MOTORISTS have a three-year wait until they can start driving on the $215 million Mitchell Freeway extension to Alkimos.

The State Government is seeking expressions of interest from industry to design and build the 5.6km extension from Hester Avenue to Romeo Road and associated connections.

Construction is expected to start in late 2020 and take about two years to complete, creating 1200 jobs.

The project will include finishing the Hester Avenue interchange, building another interchange at Lukin Drive and building Romeo Road between Marmion Avenue and Wanneroo Road.

It will also include building a rail tunnel for the train line at Butler station, widening Wanneroo Road from Romeo Road to Trian Road, a shared path for cyclists and pedestrians, noise walls, street lights and safety barriers.

It is being built to meet the needs of the growing population in Yanchep, Alkimos and Eglinton, which has increased from about 3000 people in 2006 to about 30,000 and is expected to reach about 118,000 people by 2031, according to the State Government.

Construction is expected to take two years, starting late 2020, subject to all environmental and heritage approvals.