Mr Bridges said the project would benefit not only Tauranga and Western Bay of Plenty residents, but people from Rotorua and the Eastern Bay of Plenty too.
It was the final piece in what as known as the Bay of Plenty's "eastern corridor", connecting the $445 million Tauranga Eastern Link to the Port of Tauranga, he said.
"It's a $120 million investment in this city and this region."
The project timetable was looking good, Mr Bridges said.
"We know we can do this in three years and open this project in 2020."
Mr Brownless noted there would be some temporary "pain" for residents while the work was undertaken.
"Once we have been through the pain, and these things do take a while to complete, it is going to make things so much better."
The project began at the end of 2015. The first stage of work - earthworks and relocating the East Coast Main Trunk railway line - was completed in December.
From this month, CPB Contractors will start establishing site offices and relocating existing services, ahead of major earthworks later in the year, according to the transport agency.
Final designs for the flyovers have yet to be completed.
The initial design for the Bayfair flyover attracted controversy as it removed a popular pedestrian and cyclist tunnel underpass roundabout.
That decision was being revisited, Mr Bridges said, and the options were being worked through now.
"The community can be confident that there will be good walking and cycling amenities."
Mr Bridges said the Government had a strong track record of providing good options for pedestrians and cyclists, as well as beautification, in new roading projects in Tauranga. He cited the Tauranga Eastern Link as an example.
The ceremonial project launch was held on land between Eversham Rd and SH2 near Baypark.
Invitees included representatives of local iwi and hapu - Nga Potiki, Ngati Tapu and Ngai Tukairangi - contractors, transport agency staff, Tauranga district councillors, residents and Te Kura o Matapihi students.
Baypark to Bayfair project timeline
Start date: December 2015
First phase completed: December 2016
Second phase started: May 2017
Completion date: December 2020