Geektastic: A further infrastructure example is commonly found in France: when they build a road bridge you will often see that the bridge is built to accommodate 2 lanes in each direction even when the road it serves is a single lane in each. This is so that in due course when traffic flows require converting that road to a dual carriageway, they do not have to tear down and rebuild an expensive bridge!
I think there's a lot of merit in this idea but it also needs to be balanced by how soon the extra pre built infrastructure will be needed and the lifespan of said infrastructure. How often would the extra spend be wasted?
Tearing down to expand dosen't always occur. They very successfully added extra lanes onto the Pukete Bridge here in Hamilton without tearing down the bridge first