Ability to conceal corruption: Concealed work

Many components in an infrastructure project will be concealed by other components.  E.g.:

• structural steel may be concealed by concrete
• brickwork may be concealed by plaster
• engineering components may be concealed in casings
• roof structures may be concealed by cladding. 

As a result, an enormous dependence is placed by the industry on individuals certifying the correctness of the work as it progresses and before it is concealed. 

This provides opportunities to conceal the incorrect work from the certifiers, or to pay bribes to certifiers to approve defective or non-existent work.

For example, a foundations contractor only places 50% of the required amount of structural steel into the foundations excavation, then pours concrete into the foundations when the supervisor is not present, or alternatively bribes the supervisor to overlook the deficiency.  Once the concrete has been poured into the foundations, it is no longer possibly to visually inspect the quantities of steel in the foundations, as the steel is covered by the concrete.  The contractor can then fraudulently claim payment for 100% of the steel, even though it has only supplied 50%.