At the exact moment you got "hit" by this bang, you can see on the other side of the motorway a huge crane. If one of the tyres of this crane just exploted, you would have felt exactly what you felt.
When a high pressure truck tyre explodes, and the tyres on this kind of crane a really high pressure ones, you better are not close!
https://www.youtube.com/watch?v=294Wu6O0uW0That's my bet! And despite the crane driver would have felt the tyre explosion, he wouldn't have stopped but many miles away, and you wouldn't see him stopping on the other side. So, you couldn't have a clue it was one of his tyres that blasted.