Reaction (traffic situation)
According to Sigmund Exner (1846–1926), reaction is the purposeful change in behavior following a stimulus. When it comes to solving traffic accidents , reaction and reaction time sometimes play a significant role.
The shortest reaction time of a motor vehicle driver to a hazard is approx. 0.2 to 0.3 seconds. It becomes noticeably longer due to the need to change gaze, lack of attention or fatigue (see also moment of shock ). In addition to the mental reaction time when braking, there is also the foot transfer time and the response times of the mechanics, which adds up to a total of around 1 second. If the traffic situation requires increased attention and readiness to react, the reaction and brake response time is a maximum of 0.6 seconds (BGH VRS 6, 13).
Response cause - response request
In road traffic in particular, people are forced to react to an oversupply of information and stimuli, of which they can only absorb a fraction. After a factual selection process, only a very small fraction penetrates the highest levels of consciousness .
In order to trigger a reaction, an occasion is required that exceeds a stimulus threshold immediately or after a gradual increase . Only when the reason for the reaction is recognized does the reaction begin, which ends with the change in action. The abnormality (duration of the detection of a danger) is the reason for a reaction and therefore precedes the reaction. The hazard detection time can be very short, only determined by the neurophysiological stimulus conduction when a reflex triggers the reaction. In contrast to some misconceptions, the intensity of the reason for the reaction does not play a role because a reaction can only be initiated at the moment in which the suspicion threshold for the reason for the reaction is exceeded. If the reason for the reaction occurs earlier as a result of an abnormality, this cannot influence the reaction time in any way. An objective response request is only given if z. B. the behavior of the second party is recognizable as a danger.
The question of whether someone drove inattentively must be carefully examined in each individual case, because an interplay between distributive attention (a rough overview of the overall event) and concentrative attention (details are precisely recognized) is necessary in order to be able to cope with complex traffic events. After the period of time, which varies greatly depending on the situation (pedestrians, vehicles, daylight, darkness), until a latent reason for a reaction becomes conspicuous and represents an objective reaction request, the reaction (targeted action) begins. The time it takes to recognize a danger also depends on the experience of the road user and varies greatly depending on the situation. Legal premises must be taken into account when assessing a possible delay in response. What does the driver of the vehicle have to expect in the given situation (e.g. pedestrians on the motorway at night, pedestrians on the protective path)?
reaction time
The reaction time is the period of time between the recognition of a certain reason for a reaction and the start of the (defense) action directed towards it. It is determined psychologically and physiologically and for visual stimuli, ie 80% of our perceptual content, lies between approx. 0.2 and 0.3 seconds. If it is necessary to look (saccade), this alone takes another 0.35 seconds. The reaction time is different for visual, acoustic and tactile stimuli. It varies extremely in the animal kingdom.
The pre-braking time is made up of reaction time, foot transfer time, response time and half the threshold time of the braking system. It takes about 0.8 to 1 second and is colloquially often - incorrectly - referred to as the response time.
The Vorlenkzeit is physiological and vehicle technical reasons by approximately 0.1-0.2 s shorter. The spontaneous tearing of a car takes effect approx. 0.1-0.2 seconds earlier than braking that is carried out "simultaneously".
In Austria, the associated terms are defined based on publications by Fritz Sacher in ÖNORM V5050. The hazard detection time is not included in the pre-braking time. In Germany there is no clear distinction between hazard detection time and reaction, so that different models could be developed.
The diagram shows the entire reaction process from the detection of the hazard as a triggering event to the end of its consequence. Each reaction process and its consequences can be compared using this diagram.
Literature and Sources
- Fritz Sacher in Fucik, Hartl, Schlosser, Wielke (ed.) "Handbook of traffic accidents, part 2", Manz-Verlag Vienna, 2008
- ÖNORM V 5050