[stephenr]

I thought you must surely have meant `2'` vs `6'` (i.e. feet) and simply used the wrong symbol.

I don't really understand how a 2" deep nano trench is meant to last any serious amount of time (compared to a regular conduit fully buried under the road), given how asphalt roads (particularly in a city where there is a fixed-height curb, and resurfacing works will regularly be ripping up a layer of the asphalt to be replaced.

[WorldMaker]

It fails basic civil engineering on so many levels. Imagine doing that in a city with an active frost line well below 2". How many pothole-related outages would you expect to obviously experience if you were to try such an experiment?

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

[throwaway2037]

Is cold weather bad for fiber? I'm confused by this post.

    It fails basic civil engineering on so many levels.

This is classic HN armchair engineering. I'm sure Google didn't put any thought into their physical rollout.

[stephenr]

> I'm sure Google didn't put any thought into their physical rollout.

From the article:

> “If anyone understood road technology or tire technology, [they] would know it’s going to be a problem,” said Jim Hayes, president of the Fiber Optics Association and a decades-long veteran of the industry.

> “They bid out the work to replace the sealant with asphalt,” Simrall said. But before the work started, Google Fiber saw customers lose service when the process of repaving roads damaged fiber lines. “So they shifted their attention to addressing that,” she said.

Apparently, they did not in fact put any thought into it, besides "how can we cut costs".

[js2]

The freeze/thaw cycle causes things to work their way out of the ground, so buried things you want to stay put need to go below the freeze line.

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

[WorldMaker]

With the benefits of hindsight, no it didn't look Google put any thought into their physical rollout. They had years of good planning with a rollout plan (electrical poles) with lots of city buy in that they tossed at the literal last minute to "move fast" (the rollout they did do was slower than the original plan, lol) and "break things" (city streets), with much less city buy-in and a lot fewer civil engineers even looking at the revised plan. There's certainly a lot of questions about how many civil engineers Google actually employed that would have ethically signed off on the revised plan, with the possible excuse that they were Californian or Texan engineers with less experience in the weather of rest of the country. (This is why local experience tends to matter for real Civil Engineering firms. The big ones still want small offices in as many cities as possible with as local as possible engineers around that know their area for projects in their area.)

> Is cold weather bad for fiber?

Both the Frost Line wikipedia page I included and the Frost Heaving page that has been also posted paint a picture, but if you really want a lay description, here's a rough one:

The frost line is about how far down groundwater seeps into the soil (and even most types of asphalt) and generally remains there in some proportion throughout the year. One way to think of it is that the ground can be considered some form of "moist" at and above that line at just about all times of year. That hugely comes into play in cold weather which is why it is called the "frost line": water expands as it freezes, it takes up more space in the ground and in the asphalt. This expansions causes "frost heaving", the expansion of cold water causes things in the ground to sometimes not stay in the ground, chunks of asphalt don't stay concreted to the rest of the road (potholes), etc.

So the frost line is something of the line of "if you want a thing to stay buried, you must bury at least this below the frost line". That includes buildings as the frost line even determines some of the safety requirements for the foundations of buildings as they too can get frost heaved out of the ground in worst cases.

There's never a case where "nano-trenching" 2" into roads makes sense when 2" (or more) potholes are common naturally in cold weather. That's why civil engineers have used terms like "frost line" for centuries at this point. Just one pothole and the wire is at the very least exposed to the elements. At that point it is running through the middle of a pothole in the middle of a road so you should be able to guess what the most likely next outcome is, even in the best case that the wire survived the frost heaving.

(This is also before you add in the fact that burying under 2" of asphalt wasn't even their first attempt, but their second. Their first attempt was burying under 2" of epoxy or as more commonly named: glue. Their terrible epoxy melted in warm weather, creating warm weather potholes in the streets. Their terrible epoxy mixed worse with water and turned city streets into nothing but potholes in the cold weather.)

On its own, it's really hard to give Google any credit for forethought in their rollout because potholes in cold weather is such common sense, no shit, Sherlock it shouldn't have ever needed to be said up front.

That said, I'm sure it was said up front a lot that the city was "untrenchable". Most of the city, especially the urban core and several major neighborhoods, isn't a good candidate for any sort of trenching. Not just because the city has a low frost line (which it does), but also because the city is in the middle of what is referred to as "karst country". The city is on top of giant limestone deposits which are full of caves both man-made and natural. Dig too deep (which is not far below the frost line of the city) in many neighborhoods and you risk sinkholes and cave-ins and worse.

A civil engineer I'm not allowed to name because they were under NDA at the time and Google would sue them said to me once, and I paraphrase because there was a lot more cursing and foul language over beers "What part of untrenchable did those idiots not understand?"

[js2]

How do those untrenchable locations receive water and sewer? If water and sewer can be installed underground, why not fiber?

Isn't it just that traditional trenching would have been too expensive for Google to justify?

Google apparently didn't even want to spend the expense running it on utility poles, which frankly, I would naively think would be the cheapest option.

[WorldMaker]

> How do those untrenchable locations receive water and sewer? If water and sewer can be installed underground, why not fiber?

I am not a civil engineer, I only drink with them occasionally. I'd imagine there are some big differences between heavy pipes in various states of liquid internal pressure above the frost line and bundles of relatively lightweight cables, but I'm very much just guessing at that point. I do know that there are lot of processes in place to plan that sort of work and it can get very expensive. (I see some of my sewer bills. Though the city is also unfortunately in the middle of several huge combined-sewer-overflow rework projects.) So yes, cost would be a big factor, but I think the cost is partly such a big factor because of the physics of all of it and planning it in safe ways that don't damage the neighborhoods, at least that is my very lay understanding of it.

> Google apparently didn't even want to spend the expense running it on utility poles, which frankly, I would naively think would be the cheapest option.

That's the part that still most boggles my mind. That was by far the cheapest option than a bizarre R&D for "exotic new epoxies" and all the money spent in digging up and then replacing asphalt. At one point (after the epoxies failed) they pawned a lot of that cost of the replacement part off on the city by picking up the city's normal pothole/repavement maintenance plans and dredging their nano-trenches just before, which was "smart" cost cutting in an evil sort of way.

Not only was using the utility poles the cheapest option, it was the planned option for years. It was the option that the city spent millions of tax dollars litigating for free for Google's part to make it even cheaper, about as cheap as it could possibly legally be. Google didn't pay a dime for those legal challenges. The city won those court cases! They had the go ahead to Google to do "just about whatever they wanted" with city utility poles and Google decided to do "Plan B" at the 11th hour after the go ahead.

I guess some impatience comes in to play, because it did take years to get that "go ahead" and I guess Google thought a "productive" use of those years was to experiment with silly glues and then they accidentally sunk cost themselves with R&D money into going with that Incompetent Plan B even though Plan A was still on the table and extremely viable and cheap. It's still hard not to also call that impatience its own form of incompetence, though, because that R&D didn't seem to take much reality into account. (Glues? In streets? Streets that experience weather? Streets that Americans drive heavy cars, trucks, and SUVs on? Really? They wasted how much money on that?)

[kalleboo]

Supposedly while resurfacing, you're supposed to be able to just take the fiber out https://www.youtube.com/watch?v=fvzGqA2b0aw

[cozzyd]

Why don't they fix the choreography, so the dwarves no longer tread on it?