What is a road train

You probably already heard about road trains if you are planning go to Australia. But as always it is better to see once then thousand times to read about it.
But lets start from other countries before heading to Australia.
In the United States, trucks are limited to two trailers (the length limit is 19.2m (63 ft) end to end) on public roads. In less populous states it is allowed three trailers.
In Finland, Sweden, Germany, the Netherlands, Denmark and some selected roads in Norway trucks with trailers are allowed to be 25.25 m (82.8 ft) long. Elsewhere in the European Union, the limit is 18.75 m (61.5 ft).
In Canada road trains (or Long Combination Vehicles) may be up to 38 m (125 ft).
But largest and heaviest road-legal vehicles in the world are in Australia.
Road train. Australia
53.5 metres (175.5ft). That’s the maximum allowable length of road train on public roads. How big it is? For example the regular bus is about 12-13 meters (40-43ft) long. So just imagine 4 buses standing in one lane to get impression how long road trains in Australia are. But on private mines there are even longer road trains.