Sammendrag
This report deals with the driving characteristics of trailers up to 3500 kg intended for passenger cars and vans in category B and BE drivers licenses. The aim is to address the various challenges that arise when cars, with advanced driver support systems, use trailers that are only have mechanical devices for braking, suspension and heading stability. The research project has been funded by Regionalt Forskningsfond Midt-Norge, Fylkets Trafikksikkehetsutvalg Trøndelag, and the Nord University, Handelshøgskolen Trafikkfaglige studier. Through the use of practical tests on a track, surveys, literature searches and interviews and dialogue meetings, an attempt was made to investigate how cargo trailers are affected by forces that can occur while driving on the road, as well as how cars with different types of electronic driver support systems are affected by trailers in different situations. Furthermore, it has been a goal to investigate how to ensure that drivers receive proper training in driving with trailers, and if our collected data can be used in developing VR simulation for use in training contexts as a contribution to more traffic-safe use of trailer. The laws according to these vehicles have been investigated, to find if they are suitable for road safety.
Findings show that many dealers of different types of car brands could not answer whether their cars had driver support systems that were also intended to handle trailers. Furthermore, it was discovered that statistics related accidents involving trailers are not specified.
The manufacturers of the trailers point out that they must adhere to strict regulations regarding their trailer chassis, brakes and towing, but also state that regarding equipment for carrying the load it is mostly regulated by the individual manufacturer. Tests carried out on the track with advanced measuring equipment show that the different trailers have different properties. Although some trailers have been found to affect the car more than others, it is not possible to claim that one type of construction affects the car and trailer more than others on a general basis.
The study's most important finding is that trailers that have underlying wheels with load up to maximum payload overturn at speeds well below the car's limit value. In the tests on the track, the trailer overturned at 62-65 km/h in a maneuver the car alone effortlessly makes in 75-80 km/h. This is a dramatic difference, especially as this happens with a trailer that does not require additional training to drive. For this category of trailers, consideration should be given to whether special training should be required as it is for heavier trailers, or whether specific structural requirements should be set for the trailers themselves to avoid overturning. Finding the exact causal relationships and exact limit values for the various dynamic characteristics of the trailers and of the car and trailer together will require more specific testing and research, which is strongly recommended based on this report.
From a legal point of view, motor vehicles with an attached trailer has greater danger potential than motor vehicles without a trailer. Hence there is a stricter requirement for care when driving with an attached trailer. Case law shows that the threshold for the criminal negligence of using a trailer is very low. In other words, the driver must be particularly vigilant, considerate and cautious when towing a trailer.
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