By the 1970s Melbourne was the only Australian city with a major tram network. Melbourne resisted the trend to shut down the network for three major reasons: partly because the city's wide streets and geometric street pattern made trams more practicable than in many other cities; partly because of resistance from the unions; and partly because the Chairman of the MMTB, Sir Robert Risson, successfully argued that the cost of ripping up the concrete-embedded tram tracks would be prohibitive. Also, the infrastructure and vehicles were relatively new, having replaced Cable Tram equipment in only the 1920s–1940s. This destroyed the argument used by many other cities, which was that renewal of the tram system would cost more than replacing it with buses. There is a 1960s colour film called "Citizen Tram" on YouTube commissioned by Risson too.