i think by waking up before the lorry hits,this in itself is a symbolic reference,may refer to your own thoughts of refusing to face something head on,or that the thought of a particular solution seems distasteful,
what would have happened if you didn't wake up from the dream ?
i am reminded of the juggernaut from Hindu mythology also another name for a lorry ,this god was a great obstacle remover,i think of a storm or tornado passing through ,can be destructive ,but clears the way for new growth,i think you already know this as your second comments refer ,
in myth the would be hero enters the cave to confront the dragon,this may be that moment for you,be brave sir knight,it is always darkest before the dawn.
hope my thoughts are of help,
rgds mikey