Rotterdamse Elektrische Tram (RET; ) is the main public transport operator in Rotterdam, Netherlands. It started in 1905 when they took over the city tram lines from RTM (Rotterdamsche Tramweg Maatschappij). It currently operates 64 bus lines, 11 tram lines and five metro/light rail lines in Rotterdam and the surrounding municipalities. RET used to employ the National Tariff System, like other local transport companies in the Netherlands. On 29 January 2009, metro trips switched to using an OV-chipkaart; bus and tram trips followed on 11 February 2010. Tram Tramlines Bus Buslines Metro Metrolines External links Official website Tram transport in the Netherlands Public transport operators Light rail in the Netherlands Transport in Rotterdam Transport in South Holland Dutch brands