The subject of this investigation is to develop an accurate low calculation cost Finite Element (FE) model of vehicle impacting roadside safety structures. A W-Beam Guardrail of containment level N2 has been tested under TB32 test conditions by following European Norm EN1317. Full numerical simulations of such crashing models are usually of high calculation costs, the major issues for model simplification used and presented in this paper including: Continuation reduction of guardrail ends; Soil surrogate modelling; Bolted joints simplification; Meshing and Elements definition. By simplifying the small deformation components and detailed modelling of the parts which are exposed to impact loads, the crash test of the guardrail are simulated efficiently and accurately.