What type of project do you have in mind? Contractors usually specialize in different areas,and you will find that major projects like the one you mentioned may have many different components and require different types of specialist contractors. For instance,I recently supervised works for a high rise building where we had close to 20 contractors,with each handling different aspects of the project. However,for a project to be successful,you need to start by employing a consultant,who will prepare designs and documentation,long before the contractor comes in. This is where professionals like my self come in. In simple terms,I know the nuts and bolts of building and civil projects after many years of experience. Drop a line if you require personalized advise (check my profile for e-mail).