Newell Highway traffic has now been switched onto the new Parkes Bypass.

The new section of the highway opened on Tuesday.

It's been six years in the making since the project was first conceived, added to Infrastructure Australia's Priority List a year later and almost four years of construction after the contract was awarded to Georgiou Group.

While some areas still require work, drivers will get their first feel of the new road that's been relocated two kilometres west of the centre of Parkes where it previously passed through.

It's to improve freight efficiency and productivity, and the safety of drivers and pedestrians, particularly across Bogan Street in Parkes, by removing 1200 trucks per day from local streets.

For drivers coming from Forbes there will be some temporary changes if you're travelling into Parkes.

Some traffic conditions will remain in place for up to three months as crews complete further work on the project including landscaping and completion of the north and south connections to the existing highway.

Transport for NSW says the main access between Parkes and the bypass will be the Condobolin Road roundabout, which opened to traffic in all four directions on Tuesday.

Access to and from the bypass will also be possible from London Road, however this access will be under temporary traffic controls

There will be restrictions to some sections of the existing Newell Highway north and south of Parkes.

In the north, the existing Newell Highway will be closed between the rest area and Maguire Road.

Southbound vehicles will be able to access Parkes via Bogan Road while northbound vehicles will use the bypass from the Condobolin Road roundabout.

And in the south, the existing Newell Highway will be closed between Saleyards Road and Barkers Road.

Heavy vehicles wishing to travel east will be required to travel on the Hartigan Avenue extension (state road network MR61).

"For the safety of workers and motorists, some single lane closures, reduced speed limits and intermittent stopping will be in place during this work," said Transport for NSW.

Beginning at Barkers Road in the south and reconnecting at Maguire Road in the north, it's 10.5 kilometres long with five key intersections: Two T-intersections north and south between the existing Newell Highway and the bypass, split T-intersection at London Road, four-way roundabout at Condobolin Road, T-intersection with Bogan Road, and two bridges over rail lines and Hartigan Avenue, and over the bypass on Victoria Street.

It also bypasses tight bends in the town and two railway level crossings at Hartigan Avenue near Parkes KFC and the Welcome crossing in the south.

There's also been an extension of Hartigan Avenue to Henry Parkes Way/Condobolin Road which opened to traffic under its bridge on 21 November, as did the bypass roundabout.

The new BP Highway Service Centre along the bypass on the left near the roundabout is also well under construction.

Other work over the last four years has seen part of Moulden Street shifted to the west, Maguire Road and Nock Road converted to cul-de-sacs, a new connection between Brolgan Road and Hartigan Avenue, and a new shared path for pedestrians and cyclists which will connect Brolgan Road, Condobolin Road and Victoria Street.

Motorists are advised to drive to the conditions and to follow the directions of signs and traffic control.