\r\n\r\nThe work involved renewing 186km of rails, 21 points, about 130,000 sleepers and 110,000 tonnes of ballast. Single-line working with temporary speed restrictions were instigated which extended the Berlin - Hannover journey time by about 25 minutes.\r\n The 250km\/h Berlin - Hannover line is one of the busiest main lines in Germany with about 170 trains\/day, and DB says it is one of the few high-speed lines in Germany to be used by ICEs, conventional Intercity and freight trains. "That is the reason for faster rail and sleeper wear," Mr Holger Bajohra, infrastructure spokesperson for DB, told IRJ. "Additionally, two years ago it turned out that some of the sleepers are made from poor quality concrete."\r\n DB Networks adopted a process called integrated bundling in 2007 which combines work on track, signalling, catenary, and stations into one period. This means the timetable only has to be altered once, rather than for several short periods. This also makes more productive use of workers and machinery, particularly the large track renewal machines.