M4 / A4 is the main route between the Blue Mountains, Sydney's western suburbs and Sydney's CBD. Except within the inner western suburbs of Sydney, the route parallels one of Australia's earliest road routes, Parramatta Road / Great Western Highway.
Road conditions vary from freeway standard, tunnels, through to suburban arterial. With a minimum of 3 lanes in each direction.
Planning began for the Western Expressway in 1947, as the County of Cumberland Planning Scheme (CCPS) was being drawn up, which included a corridor from the City of Sydney at Glebe to the Gt Western Hwy at Lapstone, passing through Glebe, Haberfield, and Five Dock before joining the current route at Concord. This corridor was reserved in 1951. 2
The first section of the M4 Motorway was from Prospect to Penrith, completed by the NSW Government in the early 1970's. Various stages of the second section from Concord to Parramatta were completed during the 80's, with a missing link of approximately 10 km between Mays Hill, near Parramatta, and Prospect to connect these two sections. 2
In 1989 the NSW Government invited proposals from private enterprise to fund and construct the missing section of roadway, and upgrading a further 11 km of the F4 Freeway. Statewide Roads Limited (SWR) won the right over a 20 year period to finance and build, and then operate and maintain the Motorway, after which the Motorway reverted back to Government control at no cost. 3
The opening of the M4 Western Motorway in May 1992 included 21 major bridge structures, and the upgrade and widening of 11 kilometres of existing expressway at a cost of $245 million. The completion of this section provided uninterrupted motorway conditions between Concord and Lapstone on the foothills of the Blue Mountains. Between 1996 to 1998 an upgrade and widening of the M4 Western Motorway to 3 lanes each way from Parramatta to Penrith was completed. 3