Image Source: CC licence by https://www.flickr.com/photos/amy_elizabeth_west/3876549126 CROWD MANAGEMENT Large events require organizers to manage crowds.Therefore, LEAs use social media to manage crowds. Twitter is most often the medium of choice to manage crowds. http://socialmediadna.nl/social-media-for-social-order-crowd-control-bij-evenementen/ For many years, the Rotterdam police is using social media during the Rotterdam Summer Carnival. http://socialmediadna.nl/zomer-carnaval-en-crowd-control/ Another Dutch event is Glazen Huis, where LEAs have been using social media for crowd control. http://socialmediadna.nl/glazen-huis-en-crowd-control/ Also city officials in Amsterdam use social media for crowd management. http://socialmediadna.nl/troonswisseling-veilig-door-feest/ Dutch TNO organisation reports on using social media to direct people. http://socialmediadna.nl/crowd-in-control/ There also also apps that measure crowd density based on social media and app usage. http://socialmediadna.nl/app-druktemeter/ There are apps supporting the kettling tactic. http://socialmediadna.nl/sukey/ The Police Service of Northern Ireland issue regular information, traffic advice and get home safe advice in relation to large events across their social media platforms. PSNI also issue relevant traffic advice while events are ongoing.