As Phoenix drivers head for Flagstaff during the summer, traffic frequently grinds to a standstill on Interstate 17.
The Arizona Department of Transportation hopes to end those backups.
ADOT has begun negotiations with a design company that will oversee improvements on 23 miles of the freeway between Anthem Way and Sunset Point.
That section can see more than 50,000 drivers a day and is where many of the backups take place.
The project will widen the road and a number of bridges.
It will also install an eight-mile flex lane system to reduce congestion during peak travel times.
The work is expected to take about three to three and a half years.
