The MTA is also testing smaller ideas on some services. Starting in late 2015, 100 "station platform controllers" were deployed for the F, 6, and 7 trains, to manage the flow of passengers on and off crowded trains during morning rush hours. There were a total of 129 such employees, who also answer passengers' questions about subway directions, rather than having conductors answer them and thus delaying the trains. In early 2017, the test was expanded to the afternoon peak period with an increase of 35 platform conductors. In November of the same year, 140 platform controllers and 90 conductors gained iPhone 6S devices so they could receive notifications of, and tell riders about, subway disruptions. Subway guards, the predecessors to the platform controllers, were first used during the Great Depression and World War II.