 To alleviate this threat, massive concrete traverses were constructed in the 1880s to isolate each casemate, preventing a shell bursting inside one casemate from affecting its neighbours and causing a cumulative explosion.The construction of concrete gun emplacements on the fort's roof necessitated the installation of circular concrete pillars within the casemates to support the extra weight on the roof.The ammunition lifts were also extended to serve the new roof-mounted guns.