Europe\'s busiest port of Rotterdam opened a multi-billion euro extension on Wednesday, with wider and deeper basins to accomodate the world\'s biggest freight ships. The Maasvlakte 2 project is the largest feat of Dutch maritime engineering in decades and is forecast to only reach full completion in 20 years. The initial stage of the extension has been completed at a cost of 1.55 billion euros ($2 billion), 150 million euros less than planned, project director Rene van der Plas told journalists. The overall project will cost around 3 billion euros and is seen as the crown jewel at the entrance of the iconic Port of Rotterdam, the world\'s fourth-biggest harbour. \"This means more space for big new sea containers, space for new beautiful terminals and 2,000 hectares for Rotterdam,\" said Infrastructure and Environment Minister Melanie Shultz van Haegen. \"It also means thousands of direct and indirect jobs. I\'m unbelievably proud of this,\" she said as she officially opened the port extension. Engineers have now completed the bare bones of a vast harbour network by moving 240 million cubic metres of sand, enough to fill Rotterdam\'s De Kuip football stadium 160 times, the port said in a statement. While the port is now accessible to sea traffic as well as trains and inland water traffic, the first container ships are only expected to unload at two new container terminals in late 2014, Van der Plas said. The development includes a 3.5-kilometre (two-mile) hard seawall built with seven million tonnes of stone and 20,000 concrete blocks to resist the North Sea\'s relentless onslaught. By 2033, when its four deep-water basins become fully operational the new addition will nearly double the port\'s current capacity of handling 19 million containers per year to 36 million. It will allow super-sized container ships larger than aircraft carriers to dock around the clock and push Rotterdam\'s sea traffic from a current 34,000 to an estimated 57,000 ships per year by 2035. Over the last decade container ship capacity has nearly doubled to 18,000 containers, while their size has swollen to some 400 metres long and 60 metres wide. Despite the global economic crisis, container traffic is expected to double by 2030, even according to the most pessimistic forecasts.