# Using Lp / Ip Hybrid Method For Time Cost Tradeoff

973 Words Dec 7th, 2015 4 Pages
Using LP/IP Hybrid method for time-cost tradeoff
a. Suggested method
Obtaining a good and nearly optimal solution with a reasonable amount of computational effort is the major motivating factor for this method. Integer programming can find the exact optimal solution, but it is computationally intensive.

The LP/IP hybrid method is a hybrid approach uses:
(1) Linear programming to create a lower bound of the lowest direct cost curve efficiently; and (2) Integer programming to find the exact solutions.
Following describe the formulation of linear and integer programming models. Examples are given to demonstrate how to formulate the mathematical models. Linear programming algorithms, such as simplex method, can then be used to find the optimal solutions. Much commercially available linear programming software, such as Lindo, can perform the task very efficiently. The formulation of the objective function and constraints for linear programming, however, is time-consuming and prone to error. From the writers ' experience, formulating the objective function and constraints rarely succeeds without several revisions. For large CPM networks, the effort to check and verify the formulation could be phenomenal. The convex hull method in conjunction with linear programming establishes the lower bounds for time-cost relationships of a project. These lower bounds give construction planners a general idea of the project time-cost relationship. From these lower bounds, construction…