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Transmission expansion planning provides an essential measure for long-term congestion management. Congestion-driven planning method becomes one of the new challenges under deregulated environment. With POOL transaction pattern being the basic investigation background, the fuzzy congestion management models for bilateral auction market mode and single-buyer market mode are set up first in this paper. The soft constraints of line power flow limits, and market participants' bidding curve coefficients considering possible strategic bidding, are all described in form of fuzzy membership functions. Second, based on the maximum membership rule and maximum entropy principle, the fuzzy optimal congestion management problem is solved. New sensitivity indexes to select to-be-built or to-be-upgraded lines are defined for the two market modes respectively. They describe the compromise between congestion relieving impact and investments, and make the problem of transmission network planning solved fast, simple and heuristic. Test results illustrates that the fuzzy congestion-driven and sensitivity analysis based heuristic transmission network planning method for POOL transaction pattern presented by this paper is robust and practical under the deregulated environment.