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?"