3.3 Causes of Road Traffic Crashes

Why Crash Causes Matter on the FRSC CBT

The FRSC Driver's Licence CBT is not only a signs-and-signals quiz. It tests whether you understand why crashes happen and what a responsible driver does to prevent them. The Nigeria Highway Code and FRSC public education consistently organise causes into three broad buckets:

1. Human factors — what people do (or fail to do)
2. Mechanical factors — what is wrong with the vehicle
3. Environmental factors — road, weather, light, and surroundings

Real crashes are often multi-factor. A tired driver (human) on bald tyres (mechanical) in heavy rain at night (environmental) is a classic fatal combination. Exam questions may ask you to classify a cause or to choose the best preventive action. Parade knowledge from the previous sections is the practical antidote to many mechanical causes; defensive driving (later chapters) is the antidote to many human and environmental traps.

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Human Factors: The Largest Slice of Preventable Harm

Most analyses of Nigerian road trauma place human behaviour at the centre. Knowing the categories helps you answer CBT items and audit your own habits.

Speeding and inappropriate speed

Speeding is not only "exceeding the posted or default limit." It also means driving too fast for conditions — wet roads, markets spilling into the carriageway, school zones, or poor visibility — even if the speedometer is technically under a dry-weather limit. Higher speed:

• Shortens the time available to search, identify, and react (SIPDE)
• Increases stopping distance dramatically
• Raises crash energy; injury severity climbs with speed

Default limits you will study in detail later (for private cars, commonly 50 km/h built-up, 80 km/h highway, 100 km/h expressway) exist because physics does not negotiate. FRSC enforcement of speed limiters on many commercial vehicles underlines how seriously speed is treated as a crash generator.

Distraction and phone use (UPD)

Use of Phone while Driving (UPD) is a named enforcement and education theme in Nigeria. Looking down at a screen for two seconds at 80 km/h means travelling a long distance effectively blind. Distraction also includes:

• Texting, video calls, and scrolling
• Handheld calls (even "quick" ones)
• Operating complex dash apps while moving
• Turning to argue with passengers or discipline children without securing the vehicle
• Eating, grooming, or searching the floor for dropped items

The prevention rule is simple enough for a CBT stem: if it takes your eyes, hands, or mind off the driving task, it is a human crash factor. Pull over safely to use the phone.

Fatigue and driving hours

Fatigue slows reaction time similarly to alcohol impairment. Long night runs, early departures after poor sleep, and monotony on dual carriageways produce lane drift, micro-sleeps, and rear-end collisions. Warning signs include heavy eyelids, frequent yawning, wandering thoughts, and not remembering the last several kilometres. The correct response is stop in a safe place and rest, not another energy drink while pushing on "just one more hour."

Drink- and drug-impaired driving (DUI)

Driving Under the Influence of alcohol or drugs — including some prescription medicines that warn of drowsiness — is both illegal and a major human cause of crashes. Impairment degrades judgement, vision, coordination, and risk perception. FRSC and police enforce DUI rules; the Highway Code position is absolute for candidates: do not drive impaired. Arrange another driver, delay the trip, or use alternative transport.

Recklessness, aggression, and rule-breaking

Recklessness covers intentional dangerous behaviour: racing, dangerous overtaking on blind bends, running red lights, forcing right-of-way, wrong-way driving, and intimidation. It is distinct from a single honest mistake, but both kill. CBT items often pair recklessness with respect for other road users and right-of-way rules.

Non-use of seat belts and restraints

Failing to wear seat belts does not always "cause" the first impact, but it massively worsens injury outcomes and can turn a survivable crash into a fatality when occupants strike the interior or are ejected. Because belts are mandatory for all occupants, non-use is treated as a serious human-factor failure. Child restraint mistakes (infant on an adult lap, child under 12 in the front seat) fall in the same family.

Human-factor summary table

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Mechanical Factors: When the Vehicle Betrays the Journey

Mechanical factors are defects or deficiencies in the vehicle that contribute to a crash or prevent successful avoidance. Many are detectable during parade — which is why Chapters 3.1 and 3.2 sit next to crash causes in this guide.

Worn or defective tyres

Tyres below 1.6 mm tread, with bulges, or badly under-inflated, produce blowouts, aquaplaning in rain, and long wet stops. A sudden blowout at speed can throw an unprepared driver into oncoming traffic or a ditch. First parade is the primary control measure.

Failed or weak brakes

Brake fluid leaks, worn pads/linings, air in hydraulic lines, and defective handbrakes turn normal hazards into collisions. Third parade brake tests exist to catch spongy or pulling brakes before traffic density rises.

Lighting and electrical failures

Driving without working headlamps, rear lamps, or brake lights — especially at night or in rain and Harmattan dust — means other road users cannot see you or your intentions. Unsignalled turns from dead indicators cause junction crashes. First parade lamp checks are mechanical-factor prevention.

Steering, suspension, and structural defects

Excessive steering play, broken suspension after pothole abuse, insecure loads, and doors that fly open are mechanical contributors. Overloaded vehicles (common with goods and some passenger operations) lengthen stopping distances and raise rollover risk — a mechanical/loading issue with human decision roots.

"Deficient vehicle" as an exam phrase

When a question says a crash was caused by a deficient vehicle, look for options describing unroadworthy condition: no brakes, bald tyres, no lights, defective steering — not weather and not a texting driver (those are environmental and human).

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Environmental Factors: Conditions Outside Driver and Machine

Environmental factors are external conditions that raise risk. They do not excuse reckless driving; they demand adjustment.

Rain and wet surfaces

Tropical downpours reduce visibility, hide potholes under water, and promote aquaplaning when tread cannot clear water. Stopping distances grow; painted lines get slippery. Prevention: reduce speed, increase following distance (often to four seconds or more in the wet), use low-beam headlamps in heavy rain, and avoid sudden steering inputs.

Dust and Harmattan haze

Harmattan dust can cut visibility like fog. The defensive response mirrors poor weather: slow down, low beams, longer gaps, and readiness to meet vehicles without lights. High beams can backscatter in dust and worsen glare.

Poor roads, work zones, and design limits

Potholes, eroded shoulders, missing signage, sharp unmarked bends, and construction diversions are environmental realities on many Nigerian routes. Slow early; do not swerve violently into other lanes without checking. Environmental hazard does not justify entering a yellow box blocked by congestion or overtaking on a blind crest.

Night and low light

Darkness hides pedestrians, animals, broken-down trucks, and unlit motorcycles. Drive so you can stop within the distance illuminated by your headlamps. Dim to low beam for oncoming traffic and when following closely. If dazzled, look toward the right edge of your lane as a guide rather than staring into high beams.

Animals, markets, and roadside activity

Livestock, dogs, street trading, football near the carriageway, and people boarding buses create sudden environmental hazards. Expect the unexpected near villages and urban corridors. Horn use may warn, but speed reduction is the real control.

Environmental summary

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Multi-Factor Crashes and the Prevention Mindset

Scenario: Combined causes

A bus with worn tyres (mechanical) is driven at high speed by a fatigued driver (human) through a night rainstorm (environmental). When a car ahead brakes, the bus cannot stop and jackknifes. Investigators will list all three factor types. On the CBT, any of those factors might appear as the "primary" cause depending on the stem — read carefully.

Scenario: Parade would have stopped it

A private car's brake light is out (mechanical). A following driver assumes the car is coasting and collides when it brakes hard in a market queue. First parade would have revealed the dead lamp. This is why crash-cause study sits in the same chapter as parade.

Link to defensive driving (preview)

Defensive driving, as defined in the Nigeria Highway Code tradition, is driving to save lives, money, and time despite conditions around you and the actions of others. Crash-cause literacy feeds that definition:

• Control human factors in yourself: speed, attention, sobriety, rest, belts
• Control mechanical factors through parade and maintenance
• Respect environmental factors by changing speed, gap, and route plans

You cannot eliminate every risk on Nigerian roads, but you can refuse to stack risks on top of each other.

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CBT Classification Practice Tips

When a question asks for the type of cause:

• Driver behaviour, impairment, distraction, speeding, no belt → Human
• Tyres, brakes, lights, steering defects, unroadworthy vehicle → Mechanical
• Weather, light, road condition, animals, visibility from dust/rain → Environmental

When a question asks for the best prevention:

• Match the fix to the factor (rest for fatigue; repair for brakes; slow for rain)
• Prefer options that stop the journey from starting unsafe (parade) over heroic mid-crash manoeuvres
• Reject options that blame only "bad luck" when a clear human or mechanical failure is described

Bottom line: Human, mechanical, and environmental factors are the Highway Code map of crash causation. Learn the map, connect it to first–second–third parade, and you will both pass more CBT items and drive with a genuine prevention mindset.