Factors Which Contribute to Road Crashes — a list of 78

It is a well-known fact that a mere handful of crash-types are the major killers on roads.  These include impaired driving, distracted driving, drowsy driving, speed, vulnerable road users, and so on.  However, although these are indeed the biggest issues, this is not the full story and it is regrettable that people aren’t made more aware of the many other factors and causes.

Only the causes of the crash are listed in the factors shown below. The types of vehicle, direction of travel, resultant damage, etc., are entered in a different part of the overall document.  Photo: Wikimedia Commons.

What follows is an effectively complete list of just the contributory factors for road crashes.  (Other aspects, such as vehicle details, the individuals involved, and the category of the road, are entered in a different part of the document.)

Commonly, there are multiple factors for virtually all crashes and it is these combinations, often occurring ‘coincidentally’ at the same time and place, which can make things happen that too many drivers simply do not anticipate and fail to handle.

Road Environment

  1. Poor or defective road surface
  2. Deposit on road (e.g. oil, mud, gravel)
  3. Slippery road (due to weather)
  4. Inadequate or masked signs or pavement markings
  5. Defective traffic signals
  6. Traffic calming (e.g. speed cushions, road humps, chicanes)
  7. Temporary road layout (e.g. construction zone layout)
  8. Road layout (e.g. bend, hill, narrow lane or road)
  9. Animal or object in road
  10. Slippery inspection cover or pavement marking

Vehicle Defects

  1. Tires illegal, defective or incorrectly-inflated
  2. Defective lights or turn signals
  3. Defective brakes
  4. Defective steering or suspension
  5. Defective or missing mirrors
  6. Overloaded or poorly loaded vehicle or trailer

Injudicious Actions by Drivers or Riders

  1. Disobeyed automatic traffic signal
  2. Disobeyed “Yield” or “Stop” sign or markings
  3. Disobeyed solid yellow line
  4. Disobeyed pedestrian crosswalk facility
  5. Illegal turn or direction of travel
  6. Exceeding speed limit
  7. Travelling too fast for conditions
  8. Following too closely
  9. Vehicle travelling along sidewalk
  10. Cyclist entering road from sidewalk

Driver/Rider Errors or Reactions

  1. Junction overshoot
  2. Junction restart (moving off at junction)
  3. Poor turn or manuver
  4. Failed to signal or misleading signal
  5. Failed to look properly
  6. Failed to judge other person’s path or speed
  7. Too close to cyclist, horse rider or pedestrian
  8. Sudden braking
  9. Swerved
  10. Loss of control

Impairment or Distraction — Drivers/Riders Only

  1. Impaired by alcohol
  2. Impaired by drugs (illicit or medicinal)
  3. Fatigue
  4. Uncorrected, defective eyesight
  5. Illness or disability, mental or physical
  6. Not displaying lights at night or in poor visibility
  7. Rider wearing dark clothing at night
  8. Driver using cellphone
  9. Distraction in vehicle
  10. Distraction outside vehicle

Behavior or Inexperience — Drivers/Riders Only

  1. Aggressive driving
  2. Careless, reckless or in a hurry
  3. Nervous, uncertain or panic
  4. Driving too slow for conditions, or slow vehicle (e.g.  agricultural tractor)
  5. Student or inexperienced driver/rider
  6. Inexperience of driving on the right (e.g. foreign visitor)
  7. Unfamiliar with their vehicle

Vision Affected — Drivers/Riders Only

  1. Static or parked vehicle(s)
  2. Vegetation
  3. Road layout (e.g. curve, winding road, hill crest)
  4. Buildings, road signs, street furniture (e.g. utility poles, etc.)
  5. Dazzling headlights
  6. Dazzling sun
  7. Rain, sleet, snow or fog
  8. Spray from other vehicles
  9. Visor or windscreen dirty, scratched or frosted etc.
  10. Vehicle blind spot

Pedestrians (whether a casualty or uninjured)

  1. Crossing road masked by static or parked vehicle
  2. Failed to look properly
  3. Failed to judge vehicle’s path or speed
  4. Wrong use of pedestrian crossing facility
  5. Dangerous action in carriageway (e.g. playing)
  6. Impaired by alcohol
  7. Impaired by drugs (illicit or medicinal)
  8. Careless, reckless or in a hurry
  9. Pedestrian wearing dark clothing at night
  10. Disability or illness, mental or physical

Special Categories

  1. Stolen vehicle
  2. Vehicle being used in the course of crime
  3. Emergency vehicle on a call
  4. Vehicle door opened or closed negligently
  5. Other – to be specified

Hypothetically, the factors for the crash shown in the above photograph might have been:

  • Stolen vehicle
  • Exceeding Speed Limit
  • Alcohol
  • Vegetation  (i.e. hitting the tree)


SOURCE:  The above list has been created from the standard statistics form in Britain — a long-term, international leader in the gathering of comprehensive crash stats.  The terminology has been modified for American readers.






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