The westbound lane over the hill, heading from Chalong to Kata, will be closed from 8am to 5pm today, the Phuket Info Center announced in a notice posted online last night.
The section of lane to be closed is from km.1+575 to km.2+300 around the Khuan Sato curve, westbound heading from Chalong to Karon.
Motorists driving from Karon to Chalong will not be affected.
However, motorists needing to travel over the hill from Chalong to Kata and Karon are advised to drive south along Wiset Rd, then turn right onto Saiyuan Rd in Rawai, then drive along the road across the southern end of the island (Route 4020) and follow it northwards all the way up to Kata and Karon.
Large vehicles such as trucks and buses were advised to not use the detour as some of the hills along the route are steep, the notice said.
Traffic Police will be stationed along the route to help direct motorists, the notice added.
The Phuket Highways Office has previously apologised for any inconvenience caused by the lane closure, which is required for work to be conducted on making major repairs to the road.
The busy road remains damaged after heavy rain washed away support for pylons holding up the road in October 2020.
The Phuket Highways Office has maintained that the road is safe to use, despite the westbound section of the road being reduced to one lane.
The move to make progress on repairs to the road finally resumed this year after National Ombudsman Assoc Prof Issari Hunsajaroonroj inspected the road in person in November last year.
Following that visit, local government offices were asked in January to coordinate efforts to acquire land that will allow for a new road to be built for vehicles descending Kata Hill to make crossing the hill from Kata to Chalong safer.