Patrol, Going Around
noun, verbal noun, の adjective
You patrol and revolve around the block to make your patrol. You're going around patrolling.
じゅんかい
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
天気予報が外れて、巡回中に雨が降り出しました。
The weather forecast was wrong and it started to rain while I was on patrol.