In this paper, a systematic risk-based transmission line expansion approach is studied. The approach addresses three objectives: load-driven expansion, security-enhancement expansion and risk-based expansion. The first problem identifies transmission expansions necessary to correct inadequacy; the second problem identifies transmission expansion necessary to correct insecurity; the third problem balances economic investment and expected post-contingency consequences. The three problems are addressed using a generalized Benders decomposition algorithm. The approach is illustrated on a six-bus test system.