Since the original environmental statement was published (Ministerial Statement 84), a detailed review of the whole route between middle Swan and the Metropolitan Region Scheme boundary at Wooroloo has been completed. As a result of these studies, Main Roads consider that some sections of the original route need to be changed. In its letter to the Minister for the Environment, Main Roads also indicated that a detailed study of the possible alignment options for the Perth to Adelaide National Highway from the Metropolitan Region Scheme boundary and Clackline will be undertaken.
The section of the highway outside the metropolitan Region Scheme to Clackline will need to be assessed separately and is not included in this report.
The changes requested as a part of this section 46 amendment specifically relate to variations in alignment in the following sections of the approved Perth to Adelaide National Highway route:
- Gidgegannup to the Metropolitan Region Scheme boundary near Wooroloo;
- Around Gidgegannup townsite;
- Top of Darling Scarp to Gidgegannup;
- Campersic Road to top of Darling Scarp.
A section of John Forrest National Park (System Six Recommendation Area M21) is affected; and Roe Highway to Campersic Road. Crossing of Jane Brook (System Six Recommendation Area M20) at Toodyay Road is required. This section of the highway route has not previously been referred to the Environmental Protection Authority. Although not part of the original assessment, it forms a logical extension westward to the route assessed and is considered in this report.