The Reynolds-averaged Navier-Stokes equations are numerically solved in a segregated manner, along with the Spalart-Allmaras turbulence model. The Galerkin as well as multiple stabilized finite element formulations are derived for the Spalart-Allmaras turbulence model, and tested for robustness. For a turbulent channel flow and a backward facing step case, the Galerkin approach shows to be quite robust by itself, but the multiscale stabilized formulation shows superior robustness in the case of the backward facing step problem, while mostly preserving accuracy.