Introduction

Good design is the result of collaboration（合作） among many different people. There is a continual interaction(持续相互作用） that produces ideas and tests concepts and finally results in a refined plan. Traditionally, construction professionals were not part of this team. Projects were completely designed by architects and engineers, often with the assistance of construction consultants. Many projects are still produced this way. However as projects become more complex and the need for early completion, construction professional may be brought in during the design process to provide preconstruction（施工前） services. In such cases, their expertise（专业技能） has some effect on the ultimate design.

Preconstruction services can ran from simple cost and scheduling services to integral（完整的，整体的） involvement in the design effort. As an estimator or a scheduler, the constructor is an advisor to the team on cost issues and scheduling issues. He or she may do value engineering studies to produce life cycle cost analysis. Later in the design process, the constructor may help put the work packages together, prequalify（资格预审） bidders.