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Drivers Perception of Secondary Braking Systems

Funding Organisation: Department for Transport


Partial brake failure of vehicles is a rare occurrence and total brake failure is even more unlikely. Due to the "spongy" or "hard" pedal feel that accompanies most partial brake failures, many drivers perceive they have suffered total brake failure. In reality, they often retain a fully operational secondary braking system and drivers can still achieve around 50% of the maximum braking normally available to them.

The braking behaviour of typical drivers was assessed on the proving ground and in the LADS. 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.

The project concluded with legislation recommendations to DfT regarding potential driver information and vehicle modification.