Technical defects as a cause of accidents
Various international studies such as the aforementioned ETAC Study prove that technical vehicle defects are responsible for slightly more than five percent of accidents involving goods transport vehicles. We can also reckon with additional, unreported cases here as well because it is usually very difficult or even impossible to detect vehicle defects on site – in most cases, in-depth technical inspections conducted by an expert do not take place. However, the low rate is certainly also a result of the existing system of vehicle inspections involving professional roadworthiness tests conducted by expert organizations such as DEKRA and other service providers.
As is the case with cars, roadworthiness tests conducted by DEKRA in 2016 and 2017 on trucks and tractor trucks that are registered in Germany and weigh over 12 metric tons show that the rate of defects increases as the vehicles age. While under 22 percent of vehicles up to three years old are found to have defects, this figure is over 50 percent for vehicles over seven years old and over 60 percent for vehicles over 12 years old. The situation is better for trailers weighing over 12 tons, with 20 percent of trailers up to three years old presenting defects and 44 percent of trailers over 12 years old presenting defects. In terms of defective components in trucks and tractor trucks, the electrical system and lights were the components that showed the most defects by far. The reason for this is that a huge number of lights are installed in these vehicles, eventually resulting in a high number of defects with this equipment. In the case of trailers, the braking system and lighting devices were the components that suffered the most defects. As a general rule, the rate of defects increases across all components as the respective parts age – and this applies to trucks and tractor trucks as well as trailers.
A similar development can be observed with vans, as an analysis of DEKRA data from 2016 and 2017 shows. While 78.3 percent of vehicles inspected with a mileage of up to 50,000 kilometers did not present defects, this proportion decreased to 37.6 percent for vehicles with a mileage of 150,000 to 200,000 kilometers. The number of major defects in the mileage categories specified increased from 10.9 to 39.2 percent. Defects relating to the electrical system and lights were the most frequent defects in this case too, followed by the brakes and engine.
In addition to the results from DEKRA vehicle inspections, the analyses of trucks involved in accidents provide interesting insights into the defects seen in heavy-duty commercial vehicles. In terms of technical condition, there are clear differences between younger and older trucks. An analysis of the defects in commercial vehicles weighing over 3.5 metric tons found by police directly at the scene of the accident revealed that, from 2007 to 2016, approximately 41 percent of accident-related defects in Germany occurred in vehicles up to five years old. Vehicles over five years old accounted for 59 percent of accident-related defects. The fact is that police can detect defects that are noticeable from the outside directly at the scene of an accident. A detailed inspection in a workshop conducted by independent experts generally reveals many more defects. From 2006 to 2017, for example, the police classified defects with tires detected directly at the scene of an accident as the cause of accidents in 36.5 percent of cases. A detailed analysis conducted by DEKRA experts taking into account all accident-causing defects found the brakes to be the cause of accidents in 50 percent of cases. Overall, defects with tires and brakes in commercial vehicles weighing over 3.5 metric tons are the defects that most frequently cause accidents. It is a similar situation for vans weighing up to 3.5 tons. The figures underline the importance of regular maintenance and servicing as well as roadworthiness tests for vehicle safety.