Under Section 22 of the Public Order Ordinance (Cap. 245), any person taking part in a riot who unlawfully and with force prevents, hinders or obstructs, or attempts to prevent, hinder or obstruct, the loading or unloading, or the movement, of any motor vehicle, tramcar, aircraft, train or vessel, or unlawfully and with force boards, or attempts to board, any motor vehicle, tramcar, aircraft, train or vessel with intent to do so, shall be guilty of an offence and shall be liable on conviction to a fine and to imprisonment for 3 years.