Traffic crashes are a social problem around the world and climate change is one of the major environmental factors that cause road crashes. The severity of multi-vehicle crashes under different weather conditions was investigated in this study. Crash data for three levels of crash severity (i.e. crashes involving property damage only (PDO), injury or fatality) from six highways in Iran were evaluated. Ordered logit models were selected for the analysis because of the ordinal nature of crash severity. The final model consists of seven independent variables: temperature below −7°C, temperature above 19°C, rainfall exceeding 5 mm/d, working day of the week, density (vehicles/km), roadside equipment and season of the year. These variables were found to have significant values at 0·95 confidence intervals. The model also showed that the probability of occurrence of a PDO crash is 77·5%, while the probability of occurrence of injury and fatal crashes are 18·9% and 3·6%, respectively.

中文翻译：

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天气对多车相撞严重程度的影响：以伊朗为例

交通事故是世界范围内的社会问题，气候变化是导致道路交通事故的主要环境因素之一。本研究调查了不同天气条件下多车相撞的严重程度。评估了伊朗 6 条高速公路的三个碰撞严重程度级别（即仅涉及财产损失 (PDO)、受伤或死亡的碰撞）的碰撞数据。由于碰撞严重性的序数性质，因此选择了有序 logit 模型进行分析。最终模型由七个自变量组成：温度低于-7°C、温度高于19°C、降雨量超过5 mm/d、一周中的工作日、密度（车辆/km）、路边设备和一年中的季节。发现这些变量在 0·95 置信区间具有显着值。