Complex sentence: Extension of rail link to Digha from Tamluk was sanctioned in 1984 and it took 20 years to complete this project in two phases, the first phase of linking Tamluk and Contai completed in November 2003 and the tourist destination Digha got connected to Howrah in December 2004.
Split into simpler sentences: Extension of rail link to Digha from Tamluk was sanctioned in 1984; it took 20 years to complete, in two phases. The first phase linked Tamluk and Contai in November 2003, and the tourist destination Digha was connected to Howrah in December 2004.