The business case is to extend the Armadale Line approximately eight kilometres south to Byford. This is to support and provide public transport access to the high-growth suburb of Byford.

The business case was accepted for Infrastructure Australia's evaluation on 14 July 2020.

The Byford Rail Extension proposal has not been added to the Infrastructure Priority List as a project. The Perth south-east corridor capacity improvements will remain as a Priority Initiative on the Priority List and we would welcome the opportunity to review a revised business case.

This evaluation was completed before the raising of the threshold for an Infrastructure Australia assessment from $100 million to $250 million of Commonwealth funding being sought.