Since November 2015 there is an EU-wide legal requirement for new two- and three-axle heavy trucks to be equipped with the automatic emergency brake function. The aim of this is to reduce accidents in which a truck drives into the back of a vehicle in front of the truck, an accident scenario that accounts for about 20% of all road accidents involving trucks.
At present, legislation requires that the emergency braking system must reduce the truck´s speed by 10 km/h (6mph). Next year, this will be tightened to 20 km/h (12.5 mph).
“It’s great that the legislation is becoming stricter, but I still feel the legal requirements are too low,” says Carl Johan Almqvist, Traffic & Product Safety Director at Volvo Trucks. “For example, if you are driving at 80 km/h (50 mph) when the emergency braking system is deployed, you need to cut your speed by far more than just 20 km/h (12.5 mph) to avoid a massive collision if the vehicle in front has come to a standstill.”
Volvo Trucks has developed a system that goes well beyond both current and future legal requirements. This system, which was introduced in 2012, focuses primarily on alerting the driver to the risk of a collision.
“In many cases this is enough for the driver to quickly assess the situation and avoid an accident,” explains Carl Johan Almqvist.
The emergency brake is only used if it is absolutely necessary and it is deployed extremely quickly. The braking speed – or retardation to use the correct technical term – is about 7 m/sec2, which is on par with what many passenger cars can manage. In practice this means that the truck’s speed can be cut from 80 to 0 km/h (50 mph to zero) in about 40 metres (130 feet).
The system monitors the vehicles in front with the help of camera and radar technology and functions irrespective of whether it is sunny, misty, foggy or dark. If there is a risk of collision, the driver is alerted via gradually escalating light and acoustic signals. If the system does not detect a response from the driver, the truck automatically starts braking gently. However, if the driver still does not respond, the emergency brake is deployed until the vehicle comes to a complete standstill. After a further five seconds without any movement of the steering wheel or other reaction, the handbrake is automatically engaged – a safety measure designed to prevent the truck from rolling if the driver is in shock or unconscious.
When the emergency brake is deployed, the brake lights start flashing to warn vehicles to the rear, and when the truck’s speed drops to 5 km/h (3 mph), flashing emergency warning lights are also activated.
Volvo’s system also functions on winding roads and can differentiate between roadside guard rails and genuine obstacles, such as other vehicles including motorbikes. In order to gain the full benefit of the system, it is essential to ensure that all functions, such as the ABS brakes, are activated on both truck and trailer.
Considering the short period that has passed since the introduction of emergency brake legislation, it will take some time before its positive effects are reflected in accident statistics. However, Volvo Trucks is convinced of the benefits of the emergency braking system and other active safety devices.
Carl Johan Almqvist concludes, “Our active safety systems are part of a holistic solution that clearly helps reduce risks in traffic, but it is important to bear in mind that technology cannot do the job alone. A safe traffic environment requires active interaction between all road users. An experienced, attentive driver who handles their vehicle responsibly is still the best form of accident prevention.”