A merge in turn, or 'zip merge,' is a system where drivers use both lanes until a closure point, then alternate merging. However, the rise in drivers blocking the empty lane and preventing cars from 'pushing in' is frustrating other motorists, and it can lead to a fine. Merging in turn takes place before an upcoming lane closure (Image: Getty Images)What does the Highway Code say about the merge in turn? A video was recently shared on Reddit of a van blocking an upcoming empty lane due to an impending lane closure, and drivers shared their anger at the situation. Is it illegal to block a merge lane in the UK?