Linear induction motors (l.i.ms) have many possible applications, ranging from low-speed cranes to high-speed ground-vehicle propulsion. However, in average and high-speed l.i.ms, the end effects cause considerable deterioration in the performance in low-slip regions. The paper introduces the concept of realistic goodness factorGR, which takes into account by appropriate coefficients the airgap leakage, secondary sheet skin effect and transverse edge effects. Approximations involved in obtainingGRare discussed and essentially a one-dimensional analysis is used. It is shown that the end-effect influence can be expressed as a function ofGR, slip and the number of poles. An optimum goodness-factor criterionGoto aid an optimum l.i.m. design is proposed. It is demonstrated thatGocan be achieved in practice, and leads to a good-performance, low-weight l.i.m. Numerical results based on a full-size existing l.i.m. test vehicle are given.