# A Unified Approach for Risk Assessment of Road Crash Barriers Using Bayesian Statistics
## 2 Research on Current Scientific Knowledge
Based on the repeated tests, it can be seen that the new type of prefabricated anti-collision crash barrier has good protective properties even under different working conditions [23]. A study similar to the above-mentioned article addresses the use of mechanical analysis and finite element simulation technology to evaluate the crash barrier and to optimise its construction. A mechanical model of the vehicle and the crash barrier was developed to calculate the force applied when the vehicle impacts the crash barriers. The impact force model was then used to calculate the impact force of a ten-ton truck. The wall thickness and column spacing could be optimised by the results found. The simulation results show that the maximum lateral dynamic deformation of the barrier was 1818 mm, which is consistent with the actual vehicle test results (1600 mm). When the wall thickness of the barrier was increased by 2 mm, the maximum lateral dynamic deformation was 1419 mm; when the spacing of the reinforced columns was reduced to 15 m, the deformation was 1364 mm; after optimization, the deformation was reduced by more than 20%, and the crashworthiness of the barrier was obviously improved [24]. Studies related to the analysis of restraint systems are also carried out on a traffic driving simulator, investigating how drivers adapt their driving trajectory when going through curves where diverse types and heights of barriers are located. The results of the research confirm that the height of the crash barrier has a significant effect on the lateral separation of the vehicle from the device and the impact on the vehicle's control. At minimum crash barrier height, drivers stay closer to the shoulder, while higher crash barriers result in drivers increasing their lateral distance. In the study, the speed of travel around these barriers was simultaneously evaluated, and speed was influenced by both barrier geometry and human factors. An interesting finding was that people adapted differently to the limitation of available sight distance caused by the crash barriers. Men drive faster and behave more aggressively than women [25]. Furthermore, the above study is related, for example, to the identification of the exact type of crash barriers using laser scanning of the road. After the point cloud acquisition, the segmentation method of binary coding was used to voxelize and recognize the crash barriers in the highway scene by using the cluster cutting method. Use of this method makes it possible to distinguish the types of barriers based on their characteristic cuts. The experimental results show that it can effectively identify the types of crash barriers in the point cloud with high accuracy [26]. The next study aims to modify the point cloud obtained from laser scanning and significantly reduce the size of this point cloud to improve further processing and object recognition. Then, segmentation and classification of the crash barriers are proposed as processes dependent on geometric parameters. The results show good discriminative ability in terms of classification compared to other modern methods. Better results were achieved for steel crash barriers than for concrete crash barriers. The method was tested on a set of point clouds obtained by a mobile laser scanner from conventional roads and highways [27]. The results of other studies related to crash barriers are mainly professional works that result in manuals, guidelines and other recommendations for road managers, which encourage the construction or reconstruction of the road network with regard to increasing the safety of its users (e.g., SAFESIDE [28]). Furthermore, there are projects (e.g., SAVeRS [29]) that discuss the appropriateness of using diverse types of restraint systems (crash barrier with beginning element or terminal x crash cushion). Last but not least, there is also research dealing with the selection of appropriate traffic safety improvement measures (i.e., eliminating identified traffic safety defects) based on economic evaluation of effectiveness (e.g., IRDES [30]).