Lane change crashes occur when one vehicle attempts to change lanes and collides with another vehicle travelling in the same direction. This crash type is most common on higher volume multi-lane roads (such as motorways and urban arterial roads).

These crashes are common where traffic merges or diverges and where the number of lanes is reduced.

It is also common where there is roadside activity (such as roadside markets or locations where public transport vehicles pick up and drop off passengers).

The severity of the collision between the vehicles of common size is often low, due to low relative speeds. However, if vehicles or road users of different size collide, the consequences can be very severe (e.g. motorcyclist and car, car and truck).

Typical factors which may add to lane change crash risk include:

• Inappropriate speeds.
• Poor pavement skid resistance.
• Unexpected or poor lane drop-offs or merge areas.
• Inadequate length for merging or weaving.
• Roadside activity.
• Poor directional signs or lane markings.
• Poor visibility including ‘blind spots’ and at merging areas and towards diverging areas.
• Driver/rider fatigue.
• Alcohol/drugs/medication impairment.
• Distraction, including inattention due to mobile phone use.
• Information overload (too many driving decisions to be made at once).
• Lack of familiarity with the route.
• Lack of vehicle safety devices.
• Poor condition of vehicle tyres, lights, and brakes.