Ethical issues in engineering design - 3TU.Centre for Ethics and ...

Design of a lightweight trailer
trucks or trailers in crashes. These prevention measures can be added to the
trailer structure but they can also be incorporated in the design of trailer
structure. Regulation on precautions to prevent cars from going under trucks is
being prepared in the European Union and will come into force in the next few
years. It is, however, possible to incorporate some precautions in present day
designs.
In one of the meetings the engineer/salesperson from the engineering
company mentioned a trailer (called Safeliner) built by Krone that is constructed
in a way such that cars cannot go under the trailer in a crash. In the same Krone
design the sides of the trucks are completely covered to prevent cyclists and
pedestrians from being drawn under the wheels during an accident. In the
Safeliner design, traffic safety features are incorporated in the structure and not
added at the end of the design [www.krone.de]. The customer thought that a
Safeliner would be very expensive.
The engineers in this case equated a safe trailer with a structurally reliable
trailer without paying any attention to traffic safety. This was partly due to the
customer. The customer said in an interview that he thought that traffic safety
was very relevant and that it was part of the image of the trailer. His idea was to
completely cover the sides, but this cover was not something he considered to be
part of the structure. Therefore he had not incorporated this need into the
requirements for the structure. For the customer the side covering and underrun
protection were part of the image of the trailer and something you add to the
structural design of the trailer after it has been designed. In the Safeliner the side
covering is part of the structure.
7.3.1 Structural reliability
According to Liz and Hans, a safe trailer was a structurally reliable trailer that
manoeuvres well. There are different aspects to structural reliability. The strength
of the trailer is important to prevent sudden failure of the trailer in the case of an
extreme loading. In some parts of a trailer fatigue can be a problem. The stiffness
of the floor and side panels should prevent extreme bending and deflection. The
resistance against rotation called torsional stiffness influences driving and
manoeuvre possibilities (cf. [Gere and Timoshenko, 1995, 162]).
The stiffness of the floor of the trailer was important because it should be
level for the unloading system to work and should not feel unstable when a heavy
driver walks through the empty trailer. A trailer will also not look reliable if the
floor or side panels are too flexible. The engineers called this requirement for
stability an optical requirement, the trailer should look reliable. This optical
requirement was given a value by stating in the design requirements that the
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