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Investigating the relationship between run-off-the-road crash frequency and traffic flow through different functional
Carlos Roque1, João Lourenço Cardoso1
1Laboratório Nacional de Engenharia Civil, Departamento de Transportes, Núcleo de Planeamento, Tráfego e Segurança, Av do Brasil 101, 1700-066 Lisboa, Portugal.
Accident; Analysis and Prevention
|December 3, 2013
Summary
Highway safety analysis uses crash prediction models. For run-off-road incidents, the relationship between crash frequency and traffic flow is not always increasing, contrary to common assumptions.
Area of Science:
- Traffic safety
- Transportation engineering
- Statistical modeling
Background:
- Crash prediction models are crucial for highway safety analysis.
- These models predict crash frequency and analyze relationships with covariates.
- The functional form of these models is often overlooked in road safety research.
Purpose of the Study:
- To highlight the importance of selecting the appropriate functional form for crash prediction models.
- To investigate the relationship between traffic flow and run-off-road crashes.
- To challenge the assumption of a monotonically increasing relationship between traffic flow and crash frequency.
Main Methods:
- Review of existing literature on crash prediction models in road safety.
- Empirical analysis of run-off-road crash data.
- Consideration of logical factors influencing crash occurrence.
Main Results:
- The functional form of crash prediction models is a critical, yet under-discussed, aspect of road safety.
- For run-off-road crashes, the relationship between expected frequency and traffic flow is not consistently monotonically increasing.
- Evidence suggests a more complex relationship influenced by factors beyond simple traffic volume.
Conclusions:
- The choice of functional form significantly impacts the reliability of crash prediction models.
- A non-monotonous relationship between traffic flow and run-off-road crashes necessitates advanced modeling approaches.
- Future research should focus on developing and validating appropriate functional forms for diverse crash types.
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