I spent a good chunk of this morning talking and thinking about underground building details that most people (unless you're in the industry) would never think to consider. This is not a criticism on most people. I mean, I don't know how iPhones are made. I just use and enjoy them. But when it comes to buildings, I'm paid to ask questions and understand how things work.

There's a lot of risk in the ground.

You have to think about things like bearing capacity, environmental contamination (usually), hydrostatic pressure and, generally, how you're going to manage water, particularly if you have a high groundwater table. Usually this last one is about making sure you're keeping the water out. A pretty important detail both below and above grade.

So when I came home tonight and saw the below tweet, I felt obligated to write about it.

If you read the reply from NYC's Metropolitan Transportation Authority, you'll see that this is them testing something they call a "flex gate." It is a flood barrier that allows them to seal off subway entrances in the case of a storm surge and they run these tests (shown above) for 4 hours at a time to make sure they're installed property. This one was.

Managing water is a big part of city building. New York City, Miami, Venice, and countless others know this all too well right now.

Venice has been keeping flood records for 150 years, though it is generally understood that the city has been regularly flooding since the very beginning. It usually happens between the fall and the spring and the earliest record is believed to be from the 6th century.

This past week, Venice saw its acqua alta (or high water) peak at 187cm (6'2") above its normal level. This is the second highest number on record and is just below its 1966 peak. At these numbers, about 80% of the historic center is underwater. Here is a chart from the WSJ explaining that:

Venice has been working on a flood management project called MOSE since the 1980s. The name is an acronym, but there's a deliberate biblical reference here. Remember when Moses parted the red sea?

The project has been mired in engineering delays and corruption scandals, and so it's not yet operational. If it were, it would have, in theory, protected the city this past week. 2022 is the anticipated completion date, but I don't know if that's realistic or not.

The system consists of 78 mobile gates that fill with water and sit flat on the seabed when the tide is low. When a high tide is predicted, the gates are then to be pumped with air so that they rise (hinged on one side) and close off the three inlets that connect the Venetian Lagoon to the Adriatic Sea.

As I was reading about this project and everything else that has been going on in Venice this past week, I became curious about how exactly the Dutch have been managing to hold back the sea. I mean, a big chunk of the Netherlands sits below sea level.

If you're also curious, here's a video that explains how they do it.

I spent a good chunk of this morning talking and thinking about underground building details that most people (unless you're in the industry) would never think to consider. This is not a criticism on most people. I mean, I don't know how iPhones are made. I just use and enjoy them. But when it comes to buildings, I'm paid to ask questions and understand how things work.

There's a lot of risk in the ground.

You have to think about things like bearing capacity, environmental contamination (usually), hydrostatic pressure and, generally, how you're going to manage water, particularly if you have a high groundwater table. Usually this last one is about making sure you're keeping the water out. A pretty important detail both below and above grade.

So when I came home tonight and saw the below tweet, I felt obligated to write about it.

If you read the reply from NYC's Metropolitan Transportation Authority, you'll see that this is them testing something they call a "flex gate." It is a flood barrier that allows them to seal off subway entrances in the case of a storm surge and they run these tests (shown above) for 4 hours at a time to make sure they're installed property. This one was.

Managing water is a big part of city building. New York City, Miami, Venice, and countless others know this all too well right now.

Venice has been keeping flood records for 150 years, though it is generally understood that the city has been regularly flooding since the very beginning. It usually happens between the fall and the spring and the earliest record is believed to be from the 6th century.

This past week, Venice saw its acqua alta (or high water) peak at 187cm (6'2") above its normal level. This is the second highest number on record and is just below its 1966 peak. At these numbers, about 80% of the historic center is underwater. Here is a chart from the WSJ explaining that:

Venice has been working on a flood management project called MOSE since the 1980s. The name is an acronym, but there's a deliberate biblical reference here. Remember when Moses parted the red sea?

The project has been mired in engineering delays and corruption scandals, and so it's not yet operational. If it were, it would have, in theory, protected the city this past week. 2022 is the anticipated completion date, but I don't know if that's realistic or not.

The system consists of 78 mobile gates that fill with water and sit flat on the seabed when the tide is low. When a high tide is predicted, the gates are then to be pumped with air so that they rise (hinged on one side) and close off the three inlets that connect the Venetian Lagoon to the Adriatic Sea.

As I was reading about this project and everything else that has been going on in Venice this past week, I became curious about how exactly the Dutch have been managing to hold back the sea. I mean, a big chunk of the Netherlands sits below sea level.

If you're also curious, here's a video that explains how they do it.