Impacts of Real-Time Traffic State on Urban Expressway Crashes by Collision and Vehicle Type
Round 1
Reviewer 1 Report
The authors have worked on a very important theme of crash modelling. Overall, the outcomes are important. The following points may be added for better clarity.
- Why the roadway factors are not considered in modeling ?
- The statistical information on the number of data points may be added.
- Why Negative Binomial should be refereed more.
- How random effect is brought in the modelling is not clear.
- The constant value is negative and higher except for heavy vehicle proportion. I think the authors may identify other variables particularly on driver's behaviour.
- The practical examples of study should be given towards the end of the manuscript.
- Overall, some policy interventions should be suggested.
- Why risk and severity by crash type is not considered?
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
The authors introduced a random effect negative binomial model to study the relationship between traffic flow parameters and crash frequency on the urban expressways. The results are novel and the paper is well writing
Author Response
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Author Response File: 
Author Response.docx
Reviewer 3 Report
The authors should define more clearly in the introduction section which are the contributions of this paper compared to many other similar analyses, as they've actually detailed in the introduction.
Moreover, to me, it seems very curious that from 1188 crashes in the crash data, 353 crashes involved only heavy-duty vehicles and 835 crashes involved only light-weight vehicles, which sums up to 1188. There are no crashes that involved both types of vehicles? And from this hypothesis all the conclusions would reflect another view.
Furthermore, please revise the English form throughout the paper, because there are many typos encountered.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors have incorporated my suggestions satisfactorily.
Reviewer 3 Report
The authors have answered to all the questions raised by the reviewers.
