Drivers' perception of secondary braking systems

It has been alleged that in accidents where vehicles have suffered "brake failure", drivers may not be making full use of the secondary braking system, believing that their vehicle's brakes have completely failed. This perception may be due to the feel of the brake pedal (longer pedal travel) or lower vehicle deceleration rate (higher pedal load) associated with these failures. The braking behaviour of typical drivers was assessed on the proving ground and a driving simulator. It was established that, although all the drivers did make use of the residual braking, most were unable to make full use of the available performance. It was also found that the conventional warning light did not improve drivers' performance once emergency braking was required. The handbook information was also of limited benefit in influencing drivers' reactions. Long-term changes in braking technology will bring about a significant improvement in secondary braking performance. However the investigation has determined that improved pre-emptive warning systems can provide an effective method of ensuring that drivers either stop the vehicle or at least check the brake system prior to a critical situation.