Most RTOs use a form of adjusted production cost (APC) savings to judge economic benefits of potential transmission projects which may not fit competitive electricity markets if it only measures generation cost, and ignores congestion cost. Congestion cost is due to price separation between generation and load, which can significantly impact electric consumer costs. This paper is going to compare the current MISO, SPP and PJM APC methods firstly. A new cost evaluation method is then proposed to balance the benefits between utilities and consumers. Simulation in the IEEE14-bus test system shows that the proposed new metric works well for system congestion relief and cost estimate for the whole society.