Road Safety”
Page 2, line 67: Please change “….because the each walker….” to “….because each walker….”
Page 2, line 89: Please change “….gas model, the cellular….” to “….gas model and the cellular….”
Page 3, line 125: Please change “Table XX” to “Table 1”
Page 3, Table 1: “human”, “qualitative” and “total” must start with a capital letter.
Page 6, Table 3, 4th column: Please change “Ped/m2” to “Ped/m2”
Page 6, Table 4, 2nd and 6th column: Please change “Ped/m2” to “Ped/m2”
Page 7, line 218: Which is the source for the images in Figure 2 ?
Page 8, Table 5, 1st column: Please change the font size for “2nd” so that it will be the same with the rest of the scenario numbering.
Page 11, line 364: Please enter an empty space between “40%” and “female”
Page 12, line 407: Please provide a reference for the value of 0,92m/s
Page 12, line 412: Please enter an empty space between “20-25%” and “.”
Page 14, line 458: “Table 9” must be “Table 8”
Page 14, line 466: The title of Table 9 must appear on page 15
Page 15, Table 9, 1st column: 4th scenario appears as (3rd SCENARIO) and 5th scenario appears as (4th SCENARIO). Please correct them accordingly.
Please cite Reference [4] (page 16) as follows:
Basbas S., Nikiforiadis A., Sarafianou E., Kolonas N. (2019) Behavior and Perceptions of University Students at Pedestrian Crossings. In: Nathanail E., Karakikes I. (eds) Data Analytics: Paving the Way to Sustainable Urban Mobility. CSUM 2018. Advances in Intelligent Systems and Computing, vol 879. Springer, Cham, pp.280-287
Author Response
Dear reviewer
we thank you for the valuable advice.
As far as the misprints are concerned, we have settled this.
We have included the references you suggested
Round 2
Reviewer 1 Report
The authors have responded adequately to the different queries.. The reviewer recomends this paper for publication in this journal.
Author Response
kind reviewer,
we thank you for contributing to the correction of our research work and for recommending the publication in the journal
Reviewer 2 Report
1. The model is microscopically validated using VISWALK? The reviewer
has really doubt about this. Does the VISWALK give trajectory data of
pedestrians?. If yes, how do you extract trajectory in the field. What
type of algorithms did you use for data extraction from the field; any
deep learning or any computer vision techniques. Then, provide images
and videos for trajectory data extraction in the paper.
2. You
mentioned that optimized algorithms are used for calibration. According
to my knowledge VISWALK don't have any optimization techniques. One
option is to write your own code and connect with VISWALK. I hope you
did not perform this. If you have done it, give detail explanation in
the paper.
Author Response
kind reviewer,
we thank you for contributing to the correction of our research work.
We answer your questions below:
considering point 1)
we declare that I used the VIswalk tool (exclusive for weak road users) related to the Vissim software that is specific for microsimulation. The authors declare that through viswalk and its output files it is possible to trace the pedestrian trajectories implemented in the different scenarios studied. In fact, in the article, the vision along the x-axis of the trajectories of three randomly chosen pedestrians has been added as an example and it is also possible to visualize in the figure 3 trajectories can converge or be parallel in some sections along the bridge. The algorithms underlying the viswalk tool are related to the social force model and its evolution. Through shooting with GoPro video cameras and a square mesh evaluation grid and the use of photoshop software on the images it was possible to analyze the real trajectories of pedestrians and thus understand the points of greatest conflict between pedestrians. Through the Viswalk tool, it has been evaluated and compared how the pedestrian can behave with respect to the others in different cases following the model of the social force model on which the tool used is based. In fact, through Viswalk it was possible to analyze the trajectories deriving from the simulation in output and also to analyze the variation in speed and pedestrian density leading to the evaluation of the LOS (Service level) in agreement with the HCM.
It is highlighted that through Viswalk it is possible to study the variation of velocity and density of the areas and derive from the calculation the corresponding LOS value according to HCM.
Instead from the output files generated with different extension,s it is possible to obtain the trajectories of the pedestrians simulated along the x and y axis as the seconds change but also other files that allow for example the surrogate safety evaluation
Some phrases and literature references are completed in red in the article to complete considering this part.
As regards point 2)
the authors declare that they have not written any calculation code.
The comparison between the real value and the simulated one is carried out by definition of Root Mean Square Error (RMSE o RMSD)
Simulated data were obtained from the optimized model and compared with the real field data, in the case of daily normal condition.
In accordance with the literature, an accepted difference in observed and simulated data is less than 10%.
The calibration of the parameters relating to the pedestrian behaviour took place through a sensitivity analysis, ie the effects on the results provided by a model were evaluated (ie the function that describes analytically) induced by changes in the values of the input variables.
Specifically, it was analyzed how the Default set was far from the real behaviour and therefore starting from the evaluation of the videos and from this set of default values, those linked to the others were searched for scenarios, selecting more realistic values both in standard conditions and evacuation or presence of maintenance areas.
Some phrases are completed in red in the article to complete this concept
