Stopping distance is the sum of thinking distance and braking distance. Drinking alcohol increases a person's reaction time. This increases the thinking distance (the distance travelled before the brakes are applied). As the braking distance is unaffected, the total stopping distance increases.
The total stopping distance of a vehicle is made up of two parts:
- **Thinking Distance:** The distance the vehicle travels during the driver's reaction time (the time between seeing a hazard and applying the brakes).
- **Braking Distance:** The distance the vehicle travels once the brakes have been applied.
Drinking alcohol slows down a person's nervous system and impairs their cognitive function, which leads to an **increased reaction time**.
Because thinking distance = speed × reaction time, a longer reaction time results in a **longer thinking distance**.
The braking distance depends on factors like the train's speed, mass, and the condition of the brakes and track, none of which are affected by the driver drinking alcohol.
Since Stopping Distance = Thinking Distance + Braking Distance, the increase in thinking distance leads to an **increase in the total stopping distance**.
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