1, izindleko zokwelashwa eziphansi: izindleko zokuvimbela ukugqwala okushisayo okufakwe nge-galvanized ziphansi kunezindleko zezinye izembozo zopende;
2, okuhlala isikhathi eside: ukushisa okushisayoibha ye-angle yensimbi egayiweinezici zokukhanya okuphezulu, ungqimba lwezinki olufanayo, akukho ukuvuza okubekwe eceleni, akukho ukuvuza, ukunamathela okuqinile, ukumelana nokugqwala okuqinile, endaweni yasemadolobheni, ubukhulu obujwayelekile bokuvimbela ukugqwala obufakwe elangeni elishisayo bungagcinwa iminyaka engaphezu kwengu-50 ngaphandle kokulungiswa; Ezindaweni zasemadolobheni noma ezisogwini lolwandle, ungqimba olujwayelekile olufakwe elangeni elishisayo olufakwe elangeni eliphikisayo lungagcinwa iminyaka engu-20 ngaphandle kokulungiswa;
3, ukuthembeka okuhle: ungqimba oluhlanganisiwe kanye nensimbi kuyinhlanganisela yensimbi, iba yingxenye yobuso bensimbi, ngakho-ke ukuqina kwesembozo kuthembeke kakhulu;