A loaded tipper lorry traveling in the early hours of the morning on the M4, overturned onto its side at Junction 4. The driver sustained minor injuries and there was a diesel spill to the highway. No other persons were involved or injured.

The following root causes were identified;

• The vehicle stability when carrying approximately three-quarters load of planings were not fully considered, increasing rollover risk during braking and steering.
• Speed was not reduced sufficiently early on approach to the bend.
• End-of-shift/night-time driving contributed to fatigue, reducing alertness, cognitive processing, and forward planning.
• Fatigue and perceived time pressure impacted decision-making.

Local

Driver removed from the company's operations and a lifetime ban applied.

National

• Ensure drivers adjust their driving style and speed to suit the road and environmental conditions.

• Increased awareness of night-time driving risks.

• Reinforcement of the need for early speed reduction and forward planning when approaching motorway slip roads.

• Improved understanding of vehicle stability risks.

• Ensure sufficient breaks and rest periods are adhered to.