Rock is quite a different material from the soils the dredging contractors are used to deal with. The rock cutter dredgers can handle fairly difficult ground and apart from rock they dredge also weathered rock and difficult soils. Dredging contractors are highly dependent on the site investigation reports available to them when they are assessing a project at the tendering stage. Site investigation is needed to define the geological factors of influence on a dredging project and to assemble geotechnical data. Stone stresses that: "the most frequent criticism of any dredging project that has been executed is that there is insufficient soil information. The central purpose of the research project was to try to achieve an improvement in the prediction of rock cutting tool wear. The chapter also presents an overview of the key concepts discussed in this book.