Rope access or industrial climbing is a form of work positioning, initially developed from techniques used in climbing and caving, which applies practical ropework to allow workers to access difficult-to-
reach locations without the use of scaffolding, cradles or an aerial work platform. Rope access technicians descend, ascend, and traverse ropes for access and work while suspended by their harness. Sometimes a work seat may be used. The support of the rope is intended to eliminate the likelihood of a fall altogether, but a back-up  fall arrest system is used in case of the unlikely failure
of the primary means of support. This redundancy system is usually achieved by  using two ropes - a working line and a safety line.