1.请将以下英文材料翻译为中文 Vehicle-Actuated Sign...
1.请将以下英文材料翻译为中文 Vehicle-Actuated Signals require actuation by a vehicle on one or more approaches in order for certain phases or traffic movements to be serviced. They are equipped with detectors and the necessary control logic to respond to the demands placed on them. Vehicle-actuated control uses information on current demands and operations, obtained from detectors within the intersection, to alter one or more aspects of the signal timing on a cycle-by-cycle basis. Timing of the signals is controlled by traffic demand. Actuated controllers may be programmed to accommodate: • Variable phase sequences (e.g., optional protected LT phases) • Variable green times for each phase • Variable cycle length, caused by variable green times Such variability allows the signal to allocate green time based on current demands and operations. A proper clearance interval between the green & the red phases is also ensured. 2.绘制次干道优先半感应控制流程图,并简要说明其控制方法。 3.简要说明相比定时控制,感应控制有何优缺点。