The invention concerns a method for coding congestion affecting several traffic lanes, in the context of digitally coded traffic information containing, in the form of elements, a site located on a traffic lane, and the size and direction of the congestion. Said data are decoded by a look-up table of sites. The method is characterised in that when a congestion is announced extending by its size beyond a branch road onto another traffic lane, another element is used for coding the following data: branch roads affected by the congestion, direction and size of the congestion.