Tunnel accidents with transports of dangerous goods may lead to explosions. Risk assessment for these accidents is complicated because of the low probability and the unknown, but disastrous effects expected. Especially the lack of knowledge on the strength of the explosion and the consequences for the tunnel user, the tunnel lining and the consequences for the surroundings and adjacent structures, hampers the quantitative risk assessment. Decisions on the routing of the dangerous goods transports cannot be supported by quantitative risk analysis (QRA) without knowledge on the explosion mechanisms and the ability to predict the explosion strength for accident scenarios. The common knowledge proved to be insufficient for this risk evaluation. Based on the expertise on explosions, reactive gas dynamics and CFD expertise, TNO developed engineering models to quantify the explosion load and consequences. This paper presents (i) the different types of explosions and the related scenario conditions, (ii) the explosion models and representative explosion loads and (iii) illustration of the consequences. A comparison with the guidelines given in the Eurocode is made and shows that these guidelines are not suitable for risk assessment and tunnel design. The engineering models presented in this paper give the required input for QRA. It is shown that a variety of explosion strengths may occur and that not all explosion scenarios lead to disastrous effects. For the transport of dangerous goods through tunnels a wide scope of explosion scenarios has to be and can be considered.