The Driver's Psychophysical Condition
The vast majority of traffic accidents originate from the human factor. For this reason, it is essential that the driver be in optimal physical and mental condition to ensure safety. Any alteration in these capacities increases the risk on the road.
Fatigue and Sleep
Fatigue is a state of physical and mental tiredness that diminishes the ability to pay attention and react. Driving for long periods, heavy traffic, adverse weather conditions, or a vehicle in poor condition are common causes. Its symptoms include constant blinking, blurred vision, the need to shift in the seat, and frequent yawning.
To prevent fatigue, it is crucial to rest. The general rule is to take a break of 20 to 30 minutes every 2 hours or every 200 kilometres of driving. The only real solution against fatigue is rest.
Sleep is extremely dangerous. "Microsleeps," which are losses of consciousness lasting just a few seconds, can have fatal consequences. The most critical hours for the onset of drowsiness are during the early morning (between 3:00 and 5:00) and after eating (between 14:00 and 16:00).
Alcohol
Alcohol is one of the most serious risk factors. Even in small amounts, it impairs the ability to drive safely. Its main effects are:
- Increased reaction time.
- Reduced field of vision, known as the "tunnel effect".
- False sense of security and overestimation of one's own abilities.
- Increased aggressiveness and impulsiveness.
The only truly safe blood alcohol level is 0.0 g/l. However, the law establishes maximum levels that are essential to memorise:
- General drivers: 0.5 grams per litre (g/l) in blood or 0.25 milligrams per litre (mg/l) in exhaled air.
- Novice drivers (during the first two years) and professional drivers: 0.3 g/l in blood or 0.15 mg/l in exhaled air.
It is important to know that refusing to take the breathalyser test constitutes a crime. Alcohol is eliminated from the body very slowly, and neither coffee nor other remedies speed up the process; only the passage of time is effective.
Drugs and Medications
The consumption of illegal drugs is incompatible with driving. They seriously alter perception, coordination and behaviour. For example, cocaine and amphetamines cause aggressiveness and impulsiveness, while cannabis causes drowsiness and alters the perception of the surroundings.
Some medications, even those prescribed, can affect the ability to drive. Antihistamines for allergies, strong painkillers, or sleeping pills can cause drowsiness and increase reaction time. It is vital to read the leaflet and consult your doctor or pharmacist about their effects.
Illnesses and Emotional State
A simple cold or allergy can decrease concentration and cause drowsiness. Likewise, emotional state directly influences driving. Stress can make the driver more aggressive and impatient. Depression diverts attention to internal concerns, causing the loss of vital traffic information. After a heated argument, it is advisable to stop in a safe place until you regain your composure.
Distractions
Distractions are the main cause of accidents. Diverting attention from the road, even for a few seconds, can have tragic consequences.
The Mobile Phone and GPS
The use of the mobile phone is the most frequent and dangerous distraction. It is prohibited to handle it or hold it in your hand while driving. Only the use of approved hands-free systems is permitted, without using headsets or earphones. Even so, a telephone conversation reduces attention and the ability to react.
The GPS navigator should always be programmed before starting the journey. Handling it while in motion is a serious and punishable distraction. It must be placed in a location that does not reduce visibility or interfere with the airbag.
Other Distractions
Smoking while driving, looking for an object, handling the radio, or eating are other actions that divert the attention necessary for safe driving. Tobacco smoke can also irritate the eyes and impair vision.
The Physics of Driving and Speed
Understanding some basic physical concepts is essential to anticipate risks, especially those related to speed.
Time and Safety Distances
It is essential to distinguish between three key concepts:
- Reaction Time: This is the time that elapses from the moment the driver perceives a danger until they press the brake. The average time is 0.75 seconds, but it increases considerably due to fatigue, sleepiness, alcohol or distractions.
- Braking Distance: This is the distance the vehicle travels from the moment the brake is pressed until it comes to a complete stop. It depends on the speed, the condition of the brakes and tyres, and the conditions of the road (whether it is dry, wet, etc.).
- Total Stopping Distance: This is the sum of the reaction distance and the braking distance. It is the total distance needed to stop the vehicle in the face of an unforeseen event.
Speed as a Risk Factor
Inappropriate speed not only aggravates the consequences of an accident, but also increases the probability of it occurring. The higher the speed:
- Smaller field of vision: The "tunnel effect" occurs, where peripheral vision is lost and only the centre of the road is clearly perceived.
- Less capacity to anticipate: Less time is available to react to unforeseen events.
- Greater stopping distance: Many more metres are needed to stop the vehicle.
- Greater fatigue: Driving fast requires a higher level of concentration, which accelerates tiredness.
On bends, excessive speed causes centrifugal force to push the vehicle outwards, increasing the risk of running off the road.