I find it surprising that a bunch of people who apparently have no real concept of what real engineering is are commenting on this. Bridge overpasses are not all essentially copies of what was done before. Yes, you are using a similar structure, but each location presents particular challenges, be they in maintenance of traffic operations, construction sequencing, geotechnical constraints, location issues, etc. Generally speaking, concrete structures are very repetitive utilizing similar beam sections in many structures. Steel structures, on the other hand, are completely different and there is an infinite combination of plate sizes that would yield adequate results. I’m not even going to talk about post-tensioned, cable-stayed, truss, or arch structures.
Not only that, but you are all referring to one specific subset of engineering, namely structures. You are completely ignoring chemical, electrical, industrial, mechanical, aerospace, or geotechnical engineering, not to mention the remaining branches of civil engineering (hydraulics, traffic, transportation, etc). It is capricious to state that engineering is repeating previously conceptualized designs to fit a current situation. While that may be SOMEWHAT accurate in STRUCTURAL engineering, it is completely untrue of say electrical or mechanical engineering. Do you really think that the inventors of the Synergy Energy Drive from Toyota were copycatting? Building on a previously existing design, yes, but not copying some engine that worked somewhere else and putting it into a new frame. And while they may be working in God’s constraints, they are also trying to further understand those constraints (meaning, those constraints are NOT fully known or understood) in such a manner as to increase the machine’s efficiency without a loss of power. That is but one example.
Can a civil engineer say that More than half of everything I know will be obsolete in ten years? HECK YES I can (maybe not completely obsolete, but what they do now will NOT be what is done in 50 years). I’m pretty sure that if John Roebling miraculously came back to life today and wanted to design the Brooklyn Bridge, it wouldn’t happen. Granted, that WAS 100 years ago, not 50. The basic fundamentals of civil engineering, i.e. mechanics of materials, will not and have not changed. However, design methodology has changed, software and calculators have and will continue to be developed, and our beloved codes are constantly being updated and rewritten. Case in point, strut-and-tie method for shear and torsion design in concrete. That didn’t even exist 50 years ago. Not to mention changes in technology (prestressed concrete was first used in 1937, post-tensioned concrete in the US has only been around for 40 years) and changes and advances in materials and material properties (steel has only been used for bridges for around 150 years - prior to that it was cast iron, concrete strengths used to top out around 4000 psi and we can now get over 10000 psi and composite reinforced polymers are being invented and researched as a new structural material). Anyway, point is, things change in civil engineering, too.