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Comment by lucb1e | Hacker News Reader

Are aqueducts common where you are from?

As someone from the Netherlands, I honestly don't understand the article. It speaks of a 'unique' project and a 'novel' approach, but the only thing that's supposed to make it so seems to be:

> Unlike other solutions for allowing vehicular traffic and waterborne traffic to pass over or under one another, engineers decided on a different approach: a water bridge.

While aqueducts are far less common than normal bridges in the Netherlands, they're a normal concept to me. Are they that uncommon? Does your country have them?

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I haven't heard of an aqueduct here in the United States capable of carrying boat traffic. I think of aqueducts here as only part of drinking water or irrigation water systems, like the California Aqueduct which brings water from Northern California to Southern California.

https://en.wikipedia.org/wiki/California_Aqueduct

I don't think of them as parts of navigable waterways!

Edit: Apparently there are some, mainly on the Erie and Chesapeake and Ohio canals.

https://en.wikipedia.org/wiki/Category:Navigable_aqueducts_i...

https://commons.wikimedia.org/wiki/Category:Canal_aqueducts_...

The Erie Canal is still operating along with some of its aqueducts, while the Chesapeake and Ohio canal has been shut down and it seems most of its aqueducts are no longer maintained or operational.

I don't think I ever knew about that. Maybe it's better-known to people who live in the vicinity of those canals?

Artificial navigable waterways are a lot more pervasive in the Netherlands than here. :-) Maybe partly because the U.S. is a lot hillier.

The Erie Canal opened in 1825, and the first railroad in the US opened in 1831. It was a bypass for a slow section of the Erie Canal. So narrow canals in the US became obsolete before many were built.

The California Aqueduct has some water bridges over the aqueduct.[1] That's to keep agricultural runoff out of the water supply.

[1] https://earth.google.com/web/@37.1548186,-121.06138975,71.78...

You do realise that an aqueduct carrying only water is carrying the same load as one carrying lots of ships? (maybe you do) The weight of the ships displaces exactly the amount of water with that weight. There is of course some water movement to deal with, and there are safety margins required, in case of accidents, etc. - perhaps that was your point, but I think it's worth pointing out, if people aren't familiar with aquaducts.

I read that once but had forgotten it until you reminded me, so thanks!

I was thinking that aqueducts for drinking and irrigation water usually wouldn't be navigable because their waterway is too small (too shallow or too narrow), or, for drinking water, is sometimes covered or enclosed.

Edit: For example, EBMUD has a major aqueduct coming from

https://en.wikipedia.org/wiki/Pardee_Dam

(https://www.ebmud.com/files/cache/f49ff54bdbea934d88a2bfee40... -- none of it navigable or even close!)

while SF Water has a major aqueduct coming from

https://en.wikipedia.org/wiki/O%27Shaughnessy_Dam_(Californi...

Both of these use enclosed pipelines and spend a significant portion of their journeys underground!

I think L.A. has something similar. Edit 2: Yep, the enormous and also totally non-navigable https://en.wikipedia.org/wiki/Los_Angeles_Aqueduct

Plenty here in the UK. Here’s the best known: https://en.wikipedia.org/wiki/Pontcysyllte_Aqueduct - the highest in the world and a UNESCO World Heritage Site.

Another in the UK is the Iron Trunk, carrying the Grand Union canal over the river Great Ouse:

https://www.nationaltransporttrust.org.uk/heritage-sites/her...

This one is just outside Milton Keynes, which might be a bit more accessible to foreign HN readers visiting the UK than the Welsh Marches.

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