Simplify the following text for a Grade 7 native English-speaking person.
Original: Construction began on 24 April 1999 and the line officially opened in 2002 , taking over the train tracks running through the Eastern Harbour Tunnel from the Kwun Tong Line , running from Po Lam to North Point .
Simplified: Construction began on 24 April 1999 and the line officially opened in 2002 . It took over the train tracks running through the Eastern Harbour Tunnel from the Kwun Tong Line , and ran from Po Lam to North Point .