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Lorry braking distances

Despite having many more tyres in contact with the road, the additional weight of an HGV means that stopping distances (including reaction time) can be 50% further than a car in similar conditions. On a dry road, a car will stop from 55mph in around 80 metres, but a lorry could take around 120 metres.

If the lorry is travelling at 60mph, the stopping distance extends to around 132 metres. It’s only 12 metres more, but at the 120m mark, the lorry is still travelling at almost 30mph. This is the equivalent amount of kinetic energy as a passenger car travelling at over 150mph.

The lorry that was doing 60mph is still travelling at 30mph when the first lorry has stopped

If the conditions are not perfect, the driver is tired or distracted or the visibility is poor, overall stopping distances will be even longer which could lead to crash causing major damage and trauma.

When a vehicle crashes, it suffers a rapid change in speed. This is usually a deceleration as it hits something solid or moving in the opposite direction. However, the bodies inside the vehicle want to continue moving in the same direction and this creates the potential for injury. The severity of injuries is influenced by the speed of the crash itself; speed might not cause the crash, but it certainly affects the outcome.

Lorry drivers are used to looking further ahead of them. It is easier because they have a better vantage point, being higher up, but it’s also important because it gives them that advantage of seeing a developing hazard earlier and reacting sooner to mitigate that 40-metre braking disadvantage they have compared to cars.

How can car drivers help lorry drivers?

If you’re a car driver, bear in mind that a lorry will leave more space in front of it and if you close that gap, you’re taking away the driver’s options if an issue unfolds ahead. If you’re approaching a set of lights, slower traffic or where two lanes merge into one, give lorries space. Clearly indicate your intentions so that the lorry driver can drop back – three seconds of indication is the minimum.

As lorry drivers have blind spots directly in front of their vehicle, position yours so that the lorry driver will be able to see your indicator.

Diagram showing semitrailer blind spots looking back from the front of the cab

Darren has owned several companies in the automotive, advertising and education industries. He has run driving theory educational websites since 2010.

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