Strength of vapour cloud explosions in a traffic environment: a numerical parametric study

Journal article, 2026

A vapour cloud explosion (VCE) is often deemed one of the most likely scenarios following an unintended release of flammable gas during road transport. Such VCEs produce a blast wave that propagates away from the explosion, potentially causing significant damage and loss of life. The severity of the generated blast loading depends on the VCE’s strength. However, there is currently a noticeable lack of knowledge about the strength of VCEs on urban roads or related settings (such as carparks). This makes estimating the blast load characteristics challenging and imprecise. This study applied computational fluid dynamics to evaluate the strength of several VCE scenarios in a traffic environment. The scenarios consisted of groups of vehicles engulfed by a stoichiometric mixture of propane and air. The influence of parameters, such as the number of vehicles, the separation distance between vehicles, and the gas volume, was investigated using the principles of factorial design. The number of vehicles in the transverse direction had the most significant effect on the resulting overpressure. Indeed, the results indicated that this parameter alone may be sufficient for a conservative estimate of the strength of VCEs in a traffic environment.