Accident pattern and road safety
The safety of road traffic is a result of multiple effects and a combination of various factors. The accident pattern is determined by a variety of elements such as human beings, the environment, vehicles and traffic operation, geometric and physical elements of the road, traffic law etc. All these elements will to some extent interact with each other. However, particular attention is to be given to the human factor.
Human individuals participating in road traffic
Road traffic requires a wide range of capabilities and competence from human beings. The essential basis of all capabilities in this regard is both of psychological and physiological nature. However, they may be different with each individual regarding the performance of night vision, the sensitivity of sound perception and the ability to deal with stress situations for instance. In general these abilities may also vary significantly with the age of the individual.
Other effects such as heat, fatigue or irritation may come with it. It must be pointed out that the human factor plays the most important role with regard to potential accident spots.
Potential accident spots
Potential accident spots are defined as short sections of road complying with appropriate standards and yet showing up an increased but unexpected accident risk. This is mainly a result of an inadequate risk assessment of the road users involved, whereby the actual risk always exceeds the individually perceived level of risk.
Thus an accident spot may be identified as a section of road that impedes road users from perceiving a potential risk correctly or letting them perceive it too late alternatively. In particular cases the attention of road users may be attracted by events beyond of the traffic operation itself or the actual circumstances are tempting road users to take higher risks. To identify the presence of an accident spot it is essential that the actual design of the road and the outlook of open space are different from how they appear to traffic participants or how they are affecting individual behaviour.
Instruction for the planning and assessment of road segments.
The assessment of potential accident spots was based on extended literature research; furthermore various interviews were held with experts providing practical experience. As accidents do happen rather scarcely and in general must be seen as a result of multiple effects, accident spots will not necessarily draw our attention by a noticeably high number of events. However, crucial accident spots i.e. places or sections of road respectively where accidents really happen more frequently, though complying with design standards, such places may give hints to identify accident spots according to the above mentioned definition.
Principals regarding accident spots
In the course of investigation twenty hypothesis regarding potential accident spots were established and, in addition, were specified by the description of particular cases. Potential accident spots are defined by at least one of the following principals:
- Both the appearance of the road area and traffic operation are not in accordance with each other.
- Some relevant information about the attitude of road users is missing, whether one's own behaviour or else the action of others is concerned.
- The character of section of road ahead may not be clearly perceived.
- A basic change of the road appearance relevant regarding to safety aspects turns up unexpectedly.
- Recognition of other traffic participants is not sufficient.
- Circumstances of traffic operation are too complex
- The outskirts of the road area and actions beyond of traffic operation may attract the driver's attention
- Incentives to road users making them accept higher risks.
In order to avoid or improve potential accident spots, emphasis must be given to both comprehensive and correct driver information and an optimization of the level of capabilities requested from traffic participants. All relevant information for road users should be perceived unconsciously. The arrangement of the road elements and the open space should be fully in accordance with the desired traffic operation rather than bringing it to compliance by means of traffic signals. The attention of traffic participants must strictly be focused on the relevant information regarding traffic operation and diversion by external effects must clearly be avoided.
The improvement of accident spots has to deal with a complex variety of influences that have to be considered such as the interaction of human beings, the environment, the vehicles, traffic operation, the course of the road and legal constraints. A road with a low risk level is fully adapted to the human capability profile and it offers ample tolerance to human failure. Furthermore, it does not induce imprudent behavior but supports the compensation of unsafe actions. This implies that provision is made for the less capable traffic participants such as the elderly and handicapped people in order to achieve a high level of safety.