Increased global container trade and strong competition are boosting the need for efficient container terminals. Using internal transport resources efficiently reduces transfer times and operating costs. This article addresses the allocation of straddle carriers at a tactical level at intermodal container terminals via optimization and simulation. Our objective is to reduce overall delays at the terminal - with special focus on delays of inland transport modes (rail, road and waterway). We introduce a notation to describe different service strategies and delay criteria and analyze the complexity of different service strategies. A generic mixed integer linear program - that can be easily adapted to different service strategies - models the allocation problem based on a network flow representation of the terminal. We conduct a case study for a container terminal at the Grand Port Maritime de Marseille to evaluate the proposed allocation: we adapt the optimization model to the specific terminal, implement a discrete event simulation model and conduct experiments on actual data. Results show that the allocation proposed by the optimization model reduces delays at the terminal and performs well in a stochastic environment.