This paper reports on a procedure to find shortest paths and an application on the route design problem in a time-dependent network. In the application on the real network, the data, which are obtained with real-time observations, are integrated with forecast data to define the costs on non-observed network elements that were obtained from a dynamic traffic simulation. The real case application is performed in emergency conditions and the aim is to optimize emergency vehicle routes (defined as a path succession) to reduce intervention times.