The process of constructing any edifice has a great number of risks. The construction process itself has dangers; the building materials may be flawed; the construction process can be faulty and the construction site may be unsuitable. The equipment used in construction can be dangerous; tractors can breakdown, cranes can fall and tools can be dropped several stories. Access to the site can be difficult for example the North Sea oil drilling platforms. Worker can take industrial action. Vandals can destroy work that has just been completed.