Time-cost trade-off problems of engineering project with running income

For an engineering project with running income, the result of time-cost trade-off problems (TCTP) concerning construction duration is only partly optimal. More cash flow happens during the running period, and the final goal of clients is to obtain the maximal profit across the lifecycle of engineering projects. In some situations, the cost of compressing construction duration even exceeds the increase of income of running period. Therefore, there should be an optimal scheme with the whole profit maximum. The relationship between the income of running period and the construction duration is analyzed in this paper; with the time value of capital taken into account, the mathematic model of TCTP across the running period is developed. Furthermore, the improved genetic algorithms (GA) proposed in this paper are applied to optimize the model. In the end, an example is given to testify the validity of the TCTP across the running period with the time value of capital considered.