Urban Arterial Accident Prediction Models with Spatial Effects

Author(s):  
Karim El-Basyouny ◽  
Tarek Sayed
2009 ◽  
Vol 41 (5) ◽  
pp. 1118-1123 ◽  
Author(s):  
Karim El-Basyouny ◽  
Tarek Sayed

Author(s):  
Bhagwant Persaud ◽  
Dominique Lord ◽  
Joseph Palmisano

Accident prediction models, also known as safety performance functions, have several important uses in modern-day safety analysis. Unfortunately, calibration of these models is not straightforward. A research effort was undertaken that demonstrates the complexity of calibrating these models for urban intersections. These complexities relate to the specification of the functional form, the accommodation of the peculiarities of accident data, and the transferability of models to other jurisdictions. Toronto data were used to estimate models for three- and four-legged signalized and unsignalized intersections. Then the performance of these models was compared with that of models for Vancouver and California that were recalibrated for Toronto using a procedure recently proposed for the application in the Interactive Highway Safety Design Model (IHSDM). The results of this transferability test are mixed, suggesting that a single calibration factor as is currently specified in the IHSDM procedure may be inappropriate and that a disaggregation by traffic volume might be preferable.


2006 ◽  
Vol 33 (9) ◽  
pp. 1115-1124 ◽  
Author(s):  
Z Sawalha ◽  
T Sayed

Accident prediction models are invaluable tools that have many applications in road safety analysis. However, there are certain statistical issues related to accident modeling that either deserve further attention or have not been dealt with adequately in the road safety literature. This paper discusses and illustrates how to deal with two statistical issues related to modeling accidents using Poisson and negative binomial regression. The first issue is that of model building or deciding which explanatory variables to include in an accident prediction model. The study differentiates between applications for which it is advisable to avoid model over-fitting and other applications for which it is desirable to fit the model to the data as closely as possible. It then suggests procedures for developing parsimonious models, i.e., models that are not over-fitted, and best-fit models. The second issue discussed in the paper is that of outlier analysis. The study suggests a procedure for the identification and exclusion of extremely influential outliers from the development of Poisson and negative binomial regression models. The procedures suggested for model building and conducting outlier analysis are more straightforward to apply in the case of Poisson regression models because of an added complexity presented by the shape parameter of the negative binomial distribution. The paper, therefore, presents flowcharts detailing the application of the procedures when modeling is carried out using negative binomial regression. The described procedures are then applied in the development of negative binomial accident prediction models for the urban arterials of the cities of Vancouver and Richmond located in the province of British Columbia, Canada. Key words: accident prediction models, overfitting, parsimony, outlier analysis, Poisson regression, negative binomial regression.


2008 ◽  
Vol 35 (6) ◽  
pp. 647-651 ◽  
Author(s):  
Eric Hildebrand ◽  
Karen Robichaud ◽  
Hong Ye

This paper evaluates the accuracy of three commonly used models that predict accidents on two-lane, rural, arterial highways. The retrospective evaluation compared model outputs with empirical collision results for a sample of highway sections in the Province of New Brunswick. The analysis determined historical accident rates, identified key predictive variables, and compared the observed results with estimates from each safety model. All three models were found to significantly overestimate accident frequencies on the highway sections under study. The model generally employed in New Brunswick, MicroBENCOST, was found to yield the highest errors in estimated collisions. These findings suggest that the benefits from accident reduction are generally overestimated on highway improvement projects analyzed with these accident prediction models.


1996 ◽  
Vol 28 (6) ◽  
pp. 695-707 ◽  
Author(s):  
Linda Mountain ◽  
Bachir Fawaz ◽  
David Jarrett

Author(s):  
Ahmed Osama ◽  
Tarek Sayed

With the increasing demand for sustainability, the use of cycling as an efficient active mode of transportation is being encouraged. However, the vulnerability of cyclists to severe injuries in crashes can discourage road users from cycling. Therefore, the study of the factors that affect the safety of cyclists is important. This paper describes an investigation of the relationship between cyclist–motorist crashes and various traffic zone characteristics in Vancouver, British Columbia, Canada. The goal was to assess the impacts of socioeconomics, land use, the built environment, and the road facility on cyclist safety through the use of macrolevel collision prediction models. The models were developed by generalized linear regression and full Bayesian techniques. An actual bike exposure indicator (the number of bike kilometers traveled) and the number of vehicle kilometers traveled were used as exposure variables in the models. The safety models showed that cyclist–motorist crashes were nonlinearly associated with an increase in bike, vehicle, and transit traffic as well as socioeconomic variables (i.e., population, employment, and household densities), variables related to the built environment (transit stop, traffic signal, and light pole densities), commercial area density, and the proportion if arterial–collector roads. The models revealed, however, a decline in cyclist–motorist crashes in association with an increase in the proportions of local roads and off-street bike links and an increase in recreational and residential area densities. The spatial effects were accounted for in the full Bayes models and were found to be significant; such a finding implies the importance of consideration of the spatial correlation in the development of macrolevel cyclist safety models.


2014 ◽  
Vol 1065-1069 ◽  
pp. 3372-3376
Author(s):  
E Lu ◽  
Jing Liang Xu

At home and abroad research, accident rate prediction model for highway safety assessment contains various influence factors, so it is difficult to find a comprehensive accident prediction model considering so much of them. In this article, we select appropriate accident prediction models through comprehensive literature research respectively about the highway alignment conditions, traffic conditions, interchange spacing conditions, then determine the weights of three accident prediction models using the analytic hierarchy process (AHP), finally obtain the comprehensive safety assessment model after the consistency check. Its’ feasibility is proved by a practical example.


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