Abstract: The literature review shows that the unreasonable length of spiral transition curve may affect driving behavior and traffic safety.So 39 plane curves and their four-year traffic accidents (2001-2004) of Shang-san Freeway,5 plane curves and their six-year traffic accidents (1999-2004) of Hu-hang Freeway and 6 plane curves and their four-year traffic accidents (2001-2004) of Hang-ning Freeway in Zhejiang Province of China are investigated and analyzed.The result indicates that the accidents on spiral transition curves are not abnormal,therefore it can be considered that the lengths of spiral transition curves in the freeways are reasonable and feasible,and don't affect traffic safety markedly.In the investigated curve radius range [400m,3819.516m],the ratio (A/R) of spiral transition curve's parameter A and circular radius R,is in good minus power relation with R,and its changeable range is in (1/3~1/2) basically,which is in agreement with the conventional knowledge and the recent investigations in literatures.The results can be used as the more specific quantificational references in design.

Key words: spiral transition curve, circular curve, traffic safety, traffic accident, curve illusion

摘要： 对比分析文献表明,不合理的缓和曲线长度会影响驾驶行为和交通安全。调查分析了上三高速公路的39个弯道和2001年-2004年事故资料、沪杭高速公路浙江段的5个弯道和1999年-2004年事故资料、杭宁高速公路浙江段的6个弯道和2001年-2004年事故资料,其中缓和曲线交通事故并没有出现异常现象,表明其缓和曲线长度设计是合理的、可行的,没有对交通安全造成明显影响。在所调查的半径范围[400 m,3819.516 m],缓和曲线参数A与圆曲线半径R之比(A/R)随半径增大而呈现较好的负次幂递减规律,而且其变化范围基本上在1/3~1/2,这与传统认识及最近文献调查相一致。这一基本规律可为设计提供更明确的量化参考依据。

关键词: 缓和曲线, 圆曲线, 交通安全, 交通事故, 弯道错觉