In the 1980s , a temporary scaffolding bridge was built by the army to enable access for guided tours of the Redoubt .
This was removed in the middle 1990s to prevent unauthorised entry and vandalism .
In the 1980s , a temporary scaffolding bridge was built by the army to enable access for guided tours of the Redoubt , but this was removed in the middle 1990s to prevent unauthorised entry and vandalism .