Uniqueness of projects

Infrastructure projects vary significantly in type, content and size. 

Rates for labour, equipment and materials vary according to market demand, project type and project location. 

Many projects are unique in design, size and/or technology.

As a result, costs are often difficult to compare between projects.  This makes it easier to corruptly inflate costs and hide bribes. 

If people challenge the apparently high cost of a project, reasons can be given such as difficulties in location, design, technology or ground conditions, which are difficult to compare and validate on a cost basis due to the lack of equivalent projects.  This difficulty helps obscure any corruption in the price.