Currently, estimations of the crack width in the deck slab of bridges given by codes of practice are based on either theoretical or empirical approaches considering mainly the monotonic loading behaviour. However, cracking in reinforced tensile members is highly influenced by the loading history (including both the loading and unloading processes). The irreversible non-linear behaviour of bond and the tensile response of concrete induce residual cracks of non negligible width. This paper investigates the influence of this phenomenon and presents a physical model describing it. An analytical model is developed and its results are compared to various tests with good agreement. Finally, a simple design formula is derived and recommendations for its application to practical cases are proposed.