Abstract: This study was conducted to evaluate the safety performance of steel guardrails on sections where roads and railways run parallel, to prevent vehicles from breaching the guardrails and colliding with trains, and to provide engineering application and safety assessment references. Three samples from the Guangzhou-Shenzhen III line road-rail parallel sections were selected. On-site measurements of guardrail geometric parameters (post spacing, post height, beam width) and hardness were taken. Material specimens were sampled and tested in the laboratory for uniaxial tensile properties to determine yield strength and ultimate tensile strength. The guardrails were simplified as beam-column structures to derive a method for calculating impact energy under collision conditions (using a 0.9 mechanical parameter reduction factor). A 3D model of a 1800 kg car and the guardrail was built, and four collision speeds were simulated. The guardrails showed relatively consistent geometric parameters (average values: 200.4 cm, 78.8 cm, 33.5 cm), average hardness 416 (low dispersion), yield strength 678 MPa, and ultimate tensile strength 1018 MPa; calculated impact energy was 50.5 kJ (column impact being the unfavorable scenario), achieving Class One (C) protection. Deformation is controllable at collision speeds of 30 km/h~40 km/h, while speeds above 60 km/h may lead to failure, vehicle overturning, or breaching risks. Existing guardrails have sufficient tensile strength and meet Class One (C) safety standards, preventing vehicles from breaching at speeds within 40 km/h; however, they are non-standard structures, lack general applicability, and require regular inspection. New construction or renovations should refer to current industry standards, and guardrails on ungraded rural roads should follow the fourth-class highway standard.