The final stage of Tauranga's Baypark to Bayfair upgrade will get underway next month.
The road works project will include building two flyovers.
One flyover would take State Highway 29a traffic over the railway line and the Te Maunga intersection, and the other would take State Highway 2 traffic up and over the Maunganui-Girven roundabout.
CPB Contractors was awarded the contract.
Transport Agency Bay of Plenty highways manager Niclas Johansson said the contractors would be onsite from mid-May and people would notice changes over the coming months.
The final design was being developed and site offices and relocation of existing services would begin relatively soon, he said.
The Baypark to Bayfair link was designed to reduce congestion and improve safety by separating local and state highway traffic.
It would also support economic growth in the region by improving the route to the Port of Tauranga.
Mr Johansson said stage one went well after being started in December 2015.
Stage one involved enabling works, major earthworks and the relocation of the East Coast Main Trunk Line railway and was completed in December 2016.
"All going to plan we expect to have traffic using the new flyovers by 2020. Once it is finished it will make a real difference to commuters."
As part of the roadworks, the existing Maunganui-Girven intersection would also be upgraded, the Te Maunga roundabout replaced with an elevated interchange and walking and cycling connections would be improved between Baypark and Bayfair.
The proposed walking and cycling routes were being reviewed during the final design phase.
The $120 project would connect to the Tauranga Eastern Link, completing the Eastern Corridor.