Construction crews are again working on Highway 7 between Stonewall and the Perimeter Highway, after it was repaved last year.
Cracks appeared in the road over the winter.
The province said it doesn't know why, so it will conduct tests.
Only the southbound lanes of the highway are affected. One lane is still open.
University of Manitoba engineering professor Trisha Stadnyk said the cracks could be the result of any number of factors, including the concrete mix, and design and installation, to the harsh winter Manitoba had.
"Things like this happen," she said. "We live in an environment where it's incredibly difficult to find the right technologies to be able to support the kind of weather changes and shifts that we have, so things do go wrong."
The province says the fixes will be part of normal warranty work.