The 9th Circuit Court of Appeals voted against repealing plans to expand the Loop 202 through the South Mountain Preserve.
On Friday, the judges decided unanimously to let the Arizona Department of Transportation move forward with construction on the 22 mile stretch of freeway.
Proponents claim it will relieve Interstate 10 traffic congestion by linking the East and West Valley for an alternate route.
The Gila River Indian Community and environmentalists filed the appeal arguing planners violated both the Environmental Protection Act and the Department of Transportation Act.
