Most road accidents happen because of driver error, but some
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are caused by careless maintenance. Whatever the cause, the emergency services are left to pick up the pieces—and to work out what went wrong.
Day after day the emergency services are called upon to deal with the result of a moment's loss of concentration or, worse, the criminal negligence of those who have failed to maintain their vehicles. Police officers are exposed to a greater degree of human misery than most and neither training nor experience can really prepare people for the numbing exposure to sudden death.
Following the M2 coach crash in November 1993, all those who were in any way involved were offered professional counselling. Nonetheless many of them are still suffering the after-effects.
COUNSELLING
PC Stephen Ridley of Kent Police was the first officer on the scene. "I still get pains in my chest when I pass that stretch of the motorway," he says. "I am lucky in that I received professional counselling the same day but in spite of that I get flashbacks and occasionally have difficulty sleeping."
Not all accidents are that stressful but establishing the causes can still demand high levels of expertise. In April last year an accident investigator was called to an incident where a petrol tanker had crossed the dual carriageway and collided with a private car before demolishing the wall of a bridge over a railway line.The cause of the accident was eventually found to be loose nuts on the axle U-bolts which had been removed by a contracted garage the previous day to allow a new road spring to be fitted. During the course of the journey on the day of the accident the nuts had fallen off, allowing the axle on the offside to slide back and cause the tanker to veer sharply to the right. Traces of road dirt subsequently found in the thread of the U-bolt proved that the nuts had been missing for many miles prior to the accident, a fact initially denied by the repair company.
The tanker owner was unaware of the faulty maintenance and was exonerated of any blame.
CORNERING
Two years ago officers in west London were called to examine a Magirus-Deutz articulated towing a monocoque trailer which had toppled while cornering. No-one was seriously hurt but investigators found that the vehicle had only just been returned to service after toppling over.
They noticed that all the linkages were badly worn and there were a network of cracks on the side. The owner-driver admitted that he had converted the trailer making it a metre taller and 1.5 metres longer. The extra laden weight had caused a lack of stability which the owner had tried to solve by welding large angle brackets to the fifth wheel. These had fractured under the strain but the owner fully intended to use the vehicle again.
In complicated cases, particularly where LGVs are involved, the accident investigator will bring in a forensic scientist and a vehicle inspector—but sometimes even their combined expertise cannot supply all the answers. One such case occurred in the autumn of 1987. A 200kg wheel from a Crane-Fruehauf tri-axle semi trailer on the M25 came off, crossed the central reservation and hit the roof of a car, killing the driver.
The axle and wheel were sent to the forensic science laboratory for examination which showed a sustained period of direct contact between the wheel drum and the brake shoe had caused a massive heat build up. Friction, under load, had also worn away the wheel bearing inner races causing them to disintegrate and partly melt.
There was no suggestion of any manufacturing fault and the laboratory was unable to establish which bearing had initially failed, or why, so there the matter had to rest.
"We have to carry out these detailed examinations for the sake of all those who are involved in an accident," says PC Paul Croft of the Metropolitan Police. "Sometimes what appears to be a clear case of dangerous driving is the result of a technical fault on the vehicle. More usually it is the other way round. A driver will allege that his brakes failed or that something else went wrong. We have to be able, if at all possible, to satisfy the Coroner or the Magistrate as to the exact cause of the accident."
According to the men and women of the Accident Investigation Units, the vast majority of accidents are caused by driver error, and some of those errors are caused by long hours behind the wheel. Fortunately accidents caused by faulty maintenance are rare, but they are not unknown. Last September six people died at Sowerby Bridge because a truck had defective brakes—clearly the implications of less than perfect maintenance can be very serious.
CI by Patrick Hook.