Simplify the following text for a Grade 9 native English-speaking person.
Original: The Brisbane Riverwalk , a floating walkway over the Brisbane River linking the inner city neighborhoods of Fortitude Valley and New Farm , broke up , with a section forming a 300 m `` floating missile '' that threatened the Sir Leo Hielscher Bridges .
Simplified: The Brisbane Riverwalkâ '' a floating walkway over the Brisbane River linking the inner city neighborhoods of Fortitude Valley and New Farm broke up . One section formed a 300 m `` floating missile '' that threatened the Sir Leo Hielscher Bridges .