The Liberals have promised to build the 37km bypass road known as the Perth to Darwin Highway if they win the March 9 election - but work will not begin until 2016 and the pledge relies on the Federal Government stumping up most of the $830 million cost.
Premier Colin Barnett and Transport Minister Troy Buswell yesterday promised $196 million for the project, which aims to take 3000 heavy vehicles a day off Great Northern Highway, which runs through the Swan Valley wine-growing and tourist region.
The bypass road, which would run from Great Northern Highway between Brand Highway at Muchea and the intersection of Reid and Tonkin highways in Beechboro, would run through two key marginal seats.
Swan Hills is held by the Liberals' Frank Alban and West Swan is held by Labor's Rita Saffioti. Each party has genuine hopes of winning both seats.
In January, Mr Alban wrote to electors promising a re-elected Liberal government would start building the road next year. But the Liberals' promise yesterday was to begin construction by 2016 with the project to be finished by 2019.
Mr Buswell said the Great Northern Highway through the Swan Valley was the "artery" through which much of the wealth of the resources industries in WA's north flowed and the project would open up new industrial land north of Ellenbrook.
He said he expected the Commonwealth would be required to fund "at least 50 per cent".
"These are the sorts of road projects the Commonwealth will contribute to," Mr Buswell said.
A spokesman for Federal Infrastructure Minister Anthony Albanese said the project would be "considered on its merits against other priorities in WA".
Labor leader Mark McGowan said announcing an $830 million project with only $196 million of funding "smacks of desperation".
"This is a half-baked announcement and Mr Barnett must also reveal if this funding will simply be added to the Barnett Government's spiralling State debt bill," he said.
Swan Valley Progress Association vice-president Peter Enright welcomed the announcement.
He said the mixture of heavy trucks and farm machinery from the wineries was a traffic hazard.