Last week a Lincolnshire bus driver was sentenced to five years imprisonment for causing death by dangerous driving. It had been a busy bank holiday weekend in the seaside town of Ingoldmells when shortly after 5pm on Sunday the 11th of April 2004 a bus pulled away from the bus stop to head up Sea Lane. Shortly after starting to pull away the bus suddenly accelerated rapidly and continued to do so as it drove over a pedestrian crossing, narrowly missing several people who were on the crossing. Shortly after this it swerved to the left to avoid a stationary car and mounted the pavement. Five people from Nottingham and Leicester, including a small child, who were on the pavement at the time were tragically killed when the bus collided with them. The bus finally came to halt some distance further down the road.

For anybody who has not had direct experience of such a horrendous event it is impossible to truly understand the horror and grief felt by the families of those who were killed on that day.

Unfortunately the English criminal justice system failed to help the families understand what had lead to these deaths, something that may help them in their grief. Nor, importantly, did it do what it should have done to help prevent further accidents of this type. This is because the judge ruled that the scientific explanation of the cause of the accident was inadmissible in court and could not be put to a jury.

So what is this scientific explanation for these ‘unintended acceleration accidents’, which have been known of in the fields of road safety and human psychology since at least the 1970s? The first point to make is that they are not due to a fault with the vehicle. The reason the vehicle initially accelerates very fast is that the driver, needing to make a rapid application of the foot brake, actually presses the accelerator pdal instead. This is due to a foot aiming bias at the time the foot movement is initiated which in turn can be caused by upper body twist such as looking over the shoulder to operate hand controls, check the road is clear when pulling out or attending to passengers who have boarded the bus. The accelerator and brake pedals in buses can be very similar in shape, height and angle so the only way of distinguishing them is by their position and the foot aiming bias effectively eliminates this cue.

When the driver then presses down hard on the (accelerator) pedal, believing he is applying the brakes the bus suddenly and unexpectedly accelerates forward. This is startling to the driver, and the immediate risks of collision with other vehicles and pedestrians can evoke the panic state of ‘hypervigilance’. In this state the individual’s focus of attention is narrowed and his ability to process information and make decisions can be disrupted. The driver’s attention may be so focussed on the scene through the windscreen and steering the vehicle to avoid collisions that he is unable to detect his foot is on the wrong pedal or to plan and undertake any other action to bring the vehicle to a halt in the time available. Indeed drivers typically continue to insist, when interviewed after the accident, that their foot was on the brake pedal and that the vehicle simply ‘surged’.

There is only space here for this very brief summary of the cause of such accidents (a fuller account is given by the paper by Schmidt, who developed the explanation). It is however based on a review of extensive laboratory and real life research involving typical people, and scientific understanding of the manner in which the brain controls limb movement. The implications of this explanation are that, in the right circumstances, anybody driving an automatic vehicle, such as a bus, could experience this type of accident. It does not imply any failure on the part of the driver. It should also be noted that no other scientific explanation of these accidents has been proposed.

However, in English law, there are only a finite set of defences to the charge of causing death by dangerous driving and in this case the judge ruled that this explanation did not fall within any of them and therefore could not be put to a jury. At this point the driver had not option but to plead guilty. The judges’ opinion, rather than a jury, informed by objective scientific evidence, had therefore decided this case.

In passing sentence the judge stated “It is difficult to imagine a more serious single example of your dangerous driving…..” I would suggest the judge has a look at some of the many previous accidents I have had to investigate, including the similar fatal case in Sunderland in 1998.

Finding the driver wholly and solely guilty severely reduces the incentive for measures to be found to prevent future accidents of this type (e.g. modifications to vehicles, driver training) and does nothing to improve public safety.

The severe penalty imposed by the judge on the driver will cannot deter other drivers from committing this crime: they do not do it deliberately or due to lack of care, or under the influence of fatigue, drink or drugs etc.

So, other than reacting with pious retribution, just how has the justice system served the people in this case? I sit here with a feeling of foreboding, as I did after the Sunderland accident, waiting to hear of the next fatal unintended acceleration accident, which the criminal justice system could have helped avoid. Meanwhile a bus driver, guilty of no more than being human, must endure a five-year prison sentence on top of the lifetime of anguish from the horror he experienced on that dreadful day.





Reference
Schmidt, R. A. Unintended acceleration: Human performance considerations. In Peacock B and Karwowski W (Eds) Automotive Ergonomics. Taylor and Francis 1993.