  Although it is widely recognised that the presence of groups influences
microscopic and aggregated pedestrian dynamics, a precise characterisation of
the phenomenon still calls for evidences and insights. The present paper
describes micro and macro level original analyses on data characterising
pedestrian behaviour in presence of counter-flows and grouping, in particular
dyads, acquired through controlled experiments. Results suggest that the
presence of dyads and their tendency to walk in a line-abreast formation
influences the formation of lanes and, in turn, aggregated observables, such as
overall specific flow.
