 Melbourne's record population growth of more than 125,000 people a year made both party leaders focus on big transport initiatives.Labor unveiled a $50 billion underground rail loop of the suburbs surrounding the city, though admitted the project would not be completed before 2050 and actually pledged $300 million for a business study.The Coalition instead proposed a $19 billion "European-style" regional rail network that would rebuild the entire network and include high-speed rail on four lines, travelling up to 200 km an hour.