There are also other factors. Imagine you gave a 500yo bridge that is low maintenance and has stood the test of time and all those nice things, but you can't ca

There are also other factors. Imagine you gave a 500yo bridge that is low maintenance and has stood the test of time and all those nice things, but you can't carry the weight of modern vehicles, or if it's not wide enough for modern vehicles etc etc One of the many tradeoffs in design is how much do you want to spend in preparing for anticipated future demands. Striking example in my home town of Zagreb. Communist city planners at the time designed new neighbourhood with plenty of parking space because one day productivity advancements will give every family a car to own and they need to have a place to park it! A few decades later you couldnt find a parking space anywhere because every family had two or three cars!