Anyone who still thinks driving on the motorway is somehow safer than in the city (seen as how you’re surrounded by fewer cars), needs to take into account the speed limit difference.
The faster you drive, the more focused you have to be, otherwise you might just get caught off guard by somebody all of a sudden slowing down ahead of you, which is precisely what happened here, with devastating results.
Starting with the semi driver, they were clearly following the caravan a little too close for comfort, which actually made this crash rather inevitable, at least in these circumstances.
Then there’s the silver car ahead of the caravan, which is a little difficult to spot at first. There’s a possibility that the silver car may have been brake checking the black vehicle towing the caravan, although at that point, slowing down to a crawl for whatever reason other than a catastrophic mechanical failure is pretty inexcusable.
Either way, all these factors coming together is what led to that caravan getting obliterated by the semi. Thankfully there didn’t seem to be anybody inside – it is illegal to ride in a towed caravan.
To make matters worse, other vehicles were affected too, like that blue VW van that almost crashed into the concrete divider.