Motorists have been advised to leave 15 minutes earlier while the busiest stretch of the West Tamar Highway is upgraded.
A $1.16 million overhaul of the Forest Road south intersection - which links the highway to Trevallyn - will begin in early September, requiring detours and reduced speed limits.
By late October, the new-look intersection will be fitted out with new traffic lights, pedestrian lights, and a left-turn lane.
There will also be improvements to traffic islands, a pedestrian refuge and better bike and shared pathway connections.
The state government anticipates the changes will add an extra five to seven seconds to highway trips during peak times, but reduce delays and improve safety.
Infrastructure Minister Kerry Vincent said the two-month project followed the recently completed $36 million highway duplication project at Legana.
"As with the Legana project, these improvements to the Forest Road intersection will give the community a safer, more efficient section of road," Mr Vincent said.
"[This] means less time sitting in traffic for road users, and more infrastructure to support pedestrians, cyclists, and those catching public transport."
Contractor Hazell Bros has begun setting up a worksite in the nearby silt ponds car park, which was constructed for the TERHAP project in 2023.
Early construction works will be completed between August 24 and early September, and be followed by two months of "higher impact work".
Detours in place from September will require citybound traffic exiting Forest Road south to instead turn left, travel 500 metres and perform a U-turn outside 89 West Tamar Highway, opposite the old 'Mud Flat Autos' strip.
Highway traffic that would usually turn right onto Forest Road south will instead be required to travel an extra 400 metres towards the city before making a U-turn at Tamar Yacht Club.
These detours will only be in place during working hours.
A 2020 RACT report found that the city end of the West Tamar Highway typically recorded 29,000 vehicle movements each day.
