In this paper, a method based on the Davidson-Fletcher-Powel (DFP) optimization algorithm to design a decentralized controller for a traffic network is presented. The controller designed with this method shows decoupling property and high performance. It is also compared with two other optimization algorithms, Broyden-Fletcher-Goldforb-Shanno (BFGS) and steepest descent. The performances of the BFGS and DFP algorithms are quite similar, but the steepest descent method does not converge to the desired decentralized structure at all. Simulation results confirm the validity of the analytical work