Crashworthiness Simulations of Roadside Restraint Systems

Abstract The roadside restraint systems have significant influence to severity of the high velocity accidents. Their role is to prevent a vehicle penetration to other road carriageways, as well as to prevent impacts into rigid roadside objects. A main problem lies in the barrier crash stiffness incompatibility with wide classes of the vehicles. The crash simulations of the existing roadside restraint systems impacted by vehicles are performed to identify the influence of various impact conditions (vehicle mass, impact velocity and angle) and structural characteristics of roadside restraint systems (stiffness and geometry) to the crash behavior and severity. The concept of the pyrotechnically adaptive crashworthiness system is discussed focusing on feasible implementation of adaptive system in to the crash barriers. KEY WORDS: roadside restraint systems, crashworthiness, crash simulations, adaptive systems 1. Introduction The purpose of the road restraint system is to prevent a vehicle to veer off the road or its breakthrough to the opposite side of the road with aim to prevent or reduce injuries of road users and damage to certain objects. The road restraint system safety problem is complicated because there are so many variables and external influences, such as weather conditions, increasing traffic volumes, infrastructure deterioration, and variety of others. Numerous studies have been conducted to investigate the relationships between vehicle accidents and the geometric design of the road restraint system [2, 3]. Several run-off-roadway accident studies have examined particular road restraint system features, such as roadway guardrail systems [4-6]. Other studies have examined accidents involving collisions with bridges [7], utility poles [8], side slopes and ditches [9]. Some computational analyses were carried out [1, 9]. These studies have indicated that improvements to the road restraint system geometric design could assure controllable elasto-plastic deformation and crash energy absorption which in turn decreases the decelerations of an impact vehicle and consequently increases the safety of vehicle passengers. The roadside restraints systems have to prevent a vehicle penetration to other road carriageways, as well as to prevent impacts into rigid roadside objects and decrease severity of the high velocity accidents. The problem lies in barrier crash stiffness incompatibility with wide classes of the vehicles. When the barrier is designed to stop heavy vehicles, its stiffness can be extremely dangerous for light city cars whose occupants’ bodies can by loaded by a high-g pulse. The road restraint systems used on Lithuania roads must fulfill requirements of the European EN 1317 standard. This standard defines two kinds of such system: beam (metallic) or parapet (reinforced concrete) ones. The typical construction of beam road restraint systems is shown in Fig. 1 (according to [10]). Fig.1 Construction of road restraint systems (according to [10])