To optimise the vehicle we have to use a sequential unconstrained minimisation technique and we have the parameter of the length of the vehicle, of the mass, which refers exactly to the length of the vehicle, and we have obtained such result. We can see here a coach with an axle load of 13 ton. The coach weights 450 kg per seat and the train carry almost 700 passengers per 100 m. If we shorten the coach, we can get a coach with almost the same load, but the coach is able to weight only 300 kg per seat, and a train 100 m. long is able to carry 925 passengers. This is due to the fact that if we decrease the length of the coach we are able to have a cross width, which is wider and so, a higher number of sitting passengers can actually be carried by the vehicle.

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