01-15-2018, 05:16 PM
There's one in Newport, in Wales. YouTube educator Tom Scott covers in an episode of his excellent series "Things You Might Not Know" the reasons why it's useful. In short:
Tides (at low tide a ferry won't be anywhere near the bank)
Low riverbanks (For taller ships, you'd need to build the bridge high above the riverbanks to get it high above the river. This means cost, and extending the bridge far beyond either bank.)
Age (Now, we could build tunnels. Or we could divert the motorway a few km in either direction to a better crossing location. A few km was a bigger deal back when these were built and cars weren't as fast or prevalent.)
Deep, fast, currents (Any bridge would require in-river supports. Things large ships could crash into.)
I recommend "Things You Might Not Know" to anyone who appreciates interesting things. Of particular interest to this crowd might be the episodes on The Falkirk Wheel or perhaps the one on Ascensore Castello d'Albertis-Montegalletto
Tides (at low tide a ferry won't be anywhere near the bank)
Low riverbanks (For taller ships, you'd need to build the bridge high above the riverbanks to get it high above the river. This means cost, and extending the bridge far beyond either bank.)
Age (Now, we could build tunnels. Or we could divert the motorway a few km in either direction to a better crossing location. A few km was a bigger deal back when these were built and cars weren't as fast or prevalent.)
Deep, fast, currents (Any bridge would require in-river supports. Things large ships could crash into.)
I recommend "Things You Might Not Know" to anyone who appreciates interesting things. Of particular interest to this crowd might be the episodes on The Falkirk Wheel or perhaps the one on Ascensore Castello d'Albertis-Montegalletto