In a railway network, traffic is often perturbed and trains must be rerouted and rescheduled. Doing so in large networks is a challenging task, which has been tackled through various decomposition approaches in the literature. In this paper, we propose an algorithm for managing traffic considering dynamic problem decompositions. It is an asynchronous algorithm based on the decomposition of the problem considering at each time step the smallest possible portion of the network and subset of trains. We prove that this algorithm guarantees to find an overall feasible solution if it exists, for networks with specific characteristics.