Traffic situation and the driving process includes all phases from sensory impressions to action, where reaction time, attention and decision processes play crucial roles for traffic safety.
For more about the time components reaction time, attention time and total time, see Reaction time, attention time and total time.
The driving process: from perception to action
The driving process can be divided into four main phases that describe how the driver goes from perceiving a situation to performing an action:
| Phase | Description |
|---|---|
| Perception | Perceive visual, auditory and kinesthetic information |
| Interpretation | Interpret and understand what the senses convey |
| Decision | Choose appropriate action based on situation and experience |
| Action | Perform the chosen action, for example braking or steering |
For more about attention and interaction in traffic, see Attention and interaction.
For a thorough introduction to risk assessment in practice, see our guide on how you can actively reduce risk.
Reaction time
Reaction time is the period from when you discover a danger until you begin to implement an action. Normal reaction time under ideal conditions is 1–1.5 seconds, but can vary depending on several factors.
Components in reaction time
Reaction time consists of several sub-processes:
| Component | Time (seconds) | Description |
|---|---|---|
| Detection | 0.1–0.3 | Detect that there is a potential danger |
| Identification | 0.1–0.5 | Understand what is happening |
| Decision | 0.1–0.5 | Choose how to react |
| Response | 0.1–0.3 | Perform the physical action |
For a more detailed review of Reaction time and braking distance, see the specific guide.
Factors that affect reaction time
Reaction time can be extended by several conditions:
- Alcohol and medications – can double reaction time
- Fatigue – dramatically increases reaction time
- Mobile use and distractions – weakens attention
- Age – older drivers may react more slowly
- Stress – can both increase and reduce reaction ability
For more about human factors, see Humans in traffic.
Total stopping distance
Total stopping distance includes both reaction distance and braking distance. For detailed calculations and examples of braking distance, see Speed and distance.
Summary
Understanding traffic situation and the driving process is crucial for assessing correct distance, speed and action choices. By being aware of perception, interpretation and reaction, you can reduce risk and drive safer.