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cloaca maxima

When to Build Millennia Sewers

In the mid-1800s, every building in central Chicago was raised 10ft (30m). Yes, they literally used jackscrews to lift entire city blocks up one-by-one.

Chicago had to hotfix production because they built the city on the shoreline of Lake Michigan, where filth accumulated without natural drainage. They lifted the entire city after it was built so they could add sewers and prevent flooding.

For comparison, Rome's Cloaca Maxima ("Greatest Sewer") is still in-use after 2,400 years.

So why didn't Chicago just build it right the first time?

Irreversible Decisions

Some decisions are consequential and irreversible or nearly irreversible – one-way doors – and these decisions must be made methodically, carefully, slowly, with great deliberation and consultation. If you walk through and don’t like what you see on the other side, you can’t get back to where you were before. We can call these Type 1 decisions. But most decisions aren’t like that – they are changeable, reversible – they’re two-way doors. If you’ve made a suboptimal Type 2 decision, you don’t have to live with the consequences for that long. You can reopen the door and go back through. Type 2 decisions can and should be made quickly by high judgment individuals or small groups.

As organizations get larger, there seems to be a tendency to use the heavy-weight Type 1 decision-making process on most decisions, including many Type 2 decisions. The end result of this is slowness, unthoughtful risk aversion, failure to experiment sufficiently, and consequently diminished invention. We’ll have to figure out how to fight that tendency.

-- Jeff Bezos

The Cloaca Maxima didn't magically start out as the Greatest Sewer. It began as an open-air canal, then was modified and renovated and connected to the aqueducts.

The Romans probably made mistakes, but they didn't make any wrong irreversible decisions. To build something that lasts, make sure the architecture is correct where it counts.

The Chicago sewage disaster was technically reversible, but extremely expensive and painful.

Put "wiggle-room" in your architecture. Plan for repairs. Add backdoors, engine-hoods, seams, and spaces. Emergency plans are generally cheap to include in early phases of design.

Unintented vs. Unforeseen

Exxon executives knew that CO₂ emissions would harm Earth.

Exxon willfully ignored its own research. Climate change was unintended but not unforeseen.

Prophets are silenced when apocalypses seem bad for business.

But remember -- all apocalypses are opportunities for entrepeneurship. Exxon could've made billions by diversifying themselves with renewable energy. They acted against their own self-interest by ignoring their facts.

To prevent long-term disaster, solve the hard problem of aligning incentives. Build systems so that all constituents predict and prevent impending doom.

Transparency thwarts own goals. It's difficult to do stupid things when you do stupid things publicly.

Always Scale Down

There's really two ways to design things. You can either sort of start with small things and scale them up or you could start with big things and scale them down…

So suppose you want to build a system for like 10,000 people to use simultaneously. One way of doing it would be to start with the system, design it for 10 people and test it like that and scale it up 10,000. The other way would be to design it for like 100,000,000 people -- I mean do the design for that -- and then scale it down to tens of thousands. You might not get the same architecture. You might get a completely different architecture. In fact, you would get a different architecture.

And I think it's a really bad idea to start at a design for 10 or 100 things and scale it up. It's better to start with an architecture that you know will work for a few trillion things and scale it down. It will actually be less efficient when you've got your 10,000 things than when you scaled up, but you'll know that you'll be able to scale it up later. So it's good.

So rather than ask, "how do we get to five nines?", let's make it more interesting! Let's start at 9,999 nines reliability and scale it down.

-- Joe Armstrong from Systems that run forever and self-heal and scale

If you can afford it, throw a few extra zeroes on your designs.

Labor & Materials

Carefully compare lifetime, labor, and materials.

lifetime repair labor materials
asphalt 20 years moderate $ $
concrete 30 years difficult $ $$
stone 100+ years easy $$$$ $$$

Pay particular attention to labor -- 9 women can't make a baby in 1 month.

Exercise for the reader: Which is cheaper, a Nespresso machine or a percolator?

Awful Architecture

Sometimes there are no tradeoffs.

Some decisions are awful in every dimension.

Dvorak keyboards reduce finger fatigue using the same materials as QWERTY keyboards.

Juicero famously launched a high-tech product that was inferior to traditional juicers in every comparable way:

After taking apart the device, venture capitalist Ben Einstein considered the press to be "an incredibly complicated piece of engineering", but that the complexity was unnecessary and likely arose from a lack of cost constraints during the design process. A simpler and cheaper implementation, suggested Einstein, would likely have produced much the same quality of juice at a price several hundred dollars cheaper.

If you want to create lasting sewers, study sewer architecture and its impacts. What do good sewers have in common? What do bad sewers look like? What tradeoffs exist with sewage systems? Are there any promising-yet-untested sewer designs? Why do sewers go into disrepair? What societal factors prevent sewers from being made in the first place? Who truly controls the sewers?

Great architects think ahead, but don't let ambitions run amok. They anticipate irreversible changes and second-order effects. They consider all the costs -- labor and materials and maintenance and environmental impact. They always stay ahead-of-schedule and within their budget. And despite the overwhelming constraints, great architects build millennia sewers whenever and wherever they can.