Dredgers show the side on which you should pass by displaying two diamond shapes, one above the other (at night two all-around green lights).
Izigutyuli zibenisa icala emawudlule kulo ngekubenisa izakheke zedayimeni ezibini, esinye phezu kwesinye (ebusuka izikhanyisele ezibini eziluhlaza -- ezigqiba ukubuku benke).