Project deliverable for basic mechanics

Imagine that you are a mechanical engineer working for a road construction company. Your manager have given you the task of designing a steel truss bridge in one of the highways to be constructed by the company. You have been given the freedom to design the bridge in anyway like provided that the bridge is strong enough to support a truck weighs 225 kN and that cost is kept as low as possible. – I have to  create 3 designs for the truss bridge using West Point bridge designer software  and  also I’ve to compare between them (economically, Factor of safety)- also do hand calculations (using the method of section for the selected members)-finally the desicion making part ( I have to choose the best one according to the software and hand calculations that I have done above)