Abstract: Small climate on freeway has a certain relationship with the number of traffic accidents on it.By use of the measured data of 4 automatic weather stations of Jishou-Fenghuang，Jishou-Chadong freeway (referred to as Ji-Feng-Cha freeway) in 18 months，the weather information observed by highway policemen from April 2012 to June 2015，and the annual fog days data of Jishou，Huayuan，Fenghuang county (city) from1960 to 2012，the relationship between Ji-Feng-Cha freeway small climate and traffic accidents was analyzed by mathematical statistics and Morlet wavelet method.The results show that the main meteorological factors affecting highway safety are fog and freezing.Foggy weather has low visibility，which is easy to cause vehicle rear-end collision and other collisions.The road is wet and slippery in freezing weather，which is easy to cause traffic accidents，such as rollover，drifting and rear-end collision.The variation rule of the foggy days of zones where Ji-Feng-Cha freeway locates is：Huayuan has a quasi-32-year high cycle and a quasi-3-year small cycle; Jishou has a quasi-2-year small cycle or a quasi-4-year small cycle; and Fenghuang has a quasi-4-year small cycle.

Key words: traffic engineering, meteorology, dense fog, freeze, traffic safety, traffic accident

摘要： 高速公路小气侯与交通事故发生量有一定关联性。利用吉首-凤凰、吉首-茶洞(简称吉凤茶)两条高速公路的4个自动气象站18个月实测资料，高速公路警察2012年4月—2015年6月目测天气信息资料，以及1960—2012年吉首、花垣、凤凰三县(市)的年雾日数资料，采用数理统计和Morlet小波方法分析了吉凤茶高速公路小气候和交通事故的相关关系。研究表明：影响吉凤茶高速公路安全的主要气象因素是大雾和结冰。大雾天气能见度很低，容易发生车辆追尾和撞击交通事故；结冰天气道路湿滑，容易发生翻车、漂移、追尾等交通事故。两条高速公路所处区域雾日数变化规律为：花垣有准32 a的大周期和准3 a的小周期，吉首有准2、4 a小周期，凤凰有准4 a的小周期。

关键词: 交通工程, 气象, 大雾, 结冰, 交通安全, 交通事故