Rope off
Definition 1 of 1
Pro Tip 1/3Safety Measure
Used when an area might be dangerous or to prevent disturbance to something sensitive. 
The construction site was roped off for safety.
Pro Tip 2/3Temporary Access
Indicates the area is usually accessible but is temporarily restricted. 
They roped off the park during the festival.
Pro Tip 3/3Crime Scene
Commonly used by police or investigators to preserve a crime scene. 
Police roped off the alley as a crime scene.