In this paper, we address the problem of the modelling and analysing wave propagation in realistic tunnel environments using a numerical model. A 2.5 D TLM based modal algorithm is developed and used to model several tunnel environments, namely an arched tunnel, a metallic tunnel and loaded tunnels with traffic. To analyse wave propagation in these context, a modal nomenclmature is proposed. Depolarisation effects have been demonstrated for arbitrary cross-sections. This effect, often observed during measurement campaigns has been shown with a numerical model.