The railroad spur on the Maricopa-Casa Grande Highway near the Frito-Lay plant in Casa Grande will hold up traffic as the track is replaced and the road resurfaced.
The work began last week and will last for an unknown period of time.
Pinal County is working with Casa Grande to maintain traffic flow while the area is under construction, according to county officials.
The rail improvement will be completed first. The new pavement will be put down after that for about 1 1/2 miles from the crossing to Ethington Road.
To check road conditions, call the county's information line at (520) 866-6078.