丈量員的主要職責是(a) 協助測量主任（工程）或土地測量師職系人員實地進行測量工作；(b)測量設備、工具及物料的準備、保管、運送以及簡單的維修工作，以供實地測量之用；(c)確保測量設備儲存室整潔；以及(d)有需要時督導一級及二級工人，並協助培訓一級及二級工人。（註：獲取錄的申請人或須不定時工作，以及在本港任何地區工作，包括山區及崎嶇不平的地區。）

A Chainman is mainly deployed on (a) assisting a member of the Survey Officer (Engineering) or Land Surveyor Grades to carry out survey work in the field; (b) undertaking the preparation, care, transportation and simple maintenance of survey equipment, tools and materials for field survey operations; (c) maintaining the order and cleanliness of the survey store; and (d) supervising Workmen I and Workmen II as required and assisting in the training of Workmen I and Workmen II. (Note: Chainman may be required to work irregular hours and work in any part of the territory including hilly and rugged area.)