riser staircase signal

例句：

1. 1. The elevator has a riser staircase signal to help people navigate the building.
   电梯有一个楼梯信号，帮助人们导航大楼。
2. 2.The fire department uses a riser staircase signal to alert people in the event of an emergency.
   消防部门使用一个楼梯信号来在紧急情况下警告人们。
3. 3. The riser staircase signal is crucial for ensuring safe access to the upper floors during construction.
   上升楼梯信号对于确保施工期间安全到达上层楼层至关重要。