Work on the Shirley Rd, Hills Rd and Warrington St intersection safety upgrade got under way on Monday.
Christchurch City Council says the intersection was one of the most crash-prone in Christchurch - and in need of an upgrade.
But it is taking a toll on morning commuters who had to wait for up to 30min travelling west on Shirley Rd.
Commuters heading south towards the city centre on Hills Rd were forced to wait even longer at the intersection on Monday.
The city council expects the work to take more than a month to complete, with motorists warned to expect ongoing delays.
Contractors are installing a permanent raised safety platform across the intersection to lower the speed of vehicles to 30km/h.
Other changes include a raised pedestrian crossing, new turn signals and other traffic calming measures.
It will be the third large-scale raised safety platform to be installed on the city's roads. Similar measures were put in at the Lincoln Rd/Barrington St/Whiteleigh Ave intersection in 2022 and the Marshland Rd/Briggs Rd/Lake Terrace Rd junction last year.
Work is also due to start next month on another safety platform at the Shirley Rd/Marshland Rd/New Brighton Rd/North Parade intersection next to The Palms shopping centre.
- By Geoff Sloan, made with the support of NZ On Air
