Application of different negative binomial parameterizations to develop safety performance functions for non-federal aid system roads

Khodadadi, Ali; Tsapakis, Ioannis; Das, Subasish; Lord, Dominique; Li, Yingfeng

doi:10.1016/j.aap.2021.106103

Cited by 18 publications

(9 citation statements)

References 28 publications

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“…The NB-P distribution is the generalized form of the NB model, which is formulated by replacing ϕ with ϕ μ i 2 − p ( 41 , 42 , 48 , 49 ). This results in a mean-variance relationship using the parameter p .…”

Section: Methodsmentioning

confidence: 99%

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Developing Statewide Safety Performance Functions for Commercial Trucks Transporting Hazardous Materials on Interstate Rural Roads in Wyoming

Gaweesh

Ahmed

et al. 2022

Transportation Research Record: Journal of the Transportation R

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Truck crashes in Wyoming are considered a major issue. Nearly 26% of crashes on rural interstate roads involve hazardous materials (HAZMAT) trucks. Wyoming has a high rate of activities related to the energy industry, as it is considered among the top energy producing states in the U.S.A., and mainly relies on the trucking industry for transportation. A crash involving a HAZMAT shipment might have a catastrophic impact because of the nature of the HAZMAT shipment. Therefore, it is crucial to identify the traffic safety performance of HAZMAT trucks, so suitable countermeasures can be identified to reduce the frequency and severity of these crashes. This study aims to develop safety performance functions (SPFs) for crashes involving HAZMAT utilizing traditional negative binomial (NB) models, as well as variations of the NB model, namely, NB-1 and NB-P. The results indicate that HAZMAT truck crashes are associated with vehicle miles traveled, truck percentage, horizontal and vertical characteristics of road geometry, pavement type, and speed limit. The findings from this study show that the NB-P models outperformed the traditional NB models based on likelihood ratio tests, information criteria, and prediction measures. Relevant insights are made on traditional countermeasures, such as road geometry, warning signs, slippery road surface warnings, and climbing lanes, as well as non-traditional countermeasures including updating variable speed limit (VSL) algorithms, adding variable message signs, and integrating roadway geometry information into connected vehicle applications in Wyoming. These could be considered to assist stakeholders and emergency management agencies in better decision making toward safer operations of HAZMAT trucks.

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Section: Methodsmentioning

confidence: 99%

“…The NB-P distribution is the generalized form of the NB model, which is formulated by replacing f with fm i 2Àp (41,42,48,49). This results in a mean-variance relationship using the parameter p. The probability mass function, mean, and variance of the NB-P distribution are given by Greene (49) are provided in Equations 2, 3, and 4:…”

Section: Nb-pmentioning

confidence: 99%

Developing Statewide Safety Performance Functions for Commercial Trucks Transporting Hazardous Materials on Interstate Rural Roads in Wyoming

Gaweesh

Ahmed

et al. 2022

Transportation Research Record: Journal of the Transportation R

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“…Many parametric and non-parametric crash prediction models have been used in the literature. For parametric models, the negative binomial (NB), the Poisson lognormal, the Conway-Maxwell-Poisson, the Poisson-Tweedie, and the Sichel, and, for non-parametric models, deep neural networks and support vector machines are some examples (6)(7)(8)(9)(10)(11)(12)(13).…”

Section: Introductionmentioning

confidence: 99%

Method for Estimating the Monetary Benefit of Improving Annual Average Daily Traffic Accuracy in the Context of Road Safety Network Screening

Zarei

Hellinga

2022

Transportation Research Record: Journal of the Transportation R

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Conventional road safety network screening (NS) relies on measures of historical crash data and annual average daily traffic (AADT) as a measure of exposure to develop safety performance functions. AADT is typically estimated from short-term counts and contains error which can negatively affect NS outcomes and result in the inefficient allocation of safety improvement resources. In this paper, we propose a simulation-based method for quantifying the monetary benefit of improving AADT accuracy. The results of applying the method under various conditions show that crash data sets with higher sample mean and dispersion parameter values are more sensitive to AADT error and consequently benefit more from improving AADT accuracy. The use of the proposed method is illustrated through the application to a real-world example.

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mentioning

confidence: 99%

“…In general, there is extensive literature on the safety and operation of various roadway components using various methods (5)(6)(7)(8)(9)(10)(11). In addition, median openings (12)(13)(14) have been analyzed comprehensively (6)(7)(8). However, very limited studies have specifically considered the operation and safety performance of an unsignalized median opening in the proximity of a signalized intersection (15).…”

mentioning

confidence: 99%

Determining Variables That Influence the Operation and Safety of Median Openings in Close Proximity to Signalized Intersections

Mousavi¹,

Dixon²,

Fitzpatrick³

2022

Transportation Research Record: Journal of the Transportation R

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An effective access management technique can improve both traffic safety and operation along a roadway corridor while maintaining a reasonable level of access to the adjacent properties. Even though raised medians enhance traffic operation and safety by minimizing the number of turning movements at mid-block locations, they shift the potential turning maneuvers to the nearby intersections. Moreover, raised medians have negative economic impacts on the adjacent business owners. Therefore, providing a median opening along a corridor should be evaluated as a trade-off between the gains and losses and installed where the benefits outweigh the potential drawbacks. There is no guideline available that specifically focuses on a median opening in the proximity of a signalized intersection. Therefore, this paper evaluated the safety and operation of the median openings nearby signalized intersections as well as determining the variables that influence the performance of the median openings. The results indicated that the minimum required distance from a median opening to its adjacent signalized intersection is influenced by the number of conflicting driveways, median opening type, and the number of arterial lanes. Moreover, the safety at a median opening is dependent on the median opening type, the number of arterial lanes, and average daily traffic. The results could help transportation agencies to analyze how installing a median opening nearby a signalized intersection affects both traffic safety and operation.

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Application of different negative binomial parameterizations to develop safety performance functions for non-federal aid system roads

Cited by 18 publications

References 28 publications

Developing Statewide Safety Performance Functions for Commercial Trucks Transporting Hazardous Materials on Interstate Rural Roads in Wyoming

Developing Statewide Safety Performance Functions for Commercial Trucks Transporting Hazardous Materials on Interstate Rural Roads in Wyoming

Method for Estimating the Monetary Benefit of Improving Annual Average Daily Traffic Accuracy in the Context of Road Safety Network Screening

Determining Variables That Influence the Operation and Safety of Median Openings in Close Proximity to Signalized Intersections

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