Drivers accessing the Cromwell town centre centre from State Highway 6 will have to take a detour until the end of May.
The short detour along Shortcut Rd is in place while two new roundabouts are constructed.
Waka Kotahi NZ Transport Agency is constructing a 20m-radius single-lane roundabout to replace the existing T-intersection linking State Highways 6 and 8B Queenstown and Wanaka rising crash numbers caused the organisation to consider safety improvement options.
On State Highway 8B a roundabout , including a pedestrian underpass, is being constructed at the Wooing Tree Estate intersection.
The work is being funded by the Wooing Tree developers after a bid to have Central Otago District Council contribute $630,000 towards the project was rejected in December.
Transport agency system manager Lower South Island Graeme Hall said there would be a lot of construction activity and people would need to slow down, pay attention to the road and follow the temporary traffic management in place.
Since Tuesday, Queenstown and Wanaka drivers travelling into Cromwell or towards Alexandra, Dunedin or Christchurch are having to detour via Shortcut Rd.
There will be no change for drivers from Cromwell heading to Queenstown or Wanaka along State Highway 8B, or for drivers heading along State Highway 6 but not travelling into Cromwell.