Simplify the following text for a Grade 11 native English-speaking person.
Original: The Chelseaâ `` Hackney line ( also referred to as the Chelney line , Kings line and Crossrail 2 ) is a safeguarded route for an underground railway running from south-west London ( UK ) to north-east London .
Simplified: The Chelsea-Hackney ( or `` Chelney '' ) line is a safeguarded route for an underground railway running from south-west London to north-east London .