It is well known, that human factors have an enormous influence on the safe handling of technical systems. Human factors can be described as people's contributions to damaging events. It is the generic term for those psychological and physiological patterns, which are verified to contribute to operational errors in handling machines and vehicles. The human factors concept in relation to road safety, considers road features that influence right or wrong behaviour of the driver. It considers the causes of driver's operational error as the first step in a chain of actions, which may proceed to an accident. Many of the often observed operational errors result from the direct interaction between road characteristics and the driver's reaction characteristics. Because the driver's reaction characteristics cannot be changed, the attention should be focused on a self-explanatory road design. In these guidelines explain the relationship between several road features that trigger mostly unconscious wrong driving reactions. The detailed examples and sketches allow the engineer, to understand the relationship between undesirable road features and operational errors. They can be used as a kind of checklist in the "on-the-spot" investigation of accident points or in Road Safety Inspections. They can also be used to qualify the planning and construction process in Road Safety Audits.