"It is a great day for the BVG," said Dr Sigrid Nikutta, chair of the management board of Berlin Transport Authority (BVG). "The U5 gap closure project is on budget and on time."\r\nWork on the 10-year \u20ac525m project began in April 2010 and is now at the halfway point. According to Mr Stefan Roth from the construction company Implenia, the second tunnel was bored at an average of 11m per day, rising to 28m per day under the best conditions, and without any accidents.\r\nThe next phase involves the construction of three intermediate stations at Berliner Rathaus, Museumsinsel and Unter den Linden, where Line U5 will interchange with Line U6. Museumsinsel presents the greatest challenge as it will be constructed beneath a canal with an entrance on each bank.\r\nWhen the new section opens in 2020, Berlin's main station, which is currently only served by the U55 shuttle, will be much better connected to the U-Bahn network.