Cov qhov rooj tua hluav taws tshwj xeeb yog siv los cais qhov hluav taws kub hauv kev tsim vaj tsev. Thaum muaj hluav taws kub, tib neeg tuaj yeem tau txais txoj hauv kev khiav los ntawm qhov rooj hluav taws. Cov qhov rooj hluav taws feem ntau yog nyob rau hauv kaw kev khiav tawm stairs, elevators, pipeline qhov dej, thiab lwm yam.