信控交叉口进口道服务水平与安全的关系研究

Relationship between Level of Service and Traffic Safety at Approaches of Signalized Intersection

信控交叉口的服务水平和安全相关,然而服务水平与不同事故碰撞类型的关系需要深入研究。采集了美国中佛罗里达164个4肢交叉口3年的事故,并重点分析追尾与左转事故。由于信控交叉口服务水平与事故在早高峰、平峰、晚高峰差异较大,且服务水平与事故碰撞类型在同一交叉口不同进口道的分布差异较大,因而在交叉口进口道层面建立随机参数负二项模型研究不同时段服务水平与追尾、左转事故的关系。结果表明,信控交叉口的服务水平与追尾事故显著相关,服务水平由D提高到A,追尾事故减少,并根据追尾事故与服务水平的关系,将服务水平划分为3个等级,A-B最安全,C较安全,D-F最不安全;不同时间段同一服务水平对追尾事故的影响规律不同;服务水平与左转事故不相关。

It is generally agreed that for signalized intersections,level of service(LOS)is related to traffic safety.However,this relationship needs to be further studied for different crash collision types.Crash data are acquired over a three-year period from 164 four-legged signalized intersections in the Central Florida area,and rear-end and left-turn crashes are selectively analyzed.Since intersection LOS and the crash type frequencies are different for morning peak,midday,and afternoon peak hours,and are different for approaches within one intersection,random parameter negative binomial models are developed to estimate the LOS-safety relationship across different time periods for rear-end and left-turn crashes separately at approach level of the intersections.Results showed LOS is significantly associated with rear-end crashes,and rear-end crashes decreased at approaches of signalized intersections operating from level D to level A(A is the highest and F is the lowest in LOS).According to the relationship between rear-end crashes and LOS,which is classified into three levels,A-B is the safest,C is safer,and D-F is the least safe.The relationship of a specific LOS to rear-end crashes varies across different time periods.LOS is not associated with left-turn crashes.