Fleet News

Softening the blow of accidents

IN the event of a potential crash, no-one can guarantee drivers will react in the same way. Some might be able to steer the car around an object while braking while others might be able to correct a skid. Others may panic and freeze, hoping the impact will be as small as possible.

But what if the car they were driving was able to react to incidents and help keep casualties to a minimum?

A new generation of active safety features are aimed at reacting to potential incidents, and some of them are already on the road in fleet vehicles. Drivers of the Nissan Primera 2.0-litre T-spec will be familiar with the merits of Intelligent Cruise Control, which reduces speed and even brakes if the car gets too close to the vehicle in front. Previously, this was the preserve of drivers of top-of-the-range Jaguar and Mercedes-Benz models.

Cruise control using radar to position the car is the first step for automatic safety systems on vehicles and, called Distronic, is standard equipment on some of the latest Mercedes-Benz models. The next step is PRE-SAFE, which has been installed after the company's researchers found that in two-thirds of collisions there was enough time to activate additional protection measures.

Skidding, emergency braking or a sudden evasive manoeuvre preceded these situations. This 'window', which might last several seconds, had been wasted as seatbelt pre-tensioners and airbags were only triggered when the impact occurred.

PRE-SAFE gains advance warning of an impending collision through communication between active and passive safety systems. It is linked to the ABS brakes, emergency braking assistance and electronic stability programmes (ESP), whose sensors identify critical driving manoeuvres.

If the Brake Assist system is activated, PRE-SAFE is also triggered, with the seatbelt tensioner reducing slack within 120 milliseconds, reducing forward movement of occupants by six inches.

It also corrects the position of the front passenger seat if, for example, it has been moved too far forwards or backwards, or the angle of the cushion can be adjusted.

Using the existing electric motors for the seat adjustment, the seat can be moved forwards or backwards at the rate of almost one inch per second, while the backrest can be moved at 3.5 degrees per second.

Data provided by the ESP system can activate PRE-SAFE during a skid. Seatbelt tensioners restrict sideways movement of occupants, correct passenger seat positions (including electrically-adjustable rear seats where specified) and close the sunroof. In situations where the collision is avoided, the seatbelt tensioners revert to their original position.

Mercedes-Benz says that although there are currently no plans to extend PRE-SAFE to other models, it is likely to happen in the future.

Pre-crash safety systems are not exclusive to the premium sector, with a 10-year development programme by Toyota (see below) resulting in potential application in the coming months. Toyota's pre-crash safety system comprises three core elements: the pre-crash sensor – a millimetre-wave radar that detects vehicles and obstacles ahead, seatbelts that retract as soon as a collision is identified and pre-crash braking assistance that increases braking pressure as soon as the driver begins to depress the brake pedal.

The radar provides object recognition, even in bad weather or darkness. It feeds information to a control unit equipped with software that determines whether an impact is about to take place, based on the course and speed of the vehicle, driver input in steering, throttle and braking, and the position, speed and course of any vehicles or obstacles ahead.

Like PRE-SAFE, if an impact is judged to be inevitable, the seatbelt retracts and, as soon as the driver begins to apply the brakes, pre-crash brake assist is activated.

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Analysis of about 9,000 annual traffic fatalities in Japan revealed that if pre-crash safety had been fitted to all vehicles, 1% of victims (90 people) might have survived.

Pre-crash safety could find its way into a Toyota production vehicle early this year, but no timetable has been set for its introduction in models for the UK market.

Mazda has also begun road trials of an advanced safety vehicle based on its MPV.

It is equipped with adaptive cruise control but unlike some production cars the electronics will control the brakes to bring the car to a complete stop if necessary.

Headlamps use advanced technology to vary the intensity of the beam according to driving conditions and steering angle. The spread of the beam is increased to improve visibility and recognition of traffic signs and pedestrians.

The Mazda is also fitted with a pedestrian warning system.

It judges the degree of danger based on the distance between the vehicle and an object in front measured by radar, and the vehicle's speed and braking status. The system then decides the level of danger and gives appropriate warning.

Rear-end collision risks are detected in advance by radar and the seatbelts are wound up by a motor to pull passengers back into the seat, reducing the distance between the passenger's head and the head restraint.

The new technology is no substitute for a robust risk management policy and proper driver training but, with vehicles also keeping an eye on the road and their occupants, the chance of serious accidents can only reduce and that has to be good news for all road users.

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