Chennai: Perambur railway police on Wednesday arrested a 24-year-old man who used a stick to knock mobile phones from the hands of passengers travelling on the footboards of Chennai suburban trains.Police identified him as Hari Babu of Old Washermanpet. His modus operandi was to stand beside the railway tracks, use a stick to knock the phones down before fleeing with them. Passengers travelling near open doors and windows were particularly vulnerable.Police said he used the method repeatedly between Basin Bridge and Vyasarpadi railway stations. Following several complaints, officers maintained surveillance and arrested him. Hari Babu is involved in more than 25 cases, including property offences.