In two crash tests, the hypothesis that the personal equipment which the police carry on their uniform might affect the function of the seat belt in a collision was put to the test. To sum up, it can be said that nothing was found to indicate that the flak jacket has a significant negative effect on the function of the belt. It was further found that the items of equipment carried on the equipment belt around the waist do not themselves entail any significant increase in risk, even though it cannot obviously be excluded that even small but sharp objects can cause local but severe injuries in accidents. More generally, it is found that, in a purely physical sense, the size of the uniform belt displaces the lap portion of the seat belt from its correct position around the hips of the wearer, which gives rise to an evident risk of submarining. At present, a normal belt tensioner is not able to recover all the slack which the equipment induces.

Many professional groups use a vehicle as an essential part of their work. The vehicle is not only a means of transport, it is a tool and also, to a large extent, a workplace.

Vehicles that are used as part of people’s work, or the people who use the vehicle, are often equipped with tools and other equipment which may come into conflict with the damage alleviating system of the vehicle. The police, ambulance service and rescue service have many such vehicles with special equipment, but it is probable that guards, veterinary surgeons and district nurses also often have vehicles and equipment which may conflict with the requirement for vehicle safety in a crash.

Risks probably also exist for postmen in post vehicles, tradesmen in specially constructed vehicles or with a lot of tools in their tool belts, and perhaps also for the drivers of vehicles for the transport of valuables, vehicles which are probably neither easily deformable in a collision nor particularly easy for the Rescue Service to work on in the event of a rescue attendance after a traffic accident.

We have become accustomed to modern vehicles being fitted with all kinds of safety equipment. As far as direct personal protection in a collision is concerned, it is the seat belt and air bags that first come to mind. Different forms of load anchorage systems may also be said to be part of direct personal protection. What is more concealed but equally important from the standpoint of collision protection are details such as the design of the seat, the design of the neck/head restraint and e.g. the geometry of the seat belt and the presence of belt tensioners and their function. The seat usually also has submarining protection that cannot be seen by the naked eye.

A modern car is subjected to crash tests and receives approval, with only ”ordinary” dummies placed in the car seat, belted up properly and with air bags etc activated according to all the rules. An alternative, professional use of the vehicle, in relation to the crash safety aspects of the clothing or other equipment details of the passengers, is probably never published.

Jan Wenäll, research engineer VTI, +46 70 518 43 73
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