1. A computer-implemented process simulation method having a software engine that calculates resources required to complete a project having a design whose process is to be simulated, said method comprising the steps of: defining a project; defining a plurality of physical resources that are required to complete the project; inputting a plurality of design requirement priority values and a sample design having predefined elements into a computer, which sample design has a process that is to be simulated; defining each substep of the project using a predetermined benefit-trade matrix that comprises a multiple variable lookup table that embodies history data relating to the substep that is indicative of weights of schedule, cost and risk elements for the substep and user-input rating data that comprises values corresponding to the importance of each respective element; defining a logical equation for each substep that computes the time required to complete the project, required resources for the project, and cost of the project based upon data input thereto; inputting weights for schedule, cost and risk elements of each benefit-trade matrix; inputting rating values for schedule, cost and risk elements of each benefit-trade matrix; computing output vectors for each benefit-trade matrix that comprise values corresponding to the respective weight of each element times the respective rating value of each element; at each substep, calculating resources required to complete the project using the vector derived from the benefit-trade matrix associated with the substep, and the design requirement priority values and predefined elements or vector derived from the benefit-trade matrix associated with a previous substep; and outputting data for use in assessing the risk, cost, and schedule associated with decisions made regarding the project.