The viaduct which carried the former Colne - Skipton railway line over the Leeds-Liverpool canal at Foulridge will be demolished next week.
A British Rail Property Board spokesman confirmed yesterday that the work on dismantling the structure - said to be only one of two of it's kind left in the country - would start on Monday.
Mr Stuart Parker said that reports received on the condition of the bridge and another one on the line, which closed 26 years ago showed them to be in a dangerous condition and demolition was the only option.
He said the viaduct had to be removed as part of the terms of the Government's privatisation of the railway network, in which British Rail's liabilities have to be disposed of.
Mr Parker said Pendle Council's Buildings Unit had been consulted about the demolition proposals and had given it's consent.
He said, "There is no legal right of way across the bridge and no-one has shown any interest in taking on responsibility for maintaining the bridge, if we were to repair it."