为缓解未饱和状态下交通流不确定性对交通信号控制方案实施效果的影响，针 对单交叉路口定时控制信号周期时长优化问题，通过分析比较交通流不确定性、周期时长 设计、控制实施效果三者之间的相互影响程度，依据区间数多属性决策评价方法，在属性 权重完全未知、属性值为区间数且对方案无偏好的情形下，提出了基于相离度和可能度的 交叉口信号周期时长多属性决策模型，最后运用 VISSIM 仿真软件对北京市某相交路口 晚高峰时段进行模拟分析． 结果表明:该周期时长区间决策方法可行有效，且当该交叉口 交通流量比介于［0． 804，0． 909］时，机动车平均延误、交叉口通行能力分别较 Webster 方 法优化了17． 4%与6%． 

  In order to relieve the impact of the uncertainty of traffic flow on the actualization of signal control scheme under a unsaturated condition，this paper initially proposes a new optimization model of cycle length for single intersection by using the timed control． Secondly，through the analysis and comparison of the degree of mutual influence of the uncertainty of traffic flow，design of cycle length and effectiveness of control plan，the interval number multiple attribute decision model of signal cycle length at intersection is proposed on the basis of deviation and possibility degrees of interval number when attribute weights are completely unknown，attribute values are interval numbers，and the method shows no preference． Finally，the intersection in Beijing is simulated for analysis by using VISSIM simulation software． The results show that when the traffic flow ratio is between 0. 804 and 0. 909， the vehicle average delay decreases by 17. 4% and capacity increases by 6%，compared with the Webster method． The method is feasible and effective．