Motorists travelling between the West Coast and Canterbury will be faced with delays for the next 10 weeks.
From today, until early July, Waka Kotahi NZ Transport Agency will be repairing a retaining wall at Porters Pass, west of Springfield on State Highway 73.
The retaining wall has been in urgent need of repair, but Covid-19 supply chain delays have meant the work has only been able to be carried out now.
Traffic signals combined with a 30km/h speed restriction will allow single-lane traffic to pass the site safely over a 1.2 km stretch for the duration of the work, Waka Kotahi NZTA journey manager Tresca Forrester said.
Crews will be working daytime hours and motorists will be affected 24/7, she said.