Preparation works on the Southern Ports Highway between the Southend and Robe turn-offs have recommenced following the winter break.
Council’s Director of Engineering Services, Peter Halton, said weather conditions will play a critical role in completing the project.
Mr Halton said the project is progressing well, with more than 10 kilometres of the upgrade already completed from the Beachport Outlet.
"This project is delivering a safer, stronger and more reliable road for our region, and we are now preparing to complete the final stage," he said.
From September, the detour will be in place via Hatherleigh, and the highway will be closed once again to the public between 7am and 5pm, Monday to Friday, while construction crews are on site.
Outside these hours, including weekends and public holidays, the road will remain open, speed restrictions and occasional delays will apply. Updated signage will be in place to guide motorists.
Council reminds road users to follow all traffic management measures and observe speed restrictions through the work zone.
"The cooperation of motorists is essential to maintaining a safe environment for workers and the community, while helping us deliver the best possible outcome for this significant project," Mr Halton said.
Weather permitting, the Southern Ports Highway upgrade is expected to be completed before Christmas.
Local residents and businesses who regularly travel between Southend and Beachport may be eligible for a permit allowing restricted access during construction.
For permit information and project updates, visit Council's website.