Factors related to highway crash severity in Brazil through a multinomial logistic regression model

Reducing the number of deaths by road crashes is an important priority for many countries around the world. Although focusing on the occurrence of crashes can provide safety policies that help reduce its numbers, studying their severity can provide different measures that may help further reduce the number of deaths by focusing on the most severe problems first. In this paper, a multinomial logistic regression model is fitted to nationwide highway crash data in Brazil from 2017 to 2019 to identify and estimate the associated factors to crash severity. Severity is classified as without injury, with injured victims or with fatal victims. Amongst other observations, results indicate that pedestrian involvement in highway crashes increase dramatically their severity. Also, conditions that favor greater speeds (clear weather, times when there are fewer vehicles on the road) are also related to an increase in crash severity, pointing to a proportional relation with traffic fluidity. Moreover, some observed limitations on the data may indicate that Brazil would benefit greatly from national crash records standards and unified databases, especially crossmatching crash reports with health data.