This is the 14636th most frequent Russian word.
перекрыли
"Blocked" or "shut off" (used for roads, access, or flow).
In this sentence, the word 'перекрыли' is used to indicate the closure or blocking of the traffic.
На дороге перекрыли движение из-за аварии.
The road was closed due to an accident.
Here, 'перекрыли' implies the construction or closing off of a feature, in this case, the dam.
Когда на реке перекрыли плотину, уровень воды поднялся.
When the dam on the river was closed, the water level rose.
'Перекрыли' in this usage denotes turning off or halting the flow of gas.