The development of the effective and economical lightning protection measures is very important for railway signalling systems because lightning damage causes railway transportation disruption. This paper proposes a calculation model for lightning overvoltages on railway level crossing equipment. The calculation model consists of a propagation model of lightning surge along the rails and an equivalent circuit model of equipment. The authors validated the calculation model by comparison with field test results. This model is applicable for quantitative estimation of lightning protection measures of railway signalling equipment.