The State Opposition has promised to build a railway line to Ellenbrook by the end of 2018 if it wins the March election.
The Labor leader Mark McGowan says the 21 kilometre line would cost $863 million, excluding the cost of new rail cars.
It would connect to the Midland line and stop at Morley, Noranda, Bennett Springs and Whiteman.
Both major parties committed to an Ellenbrook line at the last election and Labor has constantly attacked the Premier Colin Barnett for dumping the plan.
The Premier has previously argued there is not enough demand for the line but Mr McGowan insists population growth means it is badly needed.
He says the Government should never have scrapped it.
"Today, I'm here to right a wrong, the wrong that was committed to the people of Ellenbrook by Colin Barnett," he said.
The Ellenbrook line would be part of Labor's heavy rail proposal, known as Metronet.
Yesterday, Mr McGowan also promised to build a railway line to the Perth Airport by mid-2018.
The 10.5 kilometre rail line, stopping at Redcliffe, the airport and Forrestfield, would cost $731 million, but that does not include the cost of new rail cars to service the line.
Mr McGowan says the airport line is a priority for Labor.
Labor has costed Metronet at $3.8 billion but the Treasurer, Troy Buswell, has previously estimated it at $6.4 billion.