Costing $4.8 million the construction is set to take several months with completion due, weather permitting, in September.

The work includes the realignment of Hill Street, which is underway, and the re-positioning of the bluestone gates at the entrance to the Botanic Gardens car park to widen the narrow entrance.

Orange City Council infrastructure committee chair Cr Jeff Whitton said the NDR traffic would not be affected until April as the current work is occurring to the south of the NDR.

"During the later stage we'll be trying to keep as much of the bypass open as we can," he said.

"There should always be at least one lane open in either direction.

"Because we're re-aligning the top of Hill Street, we're also taking up the opportunity to re-position the bluestone gates at the entrance to the Botanic Gardens car park.

"Throughout the process, access to the restaurant, the Adventure Playground, the Botanic Gardens and Emmaville Cottage won't be affected."

Orange mayor Reg Kidd said when finished the roundabout would benefit the area.

"This roundabout is going to make a huge difference to traffic flow in the area, so the sooner it's built the better," he said.

The project is being funded by $2.35 million from the state government Resources for Regions program with the rest coming from council and industry contributions.