The "trains" we call "Road Trains" they have a prime mover and 3 or 4 trailers and are restricted to highways outside of cities or city regions. A B-Double typically has a Prime mover and one short trailer followed by one long trailer. This is the biggest combination allowed on city roads. Some times on the highway you'll come up behind one and it isn't obvious it's two trailer job, it's only when you pull out proper to overtake that you realize it's the big one and then you're glad you're on a Busa. I like to drop down to third or even second before I pull out even if the road ahead looks clear for some ways. They are not the sort of thing you want to linger around.
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That's a lot of real estate.