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.

"On weekends, manual traffic management [stop/go] may be used at peak times, for example, to ensure people can get to skifields in the mornings and away in the afternoons without undue delay."

Some ski operators fear the upcoming season could be impacted by the roadworks.

Porters Alpine Resort general manager Blair James said there could be a bottleneck of traffic, similar to when the road was impacted by a large fire in 2019.

Forrester said they have talked to the skifield operators on SH73.

"And are in close communication with them if they open in June or early July. In the event of snow falling on the highway, crews will disestablish for the day and if possible, open the route to two lanes."