# Risk Assessment of Fixed Obstacles along Roads
## 1 Basic Knowledge Related to the Issue  
One of the main priorities of most countries is to promote the development of security, in all human sectors. Transport is undoubtedly one of these sectors. Improving safety in transport has been set out in the White Paper on European Transport Policy [1], in particular in the context of Vision 0 [2]. Within the Czech Republic, the desire to reduce traffic accidents and improve road safety has also been reflected in the national road safety strategy. This strategy sets safety assessment criteria inspired by the above-mentioned international document [3]. Because it is a strategic European document, it clearly specifies requirements for all EU Member States. Therefore, it can be concluded that the presented research, although conducted in the conditions of the Czech Republic, can be generally applied not only to other EU Member States but also in a global context. The issue of the occurrence of fixed obstacles in the road safety zone can be described as a global traffic safety problem. Of course, it is necessary to take into account local specifics at the individual State level. Proof for the necessity of constant attention to safety evaluation can be found in numerous psychological research studies [4, 5] stating that a human causes an error event approximately every 10 thousand tasks (for comparison, e.g., for machines, an error eventper 100 million tasks is calculated). The design of transport infrastructure must reflect this fact. Roads must be comprehensible to all users, who must always easily understand how to use the infrastructure. If this is not the case, there is a high probability of conflict situations occurring, resulting possibly in a traffic accident. For this reason, it is important to ensure that the road fulfills two fundamental principles. These are the principles of self-explanatory and forgiving roads. A self-explanatory road is a concept that means that the design elements and the quality of their construction provide the road user with sufficient clear and unambiguous information to behave and make safe decisions when using the road. This layout prevents the occurrence of an accident. Forgiving roads are to some extent able to eliminate (forgive) driver fault or non-standard vehicle behavior as a result of a fault. These are such elements of the arrangement that eliminate or mitigate the fatal consequences of a traffic accident. Research into the development of a deformable culvert face, for example, demonstrates the specific possibility of implementing the forgiving road principle in the area of fixed obstacles [6; 7; 8]. The risk of a manned vehicle getting off the road can never be 100% eliminated. This may be caused, for example, by an avoiding maneuver, loss of control of the vehicle or a collision with another motor vehicle. If such a situation occurs, the occupants can easily become victims of serious consequences, e.g., due to collision with fixed objects along the road. For this reason, road managers are generally required to maintain a \"safety zone\" along the road in which the direction of the vehicle can be corrected just in time or stopped safely. Its width is not constant but depends on the maximum permitted speed, the directional alignment and the position of the road in relation to the surrounding terrain (fill slope, cut slope) [9]. To assess the level of road safety, the knowledge set out in the methodologies for the implementation of safety inspections is used [10; 11; 12; 13; 14]. The road safety assessment can vary significantly from country to country, depending on the maturity of the country in the field of road safety assessment, economic possibilities and the will or priority to solve this topic. However, all knowledge related to the analysis of fixed-obstacle risk is provided in the road safety inspection methodology.