// SetRoadsInArea
void SET_ROADS_IN_AREA(float x1, float y1, float z1, float x2, float y2, float z2, BOOL nodeEnabled, BOOL unknown2);
When this is set to false, all nodes in the area get disabled.
GET_VEHICLE_NODE_IS_SWITCHED_OFF
returns true afterwards.
If it's true,
GET_VEHICLE_NODE_IS_SWITCHED_OFF
returns false.