Overloading among crash-involved vehicles in China: Identification of factors associated with overloading and crash severity

Objective Evidence suggests that motor vehicle overloading is correlated with the possibility of road crash occurrence and severity. Despite the fact that overloading of motor vehicles is pervasive in developing nations, few empirical analyses have been performed on factors that might influence the occurrence of overloading. The limited studies conducted elsewhere have focused on developed countries where there are differences in infrastructure and economic incentives for overloading. This study aims to address this shortcoming by seeking evidence from several years of crash data from Guangdong province, China. Methods Data on overloading and other factors are extracted for crash-involved vehicles from traffic crash records for 2006-2010 provided by the Traffic Management Bureau in Guangdong province. Logistic regression is applied to identify risk factors for overloading in crash-involved vehicles, and within these crashes to identify factors contributing to greater crash severity. Driver characteristics, vehicle characteristics, road and environmental characteristics, and violation types are considered in the regression models. In addition to the basic logistic models, association analysis is employed to identify the potential interactions among different risk factors during fitting the logistic models of overloading and severity. Results Crash-involved vehicles driven by males from rural households and in an unsafe condition are more likely to be overloaded and to be involved in higher severity overloaded vehicle crashes. While goods vehicles on expressways were more likely to be overloaded compared to other vehicles, this is not the case in mountainous areas. If overloaded vehicles speed, the risk of severe traffic crash casualties increases. In addition, young drivers (aged under 25) in mountainous areas are more likely to be involved in higher severity overloaded vehicle crashes. Conclusions This study identifies several factors associated with overloading in crash-involved vehicles and with higher severity overloading crashes, and provides an important reference for future research on those specific risk factors. These findings also provide support for policymakers developing countermeasures to reduce vehicle overloading.