So one thing that fascinates me as a "lighting guy", when it comes to road construction is poles. There are a lot of different types of poles used for road infrastructure, including lighting but also traffic lights and signage.
An interesting thing is that the types of poles used are very regional by nature, largely dependent on the local supply chains.
Ontario and Quebec for instance use a lot of concrete poles, for one reason, and one reason only - the only two concrete pole manufacturers are located in Ontario (one in the GTA, and one in metro Ottawa. Concrete poles are incredibly heavy, so it just doesn't make any economic sense to use them any further out since the cost of freight starts going up dramatically the further out you go.
Outside of these two provinces you will almost never see concrete poles - the freight is simply too expensive. (the reason these two technologies are made here is likely due to the amount of salt thrown on our streets during the winter, but I don't know this for sure)
Everywhere else in Canada uses mostly steel poles - basically what they do is they take a steel plate, and bend it into either circle, square, hexagon, octagon etc. You'll also see cast steel for downtown areas, but this is more expensive. Spun aluminum poles also get used in a lot of areas.
However for freeways, the king across the country - even Ontario and Quebec - is galvanized steel. This is the same as a regular steel pole, except they dip it in a hot zinc bath which adds a protective coating to the outside layer of the pole, increasing its corrosion resistance exponentially.
Any time you see one of these, it is always galvanized steel. There is simply no better alternative. They can be shipped in 30ft sections and assembled on site. The total pole length can be up to 200ft (although taller than 100ft is rare for highways). They pole is also hollow, which makes it easy to run cables through, and as a result makes it possible to use lowering devices for the lights (rather than having to use a boom to access it). Steel is also incredibly strong.
The part I find most fascinating is that this massive structure, which can weigh over 10,000 lbs is only supported by a few anchor bolts submerged in concrete. Steel and concrete is incredibly strong.
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