 Because the self @-@ anchored structure relies on the roadway itself to absorb stresses , the suspension cables could not be installed until the roadway was built ; however , until the cables were in place the roadway could not be supported . To resolve this problem , Topham had the roadway built in sections , supported on very tall barges . The barges were floated into place at low tide , and the rising tide was used to lift the sections above the height of the piers . As the tide ebbed , the roadway dropped into place . 
