Efficiency of impact pendulum tests for road restraint systems: A review and evaluation

Full-scale crash testing is the definitive approach for evaluating the crashworthiness of road restraint systems (RRS), but it requires specialised proving grounds, instrumented vehicles, extensive safety infrastructure, and substantial financial and logistical resources. Impact pendulum testing has therefore been widely used as a repeatable and comparatively economical surrogate during preliminary structural assessment, design development, and numerical-model validation. However, technical information on these systems remains dispersed across journal articles and technical reports. This review critically evaluates the application, capabilities, and limitations of impact pendulum systems for RRS and consolidates their principal design and testing characteristics. The study combines a bibliometric assessment of Scopus and Web of Science records updated through 2026, supported by VOSviewer analysis, with a detailed comparison of 29 RRS-related pendulum-system configurations identified in the literature. The systems were examined in terms of impactor material and geometry, mass, suspension arrangement, impact nose, impact height and angle, initial height, impact energy and velocity, instrumentation, performance indicators, applicable standards, and numerical simulation methods. The review shows substantial variation in pendulum design and test conditions, while rigid impactors, predominantly perpendicular impacts, and dynamic measurements using accelerometers, load cells, strain gauges, and displacement or velocity sensors are common features. LS-DYNA is the most frequently used numerical tool for calibrating and validating impact models. Overall, pendulum tests are particularly useful for structural-response screening, comparative assessment, component-level impact evaluation, and finite element model calibration and validation. Nevertheless, they cannot fully reproduce vehicle trajectory, occupant risk, post-impact stability, or the complete kinematics of oblique full-scale collisions and should not be regarded as a substitute for certification-level vehicle crash testing. Future research should prioritise standardised test procedures, adjustable impact conditions, more representative impactor configurations, and closer integration of pendulum experiments with validated numerical simulations, including applications addressing the evolving characteristics of electric vehicles.