The assembly line is a production line in which units move continuously through a sequence of stations. The assembly line balancing problem is the allocation of tasks to an ordered sequence of stations subject to the precedence constraints with the objective of minimizing the number of stations. In a U-line the line is configured into a U-shape topology. In this research, a new heuristic, Ant Colony Optimization (ACO) meta-heuristic, and its variants are proposed for the single model U-type assembly line balancing problem (UALBP). We develop a number of algorithms that can be grouped as: (i) direct methods, (ii) modified methods and (iii) methods in which ACO approach is augmented with some metaheuristic. We also construct an extensive experimental study and compare the performance of the proposed algorithms against the procedures reported in the literature.