The project will install a fourth lane between Hyland Avenue and Bonneyview Road, to make it a permanent two-way dual carriageway.
Flagstaff Road is a major arterial road used by approximately 21,000 motorists every day to commute to other parts of the city.
For 800 metres of its overall 3.3 kilometre length the road consists of only three lanes.
Flow on the centre lane is reversed daily to cope with peak-hour traffic in the mornings and evenings.
This is a potential cause of confusion for motorists travelling during these periods and remains a safety concern. The extra lane will provide room for vehicles to safely overtake slow-moving traffic and allow emergency vehicles to proceed without being held up by other traffic.
This project is expected to support approximately 40 full time equivalent jobs per year, averaged over the life of the project.