The 19km line will branch off the existing Max line between PSU South and Lincoln Street stations, running southwest along Barbur Boulevard, entering Tigard along 70th Avenue and Elmhurst Street. The alignment then crosses Highway 217 and follows the existing commuter rail line south to a terminus at Bridgeport Village shopping mall.

The line will serve 13 stations, seven of them with park-and-ride facilities.

Transport authority TriMet will now begin advanced design work and develop detailed cost estimates for the project, which has an anticipated pricetag of between $US 2.64 and 2.86bn at 2024 prices.

According to the current timeline, a record of decision is expected on the final Environmental Impact Statement for the project at the end of next year. A vote on regional funding is scheduled for the end of 2020 and if this is approved, an application for federal funding will be made in 2022.

Construction is expected to begin in late-2022, with the line opening towards the end of 2027.