Simplify the following text for a Grade 10 native English-speaking person.
Original: In 1972 , the Hong Kong government authorised construction of the Initial System , a 20-km system that roughly translates to the Kwun Tong Line today ( except the line now extends to Tiu Keng Leng ) .
Simplified: In 1972 , the Hong Kong government authorised construction of the Initial System , a 20 k system that roughly translates to the Kwun Tong Line of today .