The Transport Agency is standing by its decision to close part of State Highway 1 in Auckland this weekend, saying it hopes disruption will be kept to a manageable level.
The south-bound lanes of the southern motorway, between Gillies Avenue and Greenlane, are being closed for up to 36 hours from Saturday night.
The closure will enable the agency to switch south-bound traffic onto the new Newmarket viaduct.
However, some retailers fear it will have a huge impact on Father's Day business.
The Transport Agency says if motorists heed its advice to keep clear of the area, traffic hopefully will be kept within manageable levels.
About 40,000 vehicles usually use the section being closed and the agency says if normal traffic levels are maintained severe congestion will build up quickly throughout the region.