routine
special (BrE)
armed
foot
Every police car and foot patrol in the area is on full alert.

mounted
reconnaissance
dawn, night
air, army, military, naval, police, security
enemy
border
coastal, harbour/harbor (esp. AmE), maritime, shore
highway (AmE), traffic (BrE)
The highway patrol has sealed off the area.
helicopters used for traffic patrols

safety (AmE) (= to help children cross the street, etc.)

carry out, conduct, fly, go on
The Italians flew regular patrols over the desert.

maintain
They maintain a continuous patrol of the oceans with three submarines.

send out
They sent out four-man patrols to scout the area.

ambush, attack
One soldier was killed when his patrol was ambushed.

aircraft, boat, car, craft, vehicle, vessel
duty

on patrol
police officers on patrol

Patrol is used with these nouns as the subject:
guard, helicopter, officer, police, policeman, submarine, troops

Patrol is used with these nouns as the object:
area, border, neighbourhood, perimeter, sky, street, territory, zone